Merge branch 'refs/heads/dev' into feat/folia

# Conflicts:
#	core/src/main/java/com/volmit/iris/core/nms/INMSBinding.java
#	core/src/main/java/com/volmit/iris/core/tools/IrisCreator.java
#	core/src/main/java/com/volmit/iris/engine/framework/Engine.java

core/build.gradle.kts

@@ -87,6 +87,7 @@ dependencies {
     slim(libs.commons.io)
     slim(libs.commons.lang)
     slim(libs.commons.lang3)
+    slim(libs.commons.math3)
     slim(libs.oshi)
     slim(libs.lz4)
     slim(libs.fastutil)
@@ -165,15 +166,6 @@ tasks {
             "version" to rootProject.version,
             "apiVersion" to apiVersion,
             "main" to main,
-            "environment" to if (project.hasProperty("release")) "production" else "development",
-            "commit" to provider {
-                val res = runCatching { project.extensions.getByType<Grgit>().head().id }
-                res.getOrDefault("")
-                    .takeIf { it.length == 40 } ?: {
-                    logger.error("Git commit hash not found", res.exceptionOrNull())
-                    "unknown"
-                }()
-            },
         )
         filesMatching("**/plugin.yml") {
             expand(inputs.properties)
@@ -188,9 +180,35 @@ tasks {
     }
 }
 
-/**
- * Gradle is weird sometimes, we need to delete the plugin yml from the build folder to actually filter properly.
- */
-afterEvaluate {
-    layout.buildDirectory.file("resources/main/plugin.yml").get().asFile.delete()
+val templateSource = file("src/main/templates")
+val templateDest = layout.buildDirectory.dir("generated/sources/templates")
+val generateTemplates = tasks.register<Copy>("generateTemplates") {
+    inputs.properties(
+        "environment" to if (project.hasProperty("release")) "production" else "development",
+        "commit" to provider {
+            val res = runCatching { project.extensions.getByType<Grgit>().head().id }
+            res.getOrDefault("")
+                .takeIf { it.length == 40 } ?: {
+                logger.error("Git commit hash not found", res.exceptionOrNull())
+                "unknown"
+            }()
+        },
+    )
+
+    from(templateSource)
+    into(templateDest)
+    rename { "com/volmit/iris/$it" }
+    expand(inputs.properties)
+}
+
+tasks.generateSentryBundleIdJava {
+    dependsOn(generateTemplates)
+}
+
+rootProject.tasks.named("prepareKotlinBuildScriptModel") {
+    dependsOn(generateTemplates)
+}
+
+sourceSets.main {
+    java.srcDir(generateTemplates.map { it.outputs })
 }

core/src/main/java/com/volmit/iris/Iris.java

@@ -715,7 +715,11 @@ public class Iris extends VolmitPlugin implements Listener {
         Iris.debug("Generator Config: " + w.toString());
 
         File ff = new File(w.worldFolder(), "iris/pack");
-        if (!ff.exists() || ff.listFiles().length == 0) {
+        var files = ff.listFiles();
+        if (files == null || files.length == 0)
+            IO.delete(ff);
+
+        if (!ff.exists()) {
             ff.mkdirs();
             service(StudioSVC.class).installIntoWorld(getSender(), dim.getLoadKey(), w.worldFolder());
         }
@@ -725,13 +729,13 @@ public class Iris extends VolmitPlugin implements Listener {
 
     @Nullable
     public static IrisDimension loadDimension(@NonNull String worldName, @NonNull String id) {
-        var data = IrisData.get(new File(Bukkit.getWorldContainer(), String.join(File.separator, worldName, "iris", "pack")));
-        var dimension = data.getDimensionLoader().load(id);
-        if (dimension == null) dimension = IrisData.loadAnyDimension(id);
+        File pack = new File(Bukkit.getWorldContainer(), String.join(File.separator, worldName, "iris", "pack"));
+        var dimension = pack.isDirectory() ? IrisData.get(pack).getDimensionLoader().load(id) : null;
+        if (dimension == null) dimension = IrisData.loadAnyDimension(id, null);
         if (dimension == null) {
             Iris.warn("Unable to find dimension type " + id + " Looking for online packs...");
             Iris.service(StudioSVC.class).downloadSearch(new VolmitSender(Bukkit.getConsoleSender()), id, false);
-            dimension = IrisData.loadAnyDimension(id);
+            dimension = IrisData.loadAnyDimension(id, null);
 
             if (dimension != null) {
                 Iris.info("Resolved missing dimension, proceeding.");

core/src/main/java/com/volmit/iris/core/IrisSettings.java

@@ -244,6 +244,7 @@ public class IrisSettings {
         public boolean preventLeafDecay = true;
         public boolean useMulticore = false;
         public boolean offsetNoiseTypes = false;
+        public boolean earlyCustomBlocks = false;
     }
 
     @Data

core/src/main/java/com/volmit/iris/core/IrisWorlds.java

@@ -66,6 +66,7 @@ public class IrisWorlds {
     }
 
     public KMap<String, String> getWorlds() {
+        clean();
         return readBukkitWorlds().put(worlds);
     }
 
@@ -76,8 +77,7 @@ public class IrisWorlds {
     }
 
     public Stream<IrisDimension> getDimensions() {
-        return readBukkitWorlds()
-                .put(worlds)
+        return getWorlds()
                 .entrySet()
                 .stream()
                 .map(entry -> Iris.loadDimension(entry.getKey(), entry.getValue()))

core/src/main/java/com/volmit/iris/core/ServerConfigurator.java

@@ -103,14 +103,14 @@ public class ServerConfigurator {
         return worlds;
     }
 
-    public static void installDataPacks(boolean fullInstall) {
-        installDataPacks(DataVersion.getDefault(), fullInstall);
+    public static boolean installDataPacks(boolean fullInstall) {
+        return installDataPacks(DataVersion.getDefault(), fullInstall);
     }
 
-    public static void installDataPacks(IDataFixer fixer, boolean fullInstall) {
+    public static boolean installDataPacks(IDataFixer fixer, boolean fullInstall) {
         if (fixer == null) {
             Iris.error("Unable to install datapacks, fixer is null!");
-            return;
+            return false;
         }
         Iris.info("Checking Data Packs...");
         DimensionHeight height = new DimensionHeight(fixer);
@@ -129,11 +129,10 @@ public class ServerConfigurator {
         IrisDimension.writeShared(folders, height);
         Iris.info("Data Packs Setup!");
 
-        if (fullInstall)
-            verifyDataPacksPost(IrisSettings.get().getAutoConfiguration().isAutoRestartOnCustomBiomeInstall());
+        return fullInstall && verifyDataPacksPost(IrisSettings.get().getAutoConfiguration().isAutoRestartOnCustomBiomeInstall());
     }
 
-    private static void verifyDataPacksPost(boolean allowRestarting) {
+    private static boolean verifyDataPacksPost(boolean allowRestarting) {
         try (Stream<IrisData> stream = allPacks()) {
             boolean bad = stream
                     .map(data -> {
@@ -148,7 +147,7 @@ public class ServerConfigurator {
                     })
                     .toList()
                     .contains(true);
-            if (!bad) return;
+            if (!bad) return false;
         }
 
 
@@ -172,6 +171,7 @@ public class ServerConfigurator {
 
             J.sleep(3000);
         }
+        return true;
     }
 
     public static void restart() {

core/src/main/java/com/volmit/iris/core/commands/CommandDeveloper.java

@@ -18,19 +18,29 @@
 
 package com.volmit.iris.core.commands;
 
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.ServerConfigurator;
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.core.nms.INMS;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.core.service.IrisEngineSVC;
 import com.volmit.iris.core.tools.IrisPackBenchmarking;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.object.IrisDimension;
+import com.volmit.iris.engine.object.annotations.Snippet;
+import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.context.IrisContext;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.decree.DecreeExecutor;
 import com.volmit.iris.util.decree.DecreeOrigin;
 import com.volmit.iris.util.decree.annotations.Decree;
 import com.volmit.iris.util.decree.annotations.Param;
+import com.volmit.iris.util.decree.specialhandlers.NullableDimensionHandler;
 import com.volmit.iris.util.format.C;
 import com.volmit.iris.util.format.Form;
 import com.volmit.iris.util.io.CountingDataInputStream;
@@ -42,6 +52,7 @@ import com.volmit.iris.util.nbt.mca.MCAFile;
 import com.volmit.iris.util.nbt.mca.MCAUtil;
 import com.volmit.iris.util.parallel.MultiBurst;
 import com.volmit.iris.util.plugin.VolmitSender;
+import lombok.SneakyThrows;
 import net.jpountz.lz4.LZ4BlockInputStream;
 import net.jpountz.lz4.LZ4BlockOutputStream;
 import net.jpountz.lz4.LZ4FrameInputStream;
@@ -59,6 +70,7 @@ import java.util.*;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 import java.util.zip.GZIPInputStream;
 import java.util.zip.GZIPOutputStream;
 
@@ -143,6 +155,130 @@ public class CommandDeveloper implements DecreeExecutor {
         }
     }
 
+    @SneakyThrows
+    @Decree(description = "Generate Iris structures for all loaded datapack structures")
+    public void generateStructures(
+            @Param(description = "The pack to add the generated structures to", aliases = "pack", defaultValue = "null", customHandler = NullableDimensionHandler.class)
+            IrisDimension dimension,
+            @Param(description = "Ignore existing structures", defaultValue = "false")
+            boolean force
+    ) {
+        var map = INMS.get().collectStructures();
+        if (map.isEmpty()) {
+            sender().sendMessage(C.IRIS + "No structures found");
+            return;
+        }
+
+        sender().sendMessage(C.IRIS + "Found " + map.size() + " structures");
+
+        final File dataDir;
+        final IrisData data;
+        final Set<String> existingStructures;
+        final Map<String, Set<String>> snippets;
+        final File dimensionFile;
+        final File structuresFolder;
+        final File snippetsFolder;
+
+        var dimensionObj = new JsonObject();
+
+        if (dimension == null) {
+            dataDir = Iris.instance.getDataFolder("structures");
+            IO.delete(dataDir);
+            data = IrisData.get(dataDir);
+            existingStructures = Set.of();
+            snippets = Map.of();
+            dimensionFile = new File(dataDir, "structures.json");
+        } else {
+            data = dimension.getLoader();
+            dataDir = data.getDataFolder();
+            existingStructures = new KSet<>(data.getJigsawStructureLoader().getPossibleKeys());
+
+            dimensionObj = data.getGson().fromJson(IO.readAll(dimension.getLoadFile()), JsonObject.class);
+            snippets = Optional.ofNullable(dimensionObj.getAsJsonArray("jigsawStructures"))
+                    .map(array -> array.asList()
+                            .stream()
+                            .filter(JsonElement::isJsonPrimitive)
+                            .collect(Collectors.toMap(element -> data.getGson()
+                                            .fromJson(element, IrisJigsawStructurePlacement.class)
+                                            .getStructure(),
+                                    element -> Set.of(element.getAsString()),
+                                    KSet::merge)))
+                    .orElse(Map.of());
+
+            dimensionFile = dimension.getLoadFile();
+        }
+        structuresFolder = new File(dataDir, "jigsaw-structures");
+        snippetsFolder = new File(dataDir, "snippet" + "/" + IrisJigsawStructurePlacement.class.getAnnotation(Snippet.class).value());
+
+        var gson = data.getGson();
+        var jigsawStructures = Optional.ofNullable(dimensionObj.getAsJsonArray("jigsawStructures"))
+                .orElse(new JsonArray(map.size()));
+
+        map.forEach((key, placement) -> {
+            String loadKey = "datapack/" + key.namespace() + "/" + key.key();
+            if (existingStructures.contains(loadKey) && !force)
+                return;
+
+            var structures = placement.structures();
+            var obj = placement.toJson(loadKey);
+            if (obj == null || structures.isEmpty()) {
+                sender().sendMessage(C.RED + "Failed to generate hook for " + key);
+                return;
+            }
+            File snippetFile = new File(snippetsFolder, loadKey + ".json");
+            try {
+                IO.writeAll(snippetFile, gson.toJson(obj));
+            } catch (IOException e) {
+                sender().sendMessage(C.RED + "Failed to generate snippet for " + key);
+                e.printStackTrace();
+                return;
+            }
+
+            Set<String> loadKeys = snippets.getOrDefault(loadKey, Set.of(loadKey));
+            jigsawStructures.asList().removeIf(e -> loadKeys.contains((e.isJsonObject() ? e.getAsJsonObject().get("structure") : e).getAsString()));
+            jigsawStructures.add("snippet/" + loadKey);
+
+            String structureKey;
+            if (structures.size() > 1) {
+                KList<String> common = new KList<>();
+                for (int i = 0; i < structures.size(); i++) {
+                    var tags = structures.get(i).tags();
+                    if (i == 0) common.addAll(tags);
+                    else common.removeIf(tag -> !tags.contains(tag));
+                }
+                structureKey = common.isNotEmpty() ? "#" + common.getFirst() : structures.getFirst().key();
+            } else structureKey = structures.getFirst().key();
+
+            JsonArray array = new JsonArray();
+            if (structures.size() > 1) {
+                structures.stream()
+                        .flatMap(structure -> {
+                            String[] arr = new String[structure.weight()];
+                            Arrays.fill(arr, structure.key());
+                            return Arrays.stream(arr);
+                        })
+                        .forEach(array::add);
+            } else array.add(structureKey);
+
+            obj = new JsonObject();
+            obj.addProperty("structureKey", structureKey);
+            obj.add("datapackStructures", array);
+
+            File out = new File(structuresFolder, loadKey + ".json");
+            out.getParentFile().mkdirs();
+            try {
+                IO.writeAll(out, gson.toJson(obj));
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        });
+
+        dimensionObj.add("jigsawStructures", jigsawStructures);
+        IO.writeAll(dimensionFile, gson.toJson(dimensionObj));
+
+        data.hotloaded();
+    }
+
     @Decree(description = "Test")
     public void packBenchmark(
             @Param(description = "The pack to bench", aliases = {"pack"}, defaultValue = "overworld")

core/src/main/java/com/volmit/iris/core/commands/CommandJigsaw.java

@@ -48,7 +48,7 @@ public class CommandJigsaw implements DecreeExecutor {
             IrisJigsawPiece piece
     ) {
         File dest = piece.getLoadFile();
-        new JigsawEditor(player(), piece, IrisData.loadAnyObject(piece.getObject()), dest);
+        new JigsawEditor(player(), piece, IrisData.loadAnyObject(piece.getObject(), data()), dest);
     }
 
     @Decree(description = "Place a jigsaw structure")
@@ -78,7 +78,7 @@ public class CommandJigsaw implements DecreeExecutor {
             @Param(description = "The object to use for this piece", customHandler = ObjectHandler.class)
             String object
     ) {
-        IrisObject o = IrisData.loadAnyObject(object);
+        IrisObject o = IrisData.loadAnyObject(object, data());
 
         if (object == null) {
             sender().sendMessage(C.RED + "Failed to find existing object");

core/src/main/java/com/volmit/iris/core/commands/CommandObject.java

@@ -136,7 +136,7 @@ public class CommandObject implements DecreeExecutor {
             @Param(description = "The object to analyze", customHandler = ObjectHandler.class)
             String object
     ) {
-        IrisObject o = IrisData.loadAnyObject(object);
+        IrisObject o = IrisData.loadAnyObject(object, data());
         sender().sendMessage("Object Size: " + o.getW() + " * " + o.getH() + " * " + o.getD() + "");
         sender().sendMessage("Blocks Used: " + NumberFormat.getIntegerInstance().format(o.getBlocks().size()));
 
@@ -201,7 +201,7 @@ public class CommandObject implements DecreeExecutor {
 
     @Decree(description = "Shrink an object to its minimum size")
     public void shrink(@Param(description = "The object to shrink", customHandler = ObjectHandler.class) String object) {
-        IrisObject o = IrisData.loadAnyObject(object);
+        IrisObject o = IrisData.loadAnyObject(object, data());
         sender().sendMessage("Current Object Size: " + o.getW() + " * " + o.getH() + " * " + o.getD());
         o.shrinkwrap();
         sender().sendMessage("New Object Size: " + o.getW() + " * " + o.getH() + " * " + o.getD());
@@ -325,7 +325,7 @@ public class CommandObject implements DecreeExecutor {
 //            @Param(description = "The scale interpolator to use", defaultValue = "none")
 //            IrisObjectPlacementScaleInterpolator interpolator
     ) {
-        IrisObject o = IrisData.loadAnyObject(object);
+        IrisObject o = IrisData.loadAnyObject(object, data());
         double maxScale = Double.max(10 - o.getBlocks().size() / 10000d, 1);
         if (scale > maxScale) {
             sender().sendMessage(C.YELLOW + "Indicated scale exceeds maximum. Downscaled to maximum: " + maxScale);

core/src/main/java/com/volmit/iris/core/commands/CommandStudio.java

@@ -171,9 +171,9 @@ public class CommandStudio implements DecreeExecutor {
         var loc = player().getLocation().clone();
 
         J.a(() -> {
-            DecreeContext.touch(sender);
             PlatformChunkGenerator plat = IrisToolbelt.access(world);
             Engine engine = plat.getEngine();
+            DecreeContext.touch(sender);
             try (SyncExecutor executor = new SyncExecutor(20)) {
                 int x = loc.getBlockX() >> 4;
                 int z = loc.getBlockZ() >> 4;
@@ -247,6 +247,8 @@ public class CommandStudio implements DecreeExecutor {
             } catch (Throwable e) {
                 sender().sendMessage("Error while regenerating chunks");
                 e.printStackTrace();
+            } finally {
+                DecreeContext.remove();
             }
         });
     }

core/src/main/java/com/volmit/iris/core/link/data/ItemAdderDataProvider.java

@@ -62,7 +62,10 @@ public class ItemAdderDataProvider extends ExternalDataProvider {
 
     @Override
     public void processUpdate(@NotNull Engine engine, @NotNull Block block, @NotNull Identifier blockId) {
-        CustomBlock.place(blockId.toString(), block.getLocation());
+        CustomBlock custom;
+        if ((custom = CustomBlock.place(blockId.toString(), block.getLocation())) == null)
+            return;
+        block.setBlockData(custom.getBaseBlockData(), false);
     }
 
     @Override

core/src/main/java/com/volmit/iris/core/link/data/MythicMobsDataProvider.java

@@ -5,10 +5,14 @@ import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import io.lumine.mythic.api.adapters.AbstractLocation;
 import io.lumine.mythic.api.config.MythicLineConfig;
+import io.lumine.mythic.api.mobs.entities.SpawnReason;
 import io.lumine.mythic.api.skills.conditions.ILocationCondition;
+import io.lumine.mythic.bukkit.BukkitAdapter;
 import io.lumine.mythic.bukkit.MythicBukkit;
 import io.lumine.mythic.bukkit.adapters.BukkitWorld;
 import io.lumine.mythic.bukkit.events.MythicConditionLoadEvent;
+import io.lumine.mythic.core.mobs.ActiveMob;
+import io.lumine.mythic.core.mobs.MobStack;
 import io.lumine.mythic.core.skills.SkillCondition;
 import io.lumine.mythic.core.utils.annotations.MythicCondition;
 import io.lumine.mythic.core.utils.annotations.MythicField;
@@ -17,10 +21,10 @@ import org.bukkit.entity.Entity;
 import org.bukkit.event.EventHandler;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Stream;
 
 public class MythicMobsDataProvider extends ExternalDataProvider {
     public MythicMobsDataProvider() {
@@ -33,18 +37,31 @@ public class MythicMobsDataProvider extends ExternalDataProvider {
 
     @Override
     public @Nullable Entity spawnMob(@NotNull Location location, @NotNull Identifier entityId) throws MissingResourceException {
-        var mm = MythicBukkit.inst().getMobManager().spawnMob(entityId.key(), location);
-        if (mm == null) throw new MissingResourceException("Failed to find mob!", entityId.namespace(), entityId.key());
-        return mm.getEntity().getBukkitEntity();
+        var mm = spawnMob(BukkitAdapter.adapt(location), entityId);
+        return mm == null ? null : mm.getEntity().getBukkitEntity();
+    }
+
+    private ActiveMob spawnMob(AbstractLocation location, Identifier entityId) throws MissingResourceException {
+        var manager = MythicBukkit.inst().getMobManager();
+        var mm = manager.getMythicMob(entityId.key()).orElse(null);
+        if (mm == null) {
+            var stack = manager.getMythicMobStack(entityId.key());
+            if (stack == null) throw new MissingResourceException("Failed to find Mob!", entityId.namespace(), entityId.key());
+            return stack.spawn(location, 1d, SpawnReason.OTHER, null);
+        }
+        return mm.spawn(location, 1d, SpawnReason.OTHER, null, null);
     }
 
     @Override
     public @NotNull Collection<@NotNull Identifier> getTypes(@NotNull DataType dataType) {
         if (dataType != DataType.ENTITY) return List.of();
-        return MythicBukkit.inst()
-                .getMobManager()
-                .getMobNames()
+        var manager = MythicBukkit.inst().getMobManager();
+        return Stream.concat(manager.getMobNames().stream(),
+                        manager.getMobStacks()
                                 .stream()
+                                .map(MobStack::getName)
+                )
+                .distinct()
                 .map(name -> new Identifier("mythicmobs", name))
                 .toList();
     }

core/src/main/java/com/volmit/iris/core/loader/IrisData.java

@@ -43,6 +43,7 @@ import com.volmit.iris.util.reflect.KeyedType;
 import com.volmit.iris.util.scheduling.ChronoLatch;
 import com.volmit.iris.util.scheduling.J;
 import lombok.Data;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
 import java.io.FileReader;
@@ -50,7 +51,7 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Objects;
-import java.util.function.Function;
+import java.util.Optional;
 
 @Data
 public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
@@ -99,6 +100,10 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
         return dataLoaders.computeIfAbsent(dataFolder, IrisData::new);
     }
 
+    public static Optional<IrisData> getLoaded(File dataFolder) {
+        return Optional.ofNullable(dataLoaders.get(dataFolder));
+    }
+
     public static void dereference() {
         dataLoaders.v().forEach(IrisData::cleanupEngine);
     }
@@ -118,92 +123,100 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
         Iris.warn("  " + rl.getResourceTypeName() + " @ /" + rl.getFolderName() + ": Cache=" + rl.getLoadCache().getSize() + " Folders=" + rl.getFolders().size());
     }
 
-    public static IrisObject loadAnyObject(String key) {
-        return loadAny(key, (dm) -> dm.getObjectLoader().load(key, false));
+    public static IrisObject loadAnyObject(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisObject.class, key, nearest);
     }
 
-    public static IrisMatterObject loadAnyMatter(String key) {
-        return loadAny(key, (dm) -> dm.getMatterLoader().load(key, false));
+    public static IrisMatterObject loadAnyMatter(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisMatterObject.class, key, nearest);
     }
 
-    public static IrisBiome loadAnyBiome(String key) {
-        return loadAny(key, (dm) -> dm.getBiomeLoader().load(key, false));
+    public static IrisBiome loadAnyBiome(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisBiome.class, key, nearest);
     }
 
-    public static IrisExpression loadAnyExpression(String key) {
-        return loadAny(key, (dm) -> dm.getExpressionLoader().load(key, false));
+    public static IrisExpression loadAnyExpression(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisExpression.class, key, nearest);
     }
 
-    public static IrisMod loadAnyMod(String key) {
-        return loadAny(key, (dm) -> dm.getModLoader().load(key, false));
+    public static IrisMod loadAnyMod(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisMod.class, key, nearest);
     }
 
-    public static IrisJigsawPiece loadAnyJigsawPiece(String key) {
-        return loadAny(key, (dm) -> dm.getJigsawPieceLoader().load(key, false));
+    public static IrisJigsawPiece loadAnyJigsawPiece(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisJigsawPiece.class, key, nearest);
     }
 
-    public static IrisJigsawPool loadAnyJigsawPool(String key) {
-        return loadAny(key, (dm) -> dm.getJigsawPoolLoader().load(key, false));
+    public static IrisJigsawPool loadAnyJigsawPool(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisJigsawPool.class, key, nearest);
     }
 
-    public static IrisEntity loadAnyEntity(String key) {
-        return loadAny(key, (dm) -> dm.getEntityLoader().load(key, false));
+    public static IrisEntity loadAnyEntity(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisEntity.class, key, nearest);
     }
 
-    public static IrisLootTable loadAnyLootTable(String key) {
-        return loadAny(key, (dm) -> dm.getLootLoader().load(key, false));
+    public static IrisLootTable loadAnyLootTable(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisLootTable.class, key, nearest);
     }
 
-    public static IrisBlockData loadAnyBlock(String key) {
-        return loadAny(key, (dm) -> dm.getBlockLoader().load(key, false));
+    public static IrisBlockData loadAnyBlock(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisBlockData.class, key, nearest);
     }
 
-    public static IrisSpawner loadAnySpaner(String key) {
-        return loadAny(key, (dm) -> dm.getSpawnerLoader().load(key, false));
+    public static IrisSpawner loadAnySpaner(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisSpawner.class, key, nearest);
     }
 
-    public static IrisScript loadAnyScript(String key) {
-        return loadAny(key, (dm) -> dm.getScriptLoader().load(key, false));
+    public static IrisScript loadAnyScript(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisScript.class, key, nearest);
     }
 
-    public static IrisRavine loadAnyRavine(String key) {
-        return loadAny(key, (dm) -> dm.getRavineLoader().load(key, false));
+    public static IrisRavine loadAnyRavine(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisRavine.class, key, nearest);
     }
 
-    public static IrisRegion loadAnyRegion(String key) {
-        return loadAny(key, (dm) -> dm.getRegionLoader().load(key, false));
+    public static IrisRegion loadAnyRegion(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisRegion.class, key, nearest);
     }
 
-    public static IrisMarker loadAnyMarker(String key) {
-        return loadAny(key, (dm) -> dm.getMarkerLoader().load(key, false));
+    public static IrisMarker loadAnyMarker(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisMarker.class, key, nearest);
     }
 
-    public static IrisCave loadAnyCave(String key) {
-        return loadAny(key, (dm) -> dm.getCaveLoader().load(key, false));
+    public static IrisCave loadAnyCave(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisCave.class, key, nearest);
     }
 
-    public static IrisImage loadAnyImage(String key) {
-        return loadAny(key, (dm) -> dm.getImageLoader().load(key, false));
+    public static IrisImage loadAnyImage(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisImage.class, key, nearest);
     }
 
-    public static IrisDimension loadAnyDimension(String key) {
-        return loadAny(key, (dm) -> dm.getDimensionLoader().load(key, false));
+    public static IrisDimension loadAnyDimension(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisDimension.class, key, nearest);
     }
 
-    public static IrisJigsawStructure loadAnyJigsawStructure(String key) {
-        return loadAny(key, (dm) -> dm.getJigsawStructureLoader().load(key, false));
+    public static IrisJigsawStructure loadAnyJigsawStructure(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisJigsawStructure.class, key, nearest);
     }
 
-    public static IrisGenerator loadAnyGenerator(String key) {
-        return loadAny(key, (dm) -> dm.getGeneratorLoader().load(key, false));
+    public static IrisGenerator loadAnyGenerator(String key, @Nullable IrisData nearest) {
+        return loadAny(IrisGenerator.class, key, nearest);
     }
 
-    public static <T extends IrisRegistrant> T loadAny(String key, Function<IrisData, T> v) {
+    public static <T extends IrisRegistrant> T loadAny(Class<T> type, String key, @Nullable IrisData nearest) {
         try {
+            if (nearest != null) {
+                T t = nearest.load(type, key, false);
+                if (t != null) {
+                    return t;
+                }
+            }
+
             for (File i : Objects.requireNonNull(Iris.instance.getDataFolder("packs").listFiles())) {
                 if (i.isDirectory()) {
                     IrisData dm = get(i);
-                    T t = v.apply(dm);
+                    if (dm == nearest) continue;
+                    T t = dm.load(type, key, false);
 
                     if (t != null) {
                         return t;
@@ -218,6 +231,17 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
         return null;
     }
 
+    public <T extends IrisRegistrant> T load(Class<T> type, String key, boolean warn) {
+        var loader = getLoader(type);
+        if (loader == null) return null;
+        return loader.load(key, warn);
+    }
+
+    @SuppressWarnings("unchecked")
+    public <T extends IrisRegistrant> ResourceLoader<T> getLoader(Class<T> type) {
+        return (ResourceLoader<T>) loaders.get(type);
+    }
+
     public ResourceLoader<?> getTypedLoaderFor(File f) {
         String[] k = f.getPath().split("\\Q" + File.separator + "\\E");
 
@@ -325,6 +349,7 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
     }
 
     public synchronized void hotloaded() {
+        closed = false;
         environment.close();
         possibleSnippets = new KMap<>();
         builder = new GsonBuilder()
@@ -425,6 +450,7 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
         }
 
         String snippetType = typeToken.getRawType().getDeclaredAnnotation(Snippet.class).value();
+        String snippedBase = "snippet/" + snippetType + "/";
 
         return new TypeAdapter<>() {
             @Override
@@ -438,10 +464,12 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
 
                 if (reader.peek().equals(JsonToken.STRING)) {
                     String r = reader.nextString();
+                    if (!r.startsWith("snippet/"))
+                        return null;
+                    if (!r.startsWith(snippedBase))
+                        r = snippedBase + r.substring(8);
 
-                    if (r.startsWith("snippet/" + snippetType + "/")) {
                     File f = new File(getDataFolder(), r + ".json");
-
                     if (f.exists()) {
                         try (JsonReader snippetReader = new JsonReader(new FileReader(f))){
                             return adapter.read(snippetReader);
@@ -451,7 +479,6 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
                     } else {
                         Iris.error("Couldn't find snippet " + r + " in " + reader.getPath());
                     }
-                    }
 
                     return null;
                 }
@@ -488,7 +515,7 @@ public class IrisData implements ExclusionStrategy, TypeAdapterFactory {
                         .map(s -> s.substring(absPath.length() + 1))
                         .map(s -> s.replace("\\", "/"))
                         .map(s -> s.split("\\Q.\\E")[0])
-                        .forEach(s -> l.add("snippet/" + f + "/" + s));
+                        .forEach(s -> l.add("snippet/" + s));
             } catch (Throwable e) {
                 e.printStackTrace();
             }

core/src/main/java/com/volmit/iris/core/loader/IrisRegistrant.java

@@ -28,6 +28,7 @@ import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.json.JSONObject;
 import com.volmit.iris.util.plugin.VolmitSender;
 import lombok.Data;
+import lombok.EqualsAndHashCode;
 
 import java.awt.*;
 import java.io.File;
@@ -39,6 +40,7 @@ public abstract class IrisRegistrant {
     @ArrayType(min = 1, type = String.class)
     private KList<String> preprocessors = new KList<>();
 
+    @EqualsAndHashCode.Exclude
     private transient IrisData loader;
 
     private transient String loadKey;

core/src/main/java/com/volmit/iris/core/nms/INMSBinding.java

@@ -18,9 +18,13 @@
 
 package com.volmit.iris.core.nms;
 
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.link.FoliaWorldsLink;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
@@ -147,4 +151,8 @@ public interface INMSBinding {
     }
 
     KMap<Material, List<BlockProperty>> getBlockProperties();
+
+    void placeStructures(Chunk chunk);
+
+    KMap<Identifier, StructurePlacement> collectStructures();
 }

core/src/main/java/com/volmit/iris/core/nms/container/StructurePlacement.java

@@ -0,0 +1,77 @@
+package com.volmit.iris.core.nms.container;
+
+import com.google.gson.JsonObject;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement.SpreadType;
+import lombok.*;
+import lombok.experimental.Accessors;
+import lombok.experimental.SuperBuilder;
+import org.apache.commons.math3.fraction.Fraction;
+
+import java.util.List;
+
+@Data
+@SuperBuilder
+@Accessors(fluent = true, chain = true)
+public abstract class StructurePlacement {
+    private final int salt;
+    private final float frequency;
+    private final List<Structure> structures;
+
+    public abstract JsonObject toJson(String structure);
+
+    protected JsonObject createBase(String structure) {
+        JsonObject object = new JsonObject();
+        object.addProperty("structure", structure);
+        object.addProperty("salt", salt);
+        return object;
+    }
+
+    public int frequencyToSpacing() {
+        var frac = new Fraction(Math.max(Math.min(frequency, 1), 0.000000001f));
+        return (int) Math.round(Math.sqrt((double) frac.getDenominator() / frac.getNumerator()));
+    }
+
+    @Getter
+    @Accessors(chain = true, fluent = true)
+    @EqualsAndHashCode(callSuper = true)
+    @SuperBuilder
+    public static class RandomSpread extends StructurePlacement {
+        private final int spacing;
+        private final int separation;
+        private final SpreadType spreadType;
+
+        @Override
+        public JsonObject toJson(String structure) {
+            JsonObject object = createBase(structure);
+            object.addProperty("spacing", Math.max(spacing, frequencyToSpacing()));
+            object.addProperty("separation", separation);
+            object.addProperty("spreadType", spreadType.name());
+            return object;
+        }
+    }
+
+    @Getter
+    @EqualsAndHashCode(callSuper = true)
+    @SuperBuilder
+    public static class ConcentricRings extends StructurePlacement {
+        private final int distance;
+        private final int spread;
+        private final int count;
+
+        @Override
+        public JsonObject toJson(String structure) {
+            return null;
+        }
+    }
+
+    public record Structure(
+            int weight,
+            String key,
+            List<String> tags
+    ) {
+
+        public boolean isValid() {
+            return weight > 0 && key != null;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/nms/v1X/NMSBinding1X.java

@@ -19,10 +19,13 @@
 package com.volmit.iris.core.nms.v1X;
 
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
@@ -135,6 +138,16 @@ public class NMSBinding1X implements INMSBinding {
         return map;
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        return new KMap<>();
+    }
+
     @Override
     public CompoundTag serializeEntity(Entity location) {
         return null;

core/src/main/java/com/volmit/iris/core/project/IrisProject.java

@@ -159,7 +159,7 @@ public class IrisProject {
 
     public void openVSCode(VolmitSender sender) {
 
-        IrisDimension d = IrisData.loadAnyDimension(getName());
+        IrisDimension d = IrisData.loadAnyDimension(getName(), null);
         J.attemptAsync(() ->
         {
             try {
@@ -221,7 +221,7 @@ public class IrisProject {
         }
 
         J.a(() -> {
-            IrisDimension d = IrisData.loadAnyDimension(getName());
+            IrisDimension d = IrisData.loadAnyDimension(getName(), null);
             if (d == null) {
                 sender.sendMessage("Can't find dimension: " + getName());
                 return;

core/src/main/java/com/volmit/iris/core/service/BoardSVC.java

@@ -22,33 +22,39 @@ import com.volmit.iris.Iris;
 import com.volmit.iris.core.IrisSettings;
 import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.tools.IrisToolbelt;
-import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.util.board.BoardManager;
 import com.volmit.iris.util.board.BoardProvider;
 import com.volmit.iris.util.board.BoardSettings;
 import com.volmit.iris.util.board.ScoreDirection;
-import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.format.C;
 import com.volmit.iris.util.format.Form;
 import com.volmit.iris.util.plugin.IrisService;
 import com.volmit.iris.util.scheduling.J;
 import lombok.Data;
+import org.bukkit.Location;
+import org.bukkit.World;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.player.PlayerChangedWorldEvent;
 import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
 
+import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
 
 public class BoardSVC implements IrisService, BoardProvider {
     private final KMap<Player, PlayerBoard> boards = new KMap<>();
-    private com.volmit.iris.util.board.BoardManager manager;
+    private ScheduledExecutorService executor;
+    private BoardManager manager;
 
     @Override
     public void onEnable() {
-        J.ar(this::tick, 20);
+        executor = Executors.newScheduledThreadPool(0, Thread.ofVirtual().factory());
         manager = new BoardManager(Iris.instance, BoardSettings.builder()
                 .boardProvider(this)
                 .scoreDirection(ScoreDirection.DOWN)
@@ -57,6 +63,7 @@ public class BoardSVC implements IrisService, BoardProvider {
 
     @Override
     public void onDisable() {
+        executor.shutdownNow();
         manager.onDisable();
         boards.clear();
     }
@@ -71,14 +78,22 @@ public class BoardSVC implements IrisService, BoardProvider {
         J.s(() -> updatePlayer(e.getPlayer()));
     }
 
+    @EventHandler
+    public void on(PlayerQuitEvent e) {
+        remove(e.getPlayer());
+    }
+
     public void updatePlayer(Player p) {
         if (IrisToolbelt.isIrisStudioWorld(p.getWorld())) {
             manager.remove(p);
             manager.setup(p);
-        } else {
-            manager.remove(p);
-            boards.remove(p);
+        } else remove(p);
     }
+
+    private void remove(Player player) {
+        manager.remove(player);
+        var board = boards.remove(player);
+        if (board != null) board.task.cancel(true);
     }
 
     @Override
@@ -86,52 +101,55 @@ public class BoardSVC implements IrisService, BoardProvider {
         return C.GREEN + "Iris";
     }
 
-    public void tick() {
+    @Override
+    public List<String> getLines(Player player) {
+        return boards.computeIfAbsent(player, PlayerBoard::new).lines;
+    }
+
+    @Data
+    public class PlayerBoard {
+        private final Player player;
+        private final ScheduledFuture<?> task;
+        private volatile List<String> lines;
+
+        public PlayerBoard(Player player) {
+            this.player = player;
+            this.lines = new ArrayList<>();
+            this.task = executor.scheduleAtFixedRate(this::tick, 0, 1, TimeUnit.SECONDS);
+        }
+
+        private void tick() {
             if (!Iris.service(StudioSVC.class).isProjectOpen()) {
                 return;
             }
 
-        boards.forEach((k, v) -> v.update());
-    }
-
-    @Override
-    public List<String> getLines(Player player) {
-        PlayerBoard pb = boards.computeIfAbsent(player, PlayerBoard::new);
-        synchronized (pb.lines) {
-            return pb.lines;
-        }
-    }
-
-    @Data
-    public static class PlayerBoard {
-        private final Player player;
-        private final CopyOnWriteArrayList<String> lines;
-
-        public PlayerBoard(Player player) {
-            this.player = player;
-            this.lines = new CopyOnWriteArrayList<>();
             update();
         }
 
         public void update() {
-            synchronized (lines) {
-                lines.clear();
+            final World world = player.getWorld();
+            final Location loc = player.getLocation();
 
-                if (!IrisToolbelt.isIrisStudioWorld(player.getWorld())) {
-                    return;
-                }
+            final var access = IrisToolbelt.access(world);
+            if (access == null) return;
 
-                Engine engine = IrisToolbelt.access(player.getWorld()).getEngine();
-                int x = player.getLocation().getBlockX();
-                int y = player.getLocation().getBlockY() - player.getWorld().getMinHeight();
-                int z = player.getLocation().getBlockZ();
+            final var engine = access.getEngine();
+            if (engine == null) return;
+
+            int x = loc.getBlockX();
+            int y = loc.getBlockY() - world.getMinHeight();
+            int z = loc.getBlockZ();
+
+            List<String> lines = new ArrayList<>(this.lines.size());
+            lines.add("&7&m                   ");
+            lines.add(C.GREEN + "Speed" + C.GRAY + ":  " + Form.f(engine.getGeneratedPerSecond(), 0) + "/s " + Form.duration(1000D / engine.getGeneratedPerSecond(), 0));
+            lines.add(C.AQUA + "Cache" + C.GRAY + ": " + Form.f(IrisData.cacheSize()));
+            lines.add(C.AQUA + "Mantle" + C.GRAY + ": " + engine.getMantle().getLoadedRegionCount());
 
             if (IrisSettings.get().getGeneral().debug) {
-                    lines.add("&7&m                   ");
-                    lines.add(C.GREEN + "Speed" + C.GRAY + ":  " + Form.f(engine.getGeneratedPerSecond(), 0) + "/s " + Form.duration(1000D / engine.getGeneratedPerSecond(), 0));
-                    lines.add(C.AQUA + "Cache" + C.GRAY + ": " + Form.f(IrisData.cacheSize()));
-                    lines.add(C.AQUA + "Mantle" + C.GRAY + ": " + engine.getMantle().getLoadedRegionCount());
                 lines.add(C.LIGHT_PURPLE + "Carving" + C.GRAY + ": " + engine.getMantle().isCarved(x,y,z));
+            }
+
             lines.add("&7&m                   ");
             lines.add(C.AQUA + "Region" + C.GRAY + ": " + engine.getRegion(x, z).getName());
             lines.add(C.AQUA + "Biome" + C.GRAY + ":  " + engine.getBiomeOrMantle(x, y, z).getName());
@@ -139,20 +157,7 @@ public class BoardSVC implements IrisService, BoardProvider {
             lines.add(C.AQUA + "Slope" + C.GRAY + ":  " + Form.f(engine.getComplex().getSlopeStream().get(x, z), 2));
             lines.add(C.AQUA + "BUD/s" + C.GRAY + ": " + Form.f(engine.getBlockUpdatesPerSecond()));
             lines.add("&7&m                   ");
-                } else {
-                    lines.add("&7&m                   ");
-                    lines.add(C.GREEN + "Speed" + C.GRAY + ":  " + Form.f(engine.getGeneratedPerSecond(), 0) + "/s " + Form.duration(1000D / engine.getGeneratedPerSecond(), 0));
-                    lines.add(C.AQUA + "Cache" + C.GRAY + ": " + Form.f(IrisData.cacheSize()));
-                    lines.add(C.AQUA + "Mantle" + C.GRAY + ": " + engine.getMantle().getLoadedRegionCount());
-                    lines.add("&7&m                   ");
-                    lines.add(C.AQUA + "Region" + C.GRAY + ": " + engine.getRegion(x, z).getName());
-                    lines.add(C.AQUA + "Biome" + C.GRAY + ":  " + engine.getBiomeOrMantle(x, y, z).getName());
-                    lines.add(C.AQUA + "Height" + C.GRAY + ": " + Math.round(engine.getHeight(x, z)));
-                    lines.add(C.AQUA + "Slope" + C.GRAY + ":  " + Form.f(engine.getComplex().getSlopeStream().get(x, z), 2));
-                    lines.add(C.AQUA + "BUD/s" + C.GRAY + ": " + Form.f(engine.getBlockUpdatesPerSecond()));
-                    lines.add("&7&m                   ");
-                }
-            }
+            this.lines = lines;
         }
     }
 }

core/src/main/java/com/volmit/iris/core/service/CommandSVC.java

@@ -23,6 +23,7 @@ import com.volmit.iris.core.commands.CommandIris;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.decree.DecreeContext;
 import com.volmit.iris.util.decree.DecreeSystem;
 import com.volmit.iris.util.decree.virtual.VirtualDecreeCommand;
 import com.volmit.iris.util.format.C;
@@ -44,7 +45,14 @@ public class CommandSVC implements IrisService, DecreeSystem {
     @Override
     public void onEnable() {
         Iris.instance.getCommand("iris").setExecutor(this);
-        J.a(() -> getRoot().cacheAll());
+        J.a(() -> {
+            DecreeContext.touch(Iris.getSender());
+            try {
+                getRoot().cacheAll();
+            } finally {
+                DecreeContext.remove();
+            }
+        });
     }
 
     @Override

core/src/main/java/com/volmit/iris/core/service/StudioSVC.java

@@ -88,16 +88,18 @@ public class StudioSVC implements IrisService {
     }
 
     public IrisDimension installIntoWorld(VolmitSender sender, String type, File folder) {
+        return installInto(sender, type, new File(folder, "iris/pack"));
+    }
+
+    public IrisDimension installInto(VolmitSender sender, String type, File folder) {
         sender.sendMessage("Looking for Package: " + type);
-        File iris = new File(folder, "iris");
-        File irispack = new File(folder, "iris/pack");
-        IrisDimension dim = IrisData.loadAnyDimension(type);
+        IrisDimension dim = IrisData.loadAnyDimension(type, null);
 
         if (dim == null) {
             for (File i : getWorkspaceFolder().listFiles()) {
                 if (i.isFile() && i.getName().equals(type + ".iris")) {
                     sender.sendMessage("Found " + type + ".iris in " + WORKSPACE_NAME + " folder");
-                    ZipUtil.unpack(i, irispack);
+                    ZipUtil.unpack(i, folder);
                     break;
                 }
             }
@@ -106,29 +108,29 @@ public class StudioSVC implements IrisService {
             File f = new IrisProject(new File(getWorkspaceFolder(), type)).getPath();
 
             try {
-                FileUtils.copyDirectory(f, irispack);
+                FileUtils.copyDirectory(f, folder);
             } catch (IOException e) {
                 Iris.reportError(e);
             }
         }
 
-        File dimf = new File(irispack, "dimensions/" + type + ".json");
+        File dimensionFile = new File(folder, "dimensions/" + type + ".json");
 
-        if (!dimf.exists() || !dimf.isFile()) {
+        if (!dimensionFile.exists() || !dimensionFile.isFile()) {
             downloadSearch(sender, type, false);
             File downloaded = getWorkspaceFolder(type);
 
             for (File i : downloaded.listFiles()) {
                 if (i.isFile()) {
                     try {
-                        FileUtils.copyFile(i, new File(irispack, i.getName()));
+                        FileUtils.copyFile(i, new File(folder, i.getName()));
                     } catch (IOException e) {
                         e.printStackTrace();
                         Iris.reportError(e);
                     }
                 } else {
                     try {
-                        FileUtils.copyDirectory(i, new File(irispack, i.getName()));
+                        FileUtils.copyDirectory(i, new File(folder, i.getName()));
                     } catch (IOException e) {
                         e.printStackTrace();
                         Iris.reportError(e);
@@ -139,12 +141,13 @@ public class StudioSVC implements IrisService {
             IO.delete(downloaded);
         }
 
-        if (!dimf.exists() || !dimf.isFile()) {
-            sender.sendMessage("Can't find the " + dimf.getName() + " in the dimensions folder of this pack! Failed!");
+        if (!dimensionFile.exists() || !dimensionFile.isFile()) {
+            sender.sendMessage("Can't find the " + dimensionFile.getName() + " in the dimensions folder of this pack! Failed!");
             return null;
         }
 
-        IrisData dm = IrisData.get(irispack);
+        IrisData dm = IrisData.get(folder);
+        dm.hotloaded();
         dim = dm.getDimensionLoader().load(type);
 
         if (dim == null) {
@@ -261,6 +264,7 @@ public class StudioSVC implements IrisService {
         }
 
         IrisDimension d = data.getDimensionLoader().load(dimensions[0]);
+        data.close();
 
         if (d == null) {
             sender.sendMessage("Invalid dimension (folder) in dimensions folder");
@@ -275,7 +279,7 @@ public class StudioSVC implements IrisService {
             IO.delete(packEntry);
         }
 
-        if (IrisData.loadAnyDimension(key) != null) {
+        if (IrisData.loadAnyDimension(key, null) != null) {
             sender.sendMessage("Another dimension in the packs folder is already using the key " + key + " IMPORT FAILED!");
             return;
         }
@@ -294,6 +298,8 @@ public class StudioSVC implements IrisService {
             packEntry.mkdirs();
             ZipUtil.unpack(cp, packEntry);
         }
+        IrisData.getLoaded(packEntry)
+                .ifPresent(IrisData::hotloaded);
 
         sender.sendMessage("Successfully Aquired " + d.getName());
         ServerConfigurator.installDataPacks(true);

core/src/main/java/com/volmit/iris/core/tools/IrisCreator.java

@@ -135,12 +135,14 @@ public class IrisCreator {
                 .seed(seed)
                 .studio(studio)
                 .create();
-        ServerConfigurator.installDataPacks(false);
+        if (ServerConfigurator.installDataPacks(true)) {
+            throw new IrisException("Datapacks were missing!");
+        }
 
         PlatformChunkGenerator access = (PlatformChunkGenerator) wc.generator();
         if (access == null) throw new IrisException("Access is null. Something bad happened.");
 
-        AtomicBoolean failed = new AtomicBoolean(false);
+        AtomicBoolean done = new AtomicBoolean(false);
         J.a(() -> {
             IntSupplier g = () -> {
                 if (access.getEngine() == null) {
@@ -150,19 +152,13 @@ public class IrisCreator {
             };
             if(!benchmark) {
                 int req = access.getSpawnChunks().join();
-
-                while (g.getAsInt() < req) {
-                    if (failed.get()) {
-                        sender.sendMessage(C.RED + "Failed to create world!");
-                        return;
-                    }
-
-                    double v = (double) g.getAsInt() / (double) req;
+                for (int c = 0; c < req && !done.get(); c = g.getAsInt()) {
+                    double v = (double) c / req;
                     if (sender.isPlayer()) {
                         sender.sendProgress(v, "Generating");
                         J.sleep(16);
                     } else {
-                        sender.sendMessage(C.WHITE + "Generating " + Form.pc(v) + ((C.GRAY + " (" + (req - g.getAsInt()) + " Left)")));
+                        sender.sendMessage(C.WHITE + "Generating " + Form.pc(v) + ((C.GRAY + " (" + (req - c) + " Left)")));
                         J.sleep(1000);
                     }
                 }
@@ -176,10 +172,12 @@ public class IrisCreator {
                     .thenCompose(Function.identity())
                     .get();
         } catch (Throwable e) {
-            failed.set(true);
+            done.set(true);
             throw new IrisException("Failed to create world!", e);
         }
 
+        done.set(true);
+
         if (sender.isPlayer() && !benchmark) {
             Iris.platform.getChunkAtAsync(world, 0, 0, true, true)
                     .thenApply(Objects::requireNonNull)

core/src/main/java/com/volmit/iris/core/tools/IrisWorldCreator.java

@@ -64,7 +64,7 @@ public class IrisWorldCreator {
     }
 
     public WorldCreator create() {
-        IrisDimension dim = IrisData.loadAnyDimension(dimensionName);
+        IrisDimension dim = IrisData.loadAnyDimension(dimensionName, null);
 
         IrisWorld w = IrisWorld.builder()
                 .name(name)
@@ -80,13 +80,13 @@ public class IrisWorldCreator {
 
 
         return new WorldCreator(name)
-                .environment(findEnvironment())
+                .environment(w.environment())
                 .generateStructures(true)
                 .generator(g).seed(seed);
     }
 
     private World.Environment findEnvironment() {
-        IrisDimension dim = IrisData.loadAnyDimension(dimensionName);
+        IrisDimension dim = IrisData.loadAnyDimension(dimensionName, null);
         if (dim == null || dim.getEnvironment() == null) {
             return World.Environment.NORMAL;
         } else {

core/src/main/java/com/volmit/iris/engine/IrisWorldManager.java

@@ -20,7 +20,9 @@ package com.volmit.iris.engine;
 
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.core.service.ExternalDataSVC;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.framework.EngineAssignedWorldManager;
 import com.volmit.iris.engine.object.*;
@@ -426,18 +428,35 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
         }
 
         var ref = new WeakReference<>(e.getWorld());
-        int x = e.getX(), z = e.getZ();
+        int cX = e.getX(), cZ = e.getZ();
         J.s(() -> {
             World world = ref.get();
-            if (world == null || !world.isChunkLoaded(x, z))
+            if (world == null || !world.isChunkLoaded(cX, cZ))
                 return;
             energy += 0.3;
             fixEnergy();
-            getEngine().cleanupMantleChunk(x, z);
+            getEngine().cleanupMantleChunk(cX, cZ);
         }, IrisSettings.get().getPerformance().mantleCleanupDelay);
 
         if (generated) {
             //INMS.get().injectBiomesFromMantle(e, getMantle());
+
+            if (!IrisSettings.get().getGenerator().earlyCustomBlocks) return;
+            e.addPluginChunkTicket(Iris.instance);
+            J.s(() -> {
+                var chunk = getMantle().getChunk(e).use();
+                int minY = getTarget().getWorld().minHeight();
+                try {
+                    chunk.raiseFlagUnchecked(MantleFlag.CUSTOM, () -> {
+                        chunk.iterate(Identifier.class, (x, y, z, v) -> {
+                            Iris.service(ExternalDataSVC.class).processUpdate(getEngine(), e.getBlock(x & 15, y + minY, z & 15), v);
+                        });
+                    });
+                } finally {
+                    chunk.release();
+                    e.removePluginChunkTicket(Iris.instance);
+                }
+            }, RNG.r.i(20, 60));
         }
     }
 

core/src/main/java/com/volmit/iris/engine/framework/Engine.java

@@ -295,20 +295,20 @@ public interface Engine extends DataProvider, Fallible, LootProvider, BlockUpdat
         try {
             Semaphore semaphore = new Semaphore(3);
             chunk.raiseFlag(MantleFlag.ETCHED, () -> {
-                chunk.raiseFlag(MantleFlag.TILE, run(semaphore, () -> {
+                chunk.raiseFlagUnchecked(MantleFlag.TILE, run(semaphore, () -> {
                     chunk.iterate(TileWrapper.class, (x, y, z, v) -> {
                         Block block = c.getBlock(x & 15, y + getWorld().minHeight(), z & 15);
                         if (!TileData.setTileState(block, v.getData()))
                             Iris.warn("Failed to set tile entity data at [%d %d %d | %s] for tile %s!", block.getX(), block.getY(), block.getZ(), block.getType().getKey(), v.getData().getMaterial().getKey());
                     });
                 }, c, 1));
-                chunk.raiseFlag(MantleFlag.CUSTOM, run(semaphore, () -> {
+                chunk.raiseFlagUnchecked(MantleFlag.CUSTOM, run(semaphore, () -> {
                     chunk.iterate(Identifier.class, (x, y, z, v) -> {
                         Iris.service(ExternalDataSVC.class).processUpdate(this, c.getBlock(x & 15, y + getWorld().minHeight(), z & 15), v);
                     });
                 }, c, 1));
 
-                chunk.raiseFlag(MantleFlag.UPDATE, run(semaphore, () -> {
+                chunk.raiseFlagUnchecked(MantleFlag.UPDATE, run(semaphore, () -> {
                     PrecisionStopwatch p = PrecisionStopwatch.start();
                     int[][] grid = new int[16][16];
                     for (int x = 0; x < 16; x++) {
@@ -863,7 +863,7 @@ public interface Engine extends DataProvider, Fallible, LootProvider, BlockUpdat
     default void gotoBiome(IrisBiome biome, Player player, boolean teleport) {
         Set<String> regionKeys = getDimension()
                 .getAllRegions(this).stream()
-                .filter((i) -> i.getAllBiomes(this).contains(biome))
+                .filter((i) -> i.getAllBiomeIds().contains(biome.getLoadKey()))
                 .map(IrisRegistrant::getLoadKey)
                 .collect(Collectors.toSet());
         Locator<IrisBiome> lb = Locator.surfaceBiome(biome.getLoadKey());
@@ -959,7 +959,7 @@ public interface Engine extends DataProvider, Fallible, LootProvider, BlockUpdat
     }
 
     default void gotoRegion(IrisRegion r, Player player, boolean teleport) {
-        if (!getDimension().getAllRegions(this).contains(r)) {
+        if (!getDimension().getRegions().contains(r.getLoadKey())) {
             player.sendMessage(C.RED + r.getName() + " is not defined in the dimension!");
             return;
         }

core/src/main/java/com/volmit/iris/engine/mantle/components/MantleJigsawComponent.java

@@ -167,6 +167,7 @@ public class MantleJigsawComponent extends IrisMantleComponent {
 
     @BlockCoordinates
     private boolean place(MantleWriter writer, IrisPosition position, IrisJigsawStructure structure, RNG rng, boolean forcePlace) {
+        if (structure == null || structure.getDatapackStructures().isNotEmpty()) return false;
         return new PlannedStructure(structure, position, rng, forcePlace).place(writer, getMantle(), writer.getEngine());
     }
 

core/src/main/java/com/volmit/iris/engine/modifier/IrisPostModifier.java

@@ -21,6 +21,7 @@ package com.volmit.iris.engine.modifier;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.framework.EngineAssignedModifier;
 import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisSlopeClip;
 import com.volmit.iris.util.context.ChunkContext;
 import com.volmit.iris.util.data.B;
 import com.volmit.iris.util.hunk.Hunk;
@@ -174,7 +175,8 @@ public class IrisPostModifier extends EngineAssignedModifier<BlockData> {
                     || (hd == h + 1 && isSolidNonSlab(x, hd, z - 1, currentPostX, currentPostZ, currentData)))
             //@done
             {
-                BlockData d = biome.getSlab().get(rng, x, h, z, getData());
+                IrisSlopeClip sc = biome.getSlab().getSlopeCondition();
+                BlockData d = sc.isValid(getComplex().getSlopeStream().get(x, z)) ? biome.getSlab().get(rng, x, h, z, getData()) : null;
 
                 if (d != null) {
                     boolean cancel = B.isAir(d);

core/src/main/java/com/volmit/iris/engine/object/IrisDimension.java

@@ -355,7 +355,7 @@ public class IrisDimension extends IrisRegistrant {
         KList<IrisRegion> r = new KList<>();
 
         for (String i : getRegions()) {
-            r.add(IrisData.loadAnyRegion(i));
+            r.add(IrisData.loadAnyRegion(i, getLoader()));
         }
 
         return r;

core/src/main/java/com/volmit/iris/engine/object/IrisJigsawStructure.java

@@ -23,6 +23,7 @@ import com.volmit.iris.core.loader.IrisRegistrant;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.object.annotations.*;
 import com.volmit.iris.engine.object.annotations.functions.StructureKeyFunction;
+import com.volmit.iris.engine.object.annotations.functions.StructureKeyOrTagFunction;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.json.JSONObject;
 import com.volmit.iris.util.plugin.VolmitSender;
@@ -40,6 +41,11 @@ import lombok.experimental.Accessors;
 @Data
 @EqualsAndHashCode(callSuper = false)
 public class IrisJigsawStructure extends IrisRegistrant {
+    @RegistryListFunction(StructureKeyFunction.class)
+    @ArrayType(min = 1, type = String.class)
+    @Desc("The datapack structures. Randomply chooses a structure to place\nIgnores every other setting")
+    private KList<String> datapackStructures = new KList<>();
+
     @RegistryListResource(IrisJigsawPiece.class)
     @Required
     @ArrayType(min = 1, type = String.class)
@@ -70,7 +76,7 @@ public class IrisJigsawStructure extends IrisRegistrant {
     @Desc("Set to true to prevent rotating the initial structure piece")
     private boolean disableInitialRotation = false;
 
-    @RegistryListFunction(StructureKeyFunction.class)
+    @RegistryListFunction(StructureKeyOrTagFunction.class)
     @Desc("The minecraft key to use when creating treasure maps")
     private String structureKey = null;
 
@@ -117,6 +123,10 @@ public class IrisJigsawStructure extends IrisRegistrant {
 
     public int getMaxDimension() {
         return maxDimension.aquire(() -> {
+            if (datapackStructures.isNotEmpty()) {
+                return 0;
+            }
+
             if (useMaxPieceSizeForParallaxRadius) {
                 int max = 0;
                 KList<String> pools = new KList<>();

core/src/main/java/com/volmit/iris/engine/object/IrisRegion.java

@@ -346,7 +346,7 @@ public class IrisRegion extends IrisRegistrant implements IRare {
                     continue;
                 }
 
-                IrisBiome biome = IrisData.loadAnyBiome(i);
+                IrisBiome biome = IrisData.loadAnyBiome(i, getLoader());
 
                 names.remove(i);
                 if (biome == null) {

core/src/main/java/com/volmit/iris/engine/object/IrisStructurePopulator.java

@@ -0,0 +1,74 @@
+package com.volmit.iris.engine.object;
+
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.framework.EngineAssignedComponent;
+import com.volmit.iris.util.collection.KList;
+import com.volmit.iris.util.documentation.ChunkCoordinates;
+import com.volmit.iris.util.math.Position2;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.noise.CNG;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+import java.util.function.BiPredicate;
+
+public class IrisStructurePopulator extends EngineAssignedComponent {
+    private final CNG cng;
+    private final long mantle;
+    private final long jigsaw;
+
+    public IrisStructurePopulator(Engine engine) {
+        super(engine, "Datapack Structures");
+        mantle = engine.getSeedManager().getMantle();
+        jigsaw = engine.getSeedManager().getJigsaw();
+        cng = NoiseStyle.STATIC.create(new RNG(jigsaw));
+    }
+
+    @ChunkCoordinates
+    public void populateStructures(int x, int z, BiPredicate<String, Boolean> placer) {
+        int bX = x << 4, bZ = z << 4;
+        var dimension = getDimension();
+        var region = getEngine().getRegion(bX + 8, bZ + 8);
+        var biome = getEngine().getSurfaceBiome(bX + 8, bZ + 8);
+        var loader = getData().getJigsawStructureLoader();
+
+        long seed = cng.fit(Integer.MIN_VALUE, Integer.MAX_VALUE, x, z);
+        if (dimension.getStronghold() != null) {
+            var list = getDimension().getStrongholds(mantle);
+            if (list != null && list.contains(new Position2(bX, bZ))) {
+                place(placer, loader.load(dimension.getStronghold()), new RNG(seed), true);
+                return;
+            }
+        }
+
+        boolean placed = place(placer, biome.getJigsawStructures(), seed, x, z);
+        if (!placed) placed = place(placer, region.getJigsawStructures(), seed, x, z);
+        if (!placed) place(placer, dimension.getJigsawStructures(), seed, x, z);
+    }
+
+    private boolean place(BiPredicate<String, Boolean> placer, KList<IrisJigsawStructurePlacement> placements, long seed, int x, int z) {
+        var placement = pick(placements, seed, x, z);
+        if (placement == null) return false;
+        return place(placer, getData().getJigsawStructureLoader().load(placement.getStructure()), new RNG(seed), false);
+    }
+
+    @Nullable
+    @ChunkCoordinates
+    private IrisJigsawStructurePlacement pick(List<IrisJigsawStructurePlacement> structures, long seed, int x, int z) {
+        return IRare.pick(structures.stream()
+                .filter(p -> p.shouldPlace(getData(), getDimension().getJigsawStructureDivisor(), jigsaw, x, z))
+                .toList(), new RNG(seed).nextDouble());
+    }
+
+    @ChunkCoordinates
+    private boolean place(BiPredicate<String, Boolean> placer, IrisJigsawStructure structure, RNG rng, boolean ignoreBiomes) {
+        if (structure == null || structure.getDatapackStructures().isEmpty()) return false;
+        var keys = structure.getDatapackStructures().shuffleCopy(rng);
+        while (keys.isNotEmpty()) {
+            String key = keys.removeFirst();
+            if (key != null && placer.test(key, ignoreBiomes || structure.isForcePlace()))
+                return true;
+        }
+        return false;
+    }
+}

core/src/main/java/com/volmit/iris/engine/object/annotations/functions/StructureKeyFunction.java

@@ -18,6 +18,6 @@ public class StructureKeyFunction implements ListFunction<KList<String>> {
 
     @Override
     public KList<String> apply(IrisData irisData) {
-        return INMS.get().getStructureKeys();
+        return INMS.get().getStructureKeys().removeWhere(t -> t.startsWith("#"));
     }
 }

core/src/main/java/com/volmit/iris/engine/object/annotations/functions/StructureKeyOrTagFunction.java

@@ -0,0 +1,23 @@
+package com.volmit.iris.engine.object.annotations.functions;
+
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.core.nms.INMS;
+import com.volmit.iris.engine.framework.ListFunction;
+import com.volmit.iris.util.collection.KList;
+
+public class StructureKeyOrTagFunction implements ListFunction<KList<String>> {
+    @Override
+    public String key() {
+        return "structure-key-or-tag";
+    }
+
+    @Override
+    public String fancyName() {
+        return "Structure Key or Tag";
+    }
+
+    @Override
+    public KList<String> apply(IrisData irisData) {
+        return INMS.get().getStructureKeys();
+    }
+}

core/src/main/java/com/volmit/iris/engine/platform/BukkitChunkGenerator.java

@@ -169,15 +169,12 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
 
             if (dimension == null) {
                 Iris.error("Oh No! There's no pack in " + data.getDataFolder().getPath() + " or... there's no dimension for the key " + dimensionKey);
-                IrisDimension test = IrisData.loadAnyDimension(dimensionKey);
+                IrisDimension test = IrisData.loadAnyDimension(dimensionKey, null);
 
                 if (test != null) {
                     Iris.warn("Looks like " + dimensionKey + " exists in " + test.getLoadFile().getPath() + " ");
-                    Iris.service(StudioSVC.class).installIntoWorld(Iris.getSender(), dimensionKey, dataLocation.getParentFile().getParentFile());
+                    test = Iris.service(StudioSVC.class).installInto(Iris.getSender(), dimensionKey, dataLocation);
                     Iris.warn("Attempted to install into " + data.getDataFolder().getPath());
-                    data.dump();
-                    data.clearLists();
-                    test = data.getDimensionLoader().load(dimensionKey);
 
                     if (test != null) {
                         Iris.success("Woo! Patched the Engine!");
@@ -240,11 +237,12 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
                     }
                 }, syncExecutor));
             }
+            futures.add(CompletableFuture.runAsync(() -> INMS.get().placeStructures(c), syncExecutor));
 
             CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]))
                     .thenRunAsync(() -> {
                         c.removePluginChunkTicket(Iris.instance);
-                        c.unload();
+                        engine.getWorldManager().onChunkLoad(c, true);
                     }, syncExecutor)
                     .get();
             Iris.debug("Regenerated " + x + " " + z);
@@ -356,16 +354,16 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
     @Override
     public void generateNoise(@NotNull WorldInfo world, @NotNull Random random, int x, int z, @NotNull ChunkGenerator.ChunkData d) {
         try {
-            getEngine(world);
+            Engine engine = getEngine(world);
             computeStudioGenerator();
             TerrainChunk tc = TerrainChunk.create(d, new IrisBiomeStorage());
             this.world.bind(world);
             if (studioGenerator != null) {
-                studioGenerator.generateChunk(getEngine(), tc, x, z);
+                studioGenerator.generateChunk(engine, tc, x, z);
             } else {
                 ChunkDataHunkHolder blocks = new ChunkDataHunkHolder(tc);
                 BiomeGridHunkHolder biomes = new BiomeGridHunkHolder(tc, tc.getMinHeight(), tc.getMaxHeight());
-                getEngine().generate(x << 4, z << 4, blocks, biomes, IrisSettings.get().getGenerator().useMulticore);
+                engine.generate(x << 4, z << 4, blocks, biomes, IrisSettings.get().getGenerator().useMulticore);
                 blocks.apply();
                 biomes.apply();
             }

core/src/main/java/com/volmit/iris/util/board/Board.java

@@ -23,15 +23,11 @@ import lombok.NonNull;
 import lombok.Setter;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
-import org.bukkit.scoreboard.DisplaySlot;
-import org.bukkit.scoreboard.Objective;
-import org.bukkit.scoreboard.Scoreboard;
-import org.bukkit.scoreboard.Team;
+import org.bukkit.scoreboard.*;
 
 import java.util.Collections;
 import java.util.List;
-import java.util.function.Function;
-import java.util.stream.Collectors;
+import java.util.function.UnaryOperator;
 import java.util.stream.IntStream;
 
 /**
@@ -42,7 +38,7 @@ public class Board {
 
     private static final String[] CACHED_ENTRIES = new String[C.values().length];
 
-    private static final Function<String, String> APPLY_COLOR_TRANSLATION = s -> C.translateAlternateColorCodes('&', s);
+    private static final UnaryOperator<String> APPLY_COLOR_TRANSLATION = s -> C.translateAlternateColorCodes('&', s);
 
     static {
         IntStream.range(0, 15).forEach(i -> CACHED_ENTRIES[i] = C.values()[i].toString() + C.RESET);
@@ -54,13 +50,14 @@ public class Board {
     private BoardSettings boardSettings;
     private boolean ready;
 
-    @SuppressWarnings("deprecation")
     public Board(@NonNull final Player player, final BoardSettings boardSettings) {
         this.player = player;
         this.boardSettings = boardSettings;
-        this.objective = this.getScoreboard().getObjective("board") == null ? this.getScoreboard().registerNewObjective("board", "dummy") : this.getScoreboard().getObjective("board");
+        var obj = getScoreboard().getObjective("board");
+        this.objective = obj == null ? this.getScoreboard().registerNewObjective("board", Criteria.DUMMY, "Iris") : obj;
         this.objective.setDisplaySlot(DisplaySlot.SIDEBAR);
-        Team team = this.getScoreboard().getTeam("board") == null ? this.getScoreboard().registerNewTeam("board") : this.getScoreboard().getTeam("board");
+        Team team = getScoreboard().getTeam("board");
+        team = team == null ? getScoreboard().registerNewTeam("board") : team;
         team.setAllowFriendlyFire(true);
         team.setCanSeeFriendlyInvisibles(false);
         team.setPrefix("");
@@ -94,7 +91,8 @@ public class Board {
         }
 
         // Getting their Scoreboard display from the Scoreboard Provider.
-        final List<String> entries = boardSettings.getBoardProvider().getLines(player).stream().map(APPLY_COLOR_TRANSLATION).collect(Collectors.toList());
+        final List<String> entries = boardSettings.getBoardProvider().getLines(player);
+        entries.replaceAll(APPLY_COLOR_TRANSLATION);
 
         if (boardSettings.getScoreDirection() == ScoreDirection.UP) {
             Collections.reverse(entries);

core/src/main/java/com/volmit/iris/util/board/BoardUpdateTask.java

@@ -37,6 +37,12 @@ public class BoardUpdateTask implements Runnable {
 
     @Override
     public void run() {
-        boardManager.getScoreboards().entrySet().stream().filter(entrySet -> PLAYER_IS_ONLINE.test(entrySet.getKey())).forEach(entrySet -> entrySet.getValue().update());
+        for (var entry : boardManager.getScoreboards().entrySet()) {
+            if (!PLAYER_IS_ONLINE.test(entry.getKey())) {
+                continue;
+            }
+
+            entry.getValue().update();
+        }
     }
 }

core/src/main/java/com/volmit/iris/util/collection/KSet.java

@@ -22,6 +22,7 @@ import org.jetbrains.annotations.NotNull;
 
 import java.io.Serializable;
 import java.util.AbstractSet;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.concurrent.ConcurrentHashMap;
@@ -30,13 +31,15 @@ public class KSet<T> extends AbstractSet<T> implements Serializable {
     private static final long serialVersionUID = 1L;
     private final ConcurrentHashMap<T, Boolean> map;
 
-    public KSet() {
-        map = new ConcurrentHashMap<>();
+    public KSet(Collection<? extends T> c) {
+        this(c.size());
+        addAll(c);
     }
 
-    public KSet(Collection<? extends T> c) {
-        this();
-        addAll(c);
+    @SafeVarargs
+    public KSet(T... values) {
+        this(values.length);
+        addAll(Arrays.asList(values));
     }
 
     public KSet(int initialCapacity, float loadFactor) {
@@ -47,6 +50,13 @@ public class KSet<T> extends AbstractSet<T> implements Serializable {
         map = new ConcurrentHashMap<>(initialCapacity);
     }
 
+    public static <T> KSet<T> merge(Collection<? extends T> first, Collection<? extends T> second) {
+        var set = new KSet<T>();
+        set.addAll(first);
+        set.addAll(second);
+        return set;
+    }
+
     @Override
     public int size() {
         return map.size();

core/src/main/java/com/volmit/iris/util/data/B.java

@@ -498,7 +498,7 @@ public class B {
             if (!ix.startsWith("minecraft:") && ix.contains(":")) {
                 Identifier key = Identifier.fromString(ix);
                 Optional<BlockData> bd = Iris.service(ExternalDataSVC.class).getBlockData(key);
-                Iris.info("Loading block data " + key);
+                Iris.debug("Loading block data " + key);
                 if (bd.isPresent())
                     bx = bd.get();
             }

core/src/main/java/com/volmit/iris/util/decree/DecreeContext.java

@@ -18,29 +18,20 @@
 
 package com.volmit.iris.util.decree;
 
-import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.plugin.VolmitSender;
-import com.volmit.iris.util.scheduling.ChronoLatch;
 
 public class DecreeContext {
-    private static final ChronoLatch cl = new ChronoLatch(60000);
-    private static final KMap<Thread, VolmitSender> context = new KMap<>();
+    private static final ThreadLocal<VolmitSender> context = new ThreadLocal<>();
 
     public static VolmitSender get() {
-        return context.get(Thread.currentThread());
+        return context.get();
     }
 
     public static void touch(VolmitSender c) {
-        synchronized (context) {
-            context.put(Thread.currentThread(), c);
+        context.set(c);
+    }
 
-            if (cl.flip()) {
-                for (Thread i : context.k()) {
-                    if (!i.isAlive()) {
-                        context.remove(i);
-                    }
-                }
-            }
-        }
+    public static void remove() {
+        context.remove();
     }
 }

core/src/main/java/com/volmit/iris/util/decree/DecreeExecutor.java

@@ -18,6 +18,7 @@
 
 package com.volmit.iris.util.decree;
 
+import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
@@ -34,6 +35,14 @@ public interface DecreeExecutor {
         return sender().player();
     }
 
+    default IrisData data() {
+        var access = access();
+        if (access != null) {
+            return access.getData();
+        }
+        return null;
+    }
+
     default Engine engine() {
         if (sender().isPlayer() && IrisToolbelt.access(sender().player().getWorld()) != null) {
             PlatformChunkGenerator gen = IrisToolbelt.access(sender().player().getWorld());

core/src/main/java/com/volmit/iris/util/decree/DecreeParameterHandler.java

@@ -23,7 +23,7 @@ import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
 
 import java.util.concurrent.atomic.AtomicReference;
 
-public interface DecreeParameterHandler<T> {
+public interface DecreeParameterHandler<T> extends DecreeExecutor {
     /**
      * Should return the possible values for this type
      *

core/src/main/java/com/volmit/iris/util/decree/DecreeSystem.java

@@ -133,12 +133,18 @@ public interface DecreeSystem extends CommandExecutor, TabCompleter {
 
     default boolean call(VolmitSender sender, String[] args) {
         DecreeContext.touch(sender);
+        try {
             return getRoot().invoke(sender, enhanceArgs(args));
+        } finally {
+            DecreeContext.remove();
+        }
     }
 
     @Nullable
     @Override
     default List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String alias, @NotNull String[] args) {
+        DecreeContext.touch(new VolmitSender(sender));
+        try {
             KList<String> enhanced = new KList<>(args);
             KList<String> v = getRoot().tabComplete(enhanced, enhanced.toString(" "));
             v.removeDuplicates();
@@ -150,6 +156,9 @@ public interface DecreeSystem extends CommandExecutor, TabCompleter {
             }
 
             return v;
+        } finally {
+            DecreeContext.remove();
+        }
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/BiomeHandler.java

@@ -18,63 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisBiome;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class BiomeHandler implements DecreeParameterHandler<IrisBiome> {
-    @Override
-    public KList<IrisBiome> getPossibilities() {
-        KMap<String, IrisBiome> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisBiome j : data.getBiomeLoader().loadAll(data.getBiomeLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisBiome dim) {
-        return dim.getLoadKey();
-    }
-
-    @Override
-    public IrisBiome parse(String in, boolean force) throws DecreeParsingException {
-        if (in.equals("null")) {
-            return null;
-        }
-        KList<IrisBiome> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Biome \"" + in + "\"");
-        }
-
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Biome \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisBiome.class);
+public class BiomeHandler extends RegistrantHandler<IrisBiome> {
+    public BiomeHandler() {
+        super(IrisBiome.class, true);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/CaveHandler.java

@@ -18,62 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisCave;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class CaveHandler implements DecreeParameterHandler<IrisCave> {
-    @Override
-    public KList<IrisCave> getPossibilities() {
-        KMap<String, IrisCave> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisCave j : data.getCaveLoader().loadAll(data.getCaveLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisCave dim) {
-        return dim.getLoadKey();
-    }
-
-    @Override
-    public IrisCave parse(String in, boolean force) throws DecreeParsingException {
-        if (in.equals("null")) {
-            return null;
-        }
-        KList<IrisCave> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Cave \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Cave\"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisCave.class);
+public class CaveHandler extends RegistrantHandler<IrisCave> {
+    public CaveHandler() {
+        super(IrisCave.class, true);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/DimensionHandler.java

@@ -18,65 +18,22 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
 import com.volmit.iris.core.IrisSettings;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisDimension;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
 import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-
-public class DimensionHandler implements DecreeParameterHandler<IrisDimension> {
-    @Override
-    public KList<IrisDimension> getPossibilities() {
-        KMap<String, IrisDimension> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisDimension j : data.getDimensionLoader().loadAll(data.getDimensionLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisDimension dim) {
-        return dim.getLoadKey();
+public class DimensionHandler extends RegistrantHandler<IrisDimension> {
+    public DimensionHandler() {
+        super(IrisDimension.class, false);
     }
 
     @Override
     public IrisDimension parse(String in, boolean force) throws DecreeParsingException {
-
         if (in.equalsIgnoreCase("default")) {
             return parse(IrisSettings.get().getGenerator().getDefaultWorldType());
         }
-
-        KList<IrisDimension> options = getPossibilities(in);
-
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Dimension \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).toList().get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Dimension \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisDimension.class);
+        return super.parse(in, force);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/EntityHandler.java

@@ -18,84 +18,13 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisEntity;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
+public class EntityHandler extends RegistrantHandler<IrisEntity> {
 
-public class EntityHandler implements DecreeParameterHandler<IrisEntity> {
-
-    /**
-     * Should return the possible values for this type
-     *
-     * @return Possibilities for this type.
-     */
-    @Override
-    public KList<IrisEntity> getPossibilities() {
-        KMap<String, IrisEntity> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisEntity j : data.getEntityLoader().loadAll(data.getEntityLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    /**
-     * Converting the type back to a string (inverse of the {@link #parse(String) parse} method)
-     *
-     * @param entity The input of the designated type to convert to a String
-     * @return The resulting string
-     */
-    @Override
-    public String toString(IrisEntity entity) {
-        return entity.getLoadKey();
-    }
-
-    /**
-     * Should parse a String into the designated type
-     *
-     * @param in The string to parse
-     * @return The value extracted from the string, of the designated type
-     * @throws DecreeParsingException Thrown when the parsing fails (ex: "oop" translated to an integer throws this)
-     */
-    @Override
-    public IrisEntity parse(String in, boolean force) throws DecreeParsingException {
-        KList<IrisEntity> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Entity \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Entity \"" + in + "\"");
-        }
-    }
-
-    /**
-     * Returns whether a certain type is supported by this handler<br>
-     *
-     * @param type The type to check
-     * @return True if supported, false if not
-     */
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisEntity.class);
+    public EntityHandler() {
+        super(IrisEntity.class, false);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/GeneratorHandler.java

@@ -18,59 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisGenerator;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class GeneratorHandler implements DecreeParameterHandler<IrisGenerator> {
-    @Override
-    public KList<IrisGenerator> getPossibilities() {
-        KMap<String, IrisGenerator> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisGenerator j : data.getGeneratorLoader().loadAll(data.getGeneratorLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisGenerator gen) {
-        return gen.getLoadKey();
-    }
-
-    @Override
-    public IrisGenerator parse(String in, boolean force) throws DecreeParsingException {
-        KList<IrisGenerator> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Generator \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Generator \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisGenerator.class);
+public class GeneratorHandler extends RegistrantHandler<IrisGenerator> {
+    public GeneratorHandler() {
+        super(IrisGenerator.class, false);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/JigsawPieceHandler.java

@@ -18,62 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisJigsawPiece;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class JigsawPieceHandler implements DecreeParameterHandler<IrisJigsawPiece> {
-    @Override
-    public KList<IrisJigsawPiece> getPossibilities() {
-        KMap<String, IrisJigsawPiece> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisJigsawPiece j : data.getJigsawPieceLoader().loadAll(data.getJigsawPieceLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisJigsawPiece dim) {
-        return dim.getLoadKey();
-    }
-
-    @Override
-    public IrisJigsawPiece parse(String in, boolean force) throws DecreeParsingException {
-        if (in.equals("null")) {
-            return null;
-        }
-        KList<IrisJigsawPiece> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Jigsaw Piece \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Jigsaw Piece \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisJigsawPiece.class);
+public class JigsawPieceHandler extends RegistrantHandler<IrisJigsawPiece> {
+    public JigsawPieceHandler() {
+        super(IrisJigsawPiece.class, true);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/JigsawPoolHandler.java

@@ -18,62 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisJigsawPool;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class JigsawPoolHandler implements DecreeParameterHandler<IrisJigsawPool> {
-    @Override
-    public KList<IrisJigsawPool> getPossibilities() {
-        KMap<String, IrisJigsawPool> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisJigsawPool j : data.getJigsawPoolLoader().loadAll(data.getJigsawPoolLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisJigsawPool dim) {
-        return dim.getLoadKey();
-    }
-
-    @Override
-    public IrisJigsawPool parse(String in, boolean force) throws DecreeParsingException {
-        if (in.equals("null")) {
-            return null;
-        }
-        KList<IrisJigsawPool> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Jigsaw Pool \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Jigsaw Pool \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisJigsawPool.class);
+public class JigsawPoolHandler extends RegistrantHandler<IrisJigsawPool> {
+    public JigsawPoolHandler() {
+        super(IrisJigsawPool.class, true);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/JigsawStructureHandler.java

@@ -18,62 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class JigsawStructureHandler implements DecreeParameterHandler<IrisJigsawStructure> {
-    @Override
-    public KList<IrisJigsawStructure> getPossibilities() {
-        KMap<String, IrisJigsawStructure> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisJigsawStructure j : data.getJigsawStructureLoader().loadAll(data.getJigsawStructureLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisJigsawStructure dim) {
-        return dim.getLoadKey();
-    }
-
-    @Override
-    public IrisJigsawStructure parse(String in, boolean force) throws DecreeParsingException {
-        if (in.equals("null")) {
-            return null;
-        }
-        KList<IrisJigsawStructure> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Jigsaw Structure \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Jigsaw Structure \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisJigsawStructure.class);
+public class JigsawStructureHandler extends RegistrantHandler<IrisJigsawStructure> {
+    public JigsawStructureHandler() {
+        super(IrisJigsawStructure.class, true);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/RegionHandler.java

@@ -18,62 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisRegion;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class RegionHandler implements DecreeParameterHandler<IrisRegion> {
-    @Override
-    public KList<IrisRegion> getPossibilities() {
-        KMap<String, IrisRegion> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisRegion j : data.getRegionLoader().loadAll(data.getRegionLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisRegion dim) {
-        return dim.getLoadKey();
-    }
-
-    @Override
-    public IrisRegion parse(String in, boolean force) throws DecreeParsingException {
-        if (in.equals("null")) {
-            return null;
-        }
-        KList<IrisRegion> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Region \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Region \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisRegion.class);
+public class RegionHandler extends RegistrantHandler<IrisRegion> {
+    public RegionHandler() {
+        super(IrisRegion.class, true);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/handlers/ScriptHandler.java

@@ -18,59 +18,12 @@
 
 package com.volmit.iris.util.decree.handlers;
 
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.engine.object.IrisScript;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.decree.DecreeParameterHandler;
-import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+import com.volmit.iris.util.decree.specialhandlers.RegistrantHandler;
 
-import java.io.File;
-import java.util.stream.Collectors;
-
-public class ScriptHandler implements DecreeParameterHandler<IrisScript> {
-    @Override
-    public KList<IrisScript> getPossibilities() {
-        KMap<String, IrisScript> p = new KMap<>();
-
-        //noinspection ConstantConditions
-        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
-            if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
-                for (IrisScript j : data.getScriptLoader().loadAll(data.getScriptLoader().getPossibleKeys())) {
-                    p.putIfAbsent(j.getLoadKey(), j);
-                }
-
-                data.close();
-            }
-        }
-
-        return p.v();
-    }
-
-    @Override
-    public String toString(IrisScript script) {
-        return script.getLoadKey();
-    }
-
-    @Override
-    public IrisScript parse(String in, boolean force) throws DecreeParsingException {
-        KList<IrisScript> options = getPossibilities(in);
-
-        if (options.isEmpty()) {
-            throw new DecreeParsingException("Unable to find Script \"" + in + "\"");
-        }
-        try {
-            return options.stream().filter((i) -> toString(i).equalsIgnoreCase(in)).collect(Collectors.toList()).get(0);
-        } catch (Throwable e) {
-            throw new DecreeParsingException("Unable to filter which Script \"" + in + "\"");
-        }
-    }
-
-    @Override
-    public boolean supports(Class<?> type) {
-        return type.equals(IrisScript.class);
+public class ScriptHandler extends RegistrantHandler<IrisScript> {
+    public ScriptHandler() {
+        super(IrisScript.class, false);
     }
 
     @Override

core/src/main/java/com/volmit/iris/util/decree/specialhandlers/NullableDimensionHandler.java

@@ -16,28 +16,27 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.volmit.iris.engine.object;
+package com.volmit.iris.util.decree.specialhandlers;
 
-import com.volmit.iris.engine.object.annotations.*;
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import lombok.experimental.Accessors;
+import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.engine.object.IrisDimension;
+import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
 
-@Snippet("jigsaw-placer")
-@Accessors(chain = true)
-@NoArgsConstructor
-@AllArgsConstructor
-@Desc("Represents a jigsaw placement")
-@Data
-public class IrisJigsawPlacement {
-    @RegistryListResource(IrisJigsawStructure.class)
-    @Required
-    @Desc("The jigsaw structure to use")
-    private String structure = "";
-
-    @Required
-    @MinNumber(1)
-    @Desc("The rarity for this jigsaw structure to place on a per chunk basis")
-    private int rarity = 29;
+public class NullableDimensionHandler extends RegistrantHandler<IrisDimension> {
+    public NullableDimensionHandler() {
+        super(IrisDimension.class, true);
+    }
+
+    @Override
+    public IrisDimension parse(String in, boolean force) throws DecreeParsingException {
+        if (in.equalsIgnoreCase("default")) {
+            return parse(IrisSettings.get().getGenerator().getDefaultWorldType());
+        }
+        return super.parse(in, force);
+    }
+
+    @Override
+    public String getRandomDefault() {
+        return "dimension";
+    }
 }

core/src/main/java/com/volmit/iris/util/decree/specialhandlers/ObjectHandler.java

@@ -31,11 +31,15 @@ public class ObjectHandler implements DecreeParameterHandler<String> {
     @Override
     public KList<String> getPossibilities() {
         KList<String> p = new KList<>();
+        IrisData data = data();
+        if (data != null) {
+            return new KList<>(data.getObjectLoader().getPossibleKeys());
+        }
 
         //noinspection ConstantConditions
         for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
             if (i.isDirectory()) {
-                IrisData data = IrisData.get(i);
+                data = IrisData.get(i);
                 p.add(data.getObjectLoader().getPossibleKeys());
             }
         }

core/src/main/java/com/volmit/iris/util/decree/specialhandlers/RegistrantHandler.java

@@ -0,0 +1,76 @@
+package com.volmit.iris.util.decree.specialhandlers;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.core.loader.IrisRegistrant;
+import com.volmit.iris.util.collection.KList;
+import com.volmit.iris.util.decree.DecreeParameterHandler;
+import com.volmit.iris.util.decree.exceptions.DecreeParsingException;
+
+import java.io.File;
+import java.util.HashSet;
+import java.util.Set;
+
+public abstract class RegistrantHandler<T extends IrisRegistrant> implements DecreeParameterHandler<T> {
+    private final Class<T> type;
+    private final String name;
+    private final boolean nullable;
+
+    public RegistrantHandler(Class<T> type, boolean nullable) {
+        this.type = type;
+        this.name = type.getSimpleName().replaceFirst("Iris", "");
+        this.nullable = nullable;
+    }
+
+    @Override
+    public KList<T> getPossibilities() {
+        KList<T> p = new KList<>();
+        Set<String> known = new HashSet<>();
+        IrisData data = data();
+        if (data != null) {
+            for (T j : data.getLoader(type).loadAll(data.getLoader(type).getPossibleKeys())) {
+                known.add(j.getLoadKey());
+                p.add(j);
+            }
+        }
+
+        //noinspection ConstantConditions
+        for (File i : Iris.instance.getDataFolder("packs").listFiles()) {
+            if (i.isDirectory()) {
+                data = IrisData.get(i);
+                for (T j : data.getLoader(type).loadAll(data.getLoader(type).getPossibleKeys())) {
+                    if (known.add(j.getLoadKey()))
+                        p.add(j);
+                }
+            }
+        }
+
+        return p;
+    }
+
+    @Override
+    public String toString(T t) {
+        return t != null ? t.getLoadKey() : "null";
+    }
+
+    @Override
+    public T parse(String in, boolean force) throws DecreeParsingException {
+        if (in.equals("null") && nullable) {
+            return null;
+        }
+        KList<T> options = getPossibilities(in);
+        if (options.isEmpty()) {
+            throw new DecreeParsingException("Unable to find " + name + " \"" + in + "\"");
+        }
+
+        return options.stream()
+                .filter((i) -> toString(i).equalsIgnoreCase(in))
+                .findFirst()
+                .orElseThrow(() -> new DecreeParsingException("Unable to filter which " + name + " \"" + in + "\""));
+    }
+
+    @Override
+    public boolean supports(Class<?> type) {
+        return type.equals(this.type);
+    }
+}

core/src/main/java/com/volmit/iris/util/decree/virtual/VirtualDecreeCommand.java

@@ -478,14 +478,17 @@ public class VirtualDecreeCommand {
         }
 
         DecreeContext.touch(sender);
-        Runnable rx = () -> {
         try {
+            Runnable rx = () -> {
                 DecreeContext.touch(sender);
+                try {
                     getNode().getMethod().setAccessible(true);
                     getNode().getMethod().invoke(getNode().getInstance(), params);
                 } catch (Throwable e) {
                     e.printStackTrace();
                     throw new RuntimeException("Failed to execute <INSERT REAL NODE HERE>"); // TODO:
+                } finally {
+                    DecreeContext.remove();
                 }
             };
 
@@ -494,6 +497,9 @@ public class VirtualDecreeCommand {
             } else {
                 rx.run();
             }
+        } finally {
+            DecreeContext.remove();
+        }
 
         return true;
     }

core/src/main/java/com/volmit/iris/util/io/IO.java

@@ -179,6 +179,8 @@ public class IO {
         JsonElement json;
         try (FileReader reader = new FileReader(file)) {
             json = JsonParser.parseReader(reader);
+        } catch (Throwable e) {
+            throw new IOException("Failed to read json file " + file, e);
         }
 
         var queue = new LinkedList<JsonElement>();
@@ -1705,6 +1707,7 @@ public class IO {
                 action.accept(out);
             }
             Files.copy(temp.toPath(), Channels.newOutputStream(target));
+            target.truncate(temp.length());
         } finally {
             temp.delete();
         }

core/src/main/java/com/volmit/iris/util/io/ReactiveFolder.java

@@ -46,8 +46,8 @@ public class ReactiveFolder {
 
         if (checkCycle % 3 == 0 ? fw.checkModified() : fw.checkModifiedFast()) {
             for (File i : fw.getCreated()) {
-                if (i.getName().endsWith(".iob") || i.getName().endsWith(".json") || i.getName().endsWith(".js")) {
-                    if (i.getPath().contains(".iris")) {
+                if (i.getName().endsWith(".iob") || i.getName().endsWith(".json") || i.getName().endsWith(".kts")) {
+                    if (i.getPath().contains(".iris") || i.getName().endsWith(".gradle.kts")) {
                         continue;
                     }
 
@@ -58,11 +58,11 @@ public class ReactiveFolder {
 
             if (!modified) {
                 for (File i : fw.getChanged()) {
-                    if (i.getPath().contains(".iris")) {
+                    if (i.getPath().contains(".iris") || i.getName().endsWith(".gradle.kts")) {
                         continue;
                     }
 
-                    if (i.getName().endsWith(".iob") || i.getName().endsWith(".json") || i.getName().endsWith(".js")) {
+                    if (i.getName().endsWith(".iob") || i.getName().endsWith(".json") || i.getName().endsWith(".kts")) {
                         modified = true;
                         break;
                     }
@@ -71,11 +71,11 @@ public class ReactiveFolder {
 
             if (!modified) {
                 for (File i : fw.getDeleted()) {
-                    if (i.getPath().contains(".iris")) {
+                    if (i.getPath().contains(".iris") || i.getName().endsWith(".gradle.kts")) {
                         continue;
                     }
 
-                    if (i.getName().endsWith(".iob") || i.getName().endsWith(".json") || i.getName().endsWith(".js")) {
+                    if (i.getName().endsWith(".iob") || i.getName().endsWith(".json") || i.getName().endsWith(".kts")) {
                         modified = true;
                         break;
                     }

core/src/main/java/com/volmit/iris/util/mantle/MantleChunk.java

@@ -181,6 +181,11 @@ public class MantleChunk {
         }
     }
 
+    public void raiseFlagUnchecked(MantleFlag flag, Runnable r) {
+        if (closed.get()) throw new IllegalStateException("Chunk is closed!");
+        if (flags.compareAndSet(flag.ordinal(), false, true)) r.run();
+    }
+
     public boolean isFlagged(MantleFlag flag) {
         return flags.get(flag.ordinal());
     }
@@ -266,7 +271,7 @@ public class MantleChunk {
         dos.writeByte(x);
         dos.writeByte(z);
         dos.writeByte(sections.length());
-        Varint.writeUnsignedVarInt(Math.ceilDiv(flags.length(), Byte.SIZE), dos);
+        Varint.writeUnsignedVarInt(flags.length(), dos);
 
         int count = flags.length();
         for (int i = 0; i < count;) {

core/src/main/java/com/volmit/iris/util/misc/Bindings.java

@@ -1,5 +1,7 @@
 package com.volmit.iris.util.misc;
 
+import com.google.gson.JsonSyntaxException;
+import com.volmit.iris.BuildConstants;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.IrisSettings;
 import com.volmit.iris.core.nms.INMS;
@@ -19,19 +21,12 @@ import net.kyori.adventure.platform.bukkit.BukkitAudiences;
 import net.kyori.adventure.text.serializer.ComponentSerializer;
 import org.bstats.bukkit.Metrics;
 import org.bstats.charts.DrilldownPie;
-import org.bstats.charts.SimplePie;
 import org.bstats.charts.SingleLineChart;
 import org.bukkit.Bukkit;
 import org.bukkit.command.CommandSender;
-import org.bukkit.configuration.file.YamlConfiguration;
 import org.bukkit.entity.Player;
-import oshi.SystemInfo;
 
-import java.io.InputStreamReader;
-import java.math.RoundingMode;
-import java.text.NumberFormat;
 import java.util.HashMap;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.stream.Collectors;
@@ -47,8 +42,6 @@ public class Bindings {
         if (settings.disableAutoReporting || Sentry.isEnabled() || Boolean.getBoolean("iris.suppressReporting")) return;
         Iris.info("Enabling Sentry for anonymous error reporting. You can disable this in the settings.");
         Iris.info("Your server ID is: " + ServerID.ID);
-        var resource = Iris.instance.getResource("plugin.yml");
-        YamlConfiguration desc = resource != null ? YamlConfiguration.loadConfiguration(new InputStreamReader(resource)) : new YamlConfiguration();
 
         Sentry.init(options -> {
             options.setDsn("http://4cdbb9ac953306529947f4ca1e8e6b26@sentry.volmit.com:8080/2");
@@ -60,7 +53,7 @@ public class Bindings {
             options.setAttachServerName(false);
             options.setEnableUncaughtExceptionHandler(false);
             options.setRelease(Iris.instance.getDescription().getVersion());
-            options.setEnvironment(desc.getString("environment", "production"));
+            options.setEnvironment(BuildConstants.ENVIRONMENT);
             options.setBeforeSend((event, hint) -> {
                 if (suppress(event.getThrowable())) return null;
                 event.setTag("iris.safeguard", IrisSafeguard.mode());
@@ -77,12 +70,14 @@ public class Bindings {
             scope.setTag("server", Bukkit.getVersion());
             scope.setTag("server.type", Bukkit.getName());
             scope.setTag("server.api", Bukkit.getBukkitVersion());
-            scope.setTag("iris.commit", desc.getString("commit", "unknown"));
+            scope.setTag("iris.commit", BuildConstants.COMMIT);
         });
     }
 
     private static boolean suppress(Throwable e) {
-        return (e instanceof IllegalStateException ex && "zip file closed".equals(ex.getMessage())) || e instanceof JSONException;
+        return (e instanceof IllegalStateException ex && "zip file closed".equals(ex.getMessage()))
+                || e instanceof JSONException
+                || e instanceof JsonSyntaxException;
     }
 
 
@@ -99,6 +94,7 @@ public class Bindings {
                     .map(IrisToolbelt::access)
                     .filter(Objects::nonNull)
                     .map(PlatformChunkGenerator::getEngine)
+                    .filter(Objects::nonNull)
                     .collect(Collectors.toMap(engine -> engine.getDimension().getLoadKey(), engine -> {
                         var hash32 = engine.getHash32().getNow(null);
                         if (hash32 == null) return Map.of();
@@ -111,23 +107,7 @@ public class Bindings {
                         b.forEach((k, v) -> merged.merge(k, v, Integer::sum));
                         return merged;
                     }))));
-
-
-            var info = new SystemInfo().getHardware();
-            var cpu = info.getProcessor().getProcessorIdentifier();
-            var mem = info.getMemory();
-            metrics.addCustomChart(new SimplePie("cpu_model", cpu::getName));
-
-            var nf = NumberFormat.getInstance(Locale.ENGLISH);
-            nf.setMinimumFractionDigits(0);
-            nf.setMaximumFractionDigits(2);
-            nf.setRoundingMode(RoundingMode.HALF_UP);
-
-            metrics.addCustomChart(new DrilldownPie("memory", () -> {
-                double total = mem.getTotal() * 1E-9;
-                double alloc = Math.min(total, Runtime.getRuntime().maxMemory() * 1E-9);
-                return Map.of(nf.format(alloc), Map.of(nf.format(total), 1));
-            }));
+            metrics.addCustomChart(new DrilldownPie("environment", () -> Map.of(BuildConstants.ENVIRONMENT, Map.of(BuildConstants.COMMIT, 1))));
 
             plugin.postShutdown(metrics::shutdown);
         });

core/src/main/resources/plugin.yml

@@ -5,8 +5,6 @@ load: STARTUP
 authors: [ cyberpwn, NextdoorPsycho, Vatuu ]
 website: volmit.com
 description: More than a Dimension!
-environment: '${environment}'
-commit: '${commit}'
 commands:
   iris:
     aliases: [ ir, irs ]

core/src/main/templates/BuildConstants.java

@@ -0,0 +1,7 @@
+package com.volmit.iris;
+
+// The constants are replaced before compilation
+public interface BuildConstants {
+    String ENVIRONMENT = "${environment}";
+    String COMMIT = "${commit}";
+}

gradle/libs.versions.toml

@@ -27,6 +27,7 @@ sentry = "8.14.0" # https://github.com/getsentry/sentry-java
 commons-io = "2.19.0" # https://central.sonatype.com/artifact/commons-io/commons-io
 commons-lang = "2.6" # https://central.sonatype.com/artifact/commons-lang/commons-lang
 commons-lang3 = "3.17.0" # https://central.sonatype.com/artifact/org.apache.commons/commons-lang3
+commons-math3 = "3.6.1"
 oshi = "6.8.2" # https://central.sonatype.com/artifact/com.github.oshi/oshi-core
 fastutil = "8.5.16" # https://central.sonatype.com/artifact/it.unimi.dsi/fastutil
 lz4 = "1.8.0" # https://central.sonatype.com/artifact/org.lz4/lz4-java
@@ -78,6 +79,7 @@ sentry = { module = "io.sentry:sentry", version.ref = "sentry" }
 commons-io = { module = "commons-io:commons-io", version.ref = "commons-io" }
 commons-lang = { module = "commons-lang:commons-lang", version.ref = "commons-lang" }
 commons-lang3 = { module = "org.apache.commons:commons-lang3", version.ref = "commons-lang3" }
+commons-math3 = { module = "org.apache.commons:commons-math3", version.ref = "commons-math3" }
 oshi = { module = "com.github.oshi:oshi-core", version.ref = "oshi" }
 lz4 = { module = "org.lz4:lz4-java", version.ref = "lz4" }
 fastutil = { module = "it.unimi.dsi:fastutil", version.ref = "fastutil" }

nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/IrisChunkGenerator.java

@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,45 +29,55 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R1.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R1.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R1.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -182,8 +194,58 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var structure = registry.getOptional(loc).orElse(null);
+            if (structure == null) return false;
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure, registryAccess),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -201,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -213,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -236,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinBuildHeight(), column);
     }
 
     static {
@@ -251,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/NMSBinding.java

@@ -3,11 +3,14 @@ package com.volmit.iris.core.nms.v1_20_R1;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -58,6 +61,8 @@ import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import org.bukkit.*;
 import org.bukkit.block.Biome;
 import org.bukkit.block.data.BlockData;
@@ -78,7 +83,6 @@ import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 
-import java.awt.*;
 import java.awt.Color;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
@@ -89,6 +93,7 @@ import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 
 public class NMSBinding implements INMSBinding {
 
@@ -703,6 +708,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.registryKeySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/IrisChunkGenerator.java

@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,45 +29,55 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R2.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R2.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R2.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -182,8 +194,58 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var structure = registry.getOptional(loc).orElse(null);
+            if (structure == null) return false;
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure, registryAccess),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -201,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -213,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -236,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinBuildHeight(), column);
     }
 
     static {
@@ -251,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/NMSBinding.java

@@ -1,9 +1,26 @@
 package com.volmit.iris.core.nms.v1_20_R2;
 
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import java.awt.Color;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.engine.data.cache.AtomicCache;
@@ -21,6 +38,8 @@ import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
+import com.volmit.iris.core.nms.container.StructurePlacement;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import net.bytebuddy.ByteBuddy;
@@ -58,6 +77,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -707,6 +728,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.registryKeySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/IrisChunkGenerator.java

@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,45 +29,55 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R3.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R3.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R3.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -182,8 +194,58 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var structure = registry.getOptional(loc).orElse(null);
+            if (structure == null) return false;
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -201,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -213,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -236,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinBuildHeight(), column);
     }
 
     static {
@@ -251,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/NMSBinding.java

@@ -1,9 +1,26 @@
 package com.volmit.iris.core.nms.v1_20_R3;
 
+import java.awt.Color;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.engine.data.cache.AtomicCache;
@@ -21,6 +38,8 @@ import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
+import com.volmit.iris.core.nms.container.StructurePlacement;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import net.bytebuddy.ByteBuddy;
@@ -58,6 +77,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -708,6 +729,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.registryKeySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/IrisChunkGenerator.java

@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,43 +29,53 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R4.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R4.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R4.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.*;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -180,8 +192,59 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.getHolder(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -199,11 +262,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -211,7 +269,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -234,9 +360,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinBuildHeight(), column);
     }
 
     static {
@@ -249,7 +388,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/NMSBinding.java

@@ -1,11 +1,25 @@
 package com.volmit.iris.core.nms.v1_20_R4;
 
+import java.awt.Color;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
@@ -21,6 +35,7 @@ import com.volmit.iris.util.math.Vector3d;
 import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import net.bytebuddy.ByteBuddy;
@@ -58,6 +73,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -725,6 +742,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/IrisChunkGenerator.java

@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,44 +29,54 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R1.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R1.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R1.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -181,8 +193,59 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.getHolder(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -200,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -212,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -235,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinBuildHeight(), column);
     }
 
     static {
@@ -250,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/NMSBinding.java

@@ -1,12 +1,31 @@
 package com.volmit.iris.core.nms.v1_21_R1;
 
+import java.awt.Color;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
@@ -63,6 +82,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -737,6 +758,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/IrisChunkGenerator.java

@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,43 +29,54 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R2.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R2.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R2.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -180,8 +193,59 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -199,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -211,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -234,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinY() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinY(), column);
     }
 
     static {
@@ -249,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/NMSBinding.java

@@ -1,9 +1,24 @@
 package com.volmit.iris.core.nms.v1_21_R2;
 
+import java.awt.Color;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
@@ -21,6 +36,7 @@ import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import it.unimi.dsi.fastutil.shorts.ShortList;
@@ -60,6 +76,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -734,6 +752,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/IrisChunkGenerator.java

@@ -8,12 +8,17 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
 import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -26,38 +31,49 @@ import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
 import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.*;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BuiltinStructures;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
 import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R3.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R3.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R3.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 import org.spigotmc.SpigotWorldConfig;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.lang.reflect.Method;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -174,8 +190,61 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager, ResourceKey<Level> resourcekey) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager, resourcekey);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    holder,
+                    levelKey,
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    biome -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -208,11 +277,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -220,7 +284,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
     }
 
     @Override
@@ -230,22 +294,70 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, vanilla);
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
     }
 
     @Override
-    public int getFirstFreeHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstFreeHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
         }
 
-    @Override
-    public int getFirstOccupiedHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstOccupiedHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
         }
 
-    @Override
-    public void addVanillaDecorations(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -263,9 +375,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinY() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinY(), column);
     }
 
     @Override
@@ -294,7 +419,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/NMSBinding.java

@@ -2,12 +2,17 @@ package com.volmit.iris.core.nms.v1_21_R3;
 
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructure;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -60,6 +65,9 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -88,10 +96,16 @@ import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.*;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 public class NMSBinding implements INMSBinding {
     private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -178,14 +192,14 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Contract(value = "null, _, _ -> null", pure = true)
-    private Object convertFromTag(net.minecraft.nbt.Tag tag, int depth, int maxDepth) {
+    private Object convertFromTag(Tag tag, int depth, int maxDepth) {
         if (tag == null || depth > maxDepth) return null;
         return switch (tag) {
             case CollectionTag<?> collection -> {
                 KList<Object> list = new KList<>();
 
                 for (Object i : collection) {
-                    if (i instanceof net.minecraft.nbt.Tag t)
+                    if (i instanceof Tag t)
                         list.add(convertFromTag(t, depth + 1, maxDepth));
                     else list.add(i);
                 }
@@ -242,7 +256,7 @@ public class NMSBinding implements INMSBinding {
                 yield tag;
             }
             case List<?> list -> {
-                var tag = new net.minecraft.nbt.ListTag();
+                var tag = new ListTag();
                 for (var i : list) {
                     tag.add(convertToTag(i, depth + 1, maxDepth));
                 }
@@ -496,13 +510,13 @@ public class NMSBinding implements INMSBinding {
     @Override
     public MCAPaletteAccess createPalette() {
         MCAIdMapper<BlockState> registry = registryCache.aquireNasty(() -> {
-            Field cf = net.minecraft.core.IdMapper.class.getDeclaredField("tToId");
-            Field df = net.minecraft.core.IdMapper.class.getDeclaredField("idToT");
-            Field bf = net.minecraft.core.IdMapper.class.getDeclaredField("nextId");
+            Field cf = IdMapper.class.getDeclaredField("tToId");
+            Field df = IdMapper.class.getDeclaredField("idToT");
+            Field bf = IdMapper.class.getDeclaredField("nextId");
             cf.setAccessible(true);
             df.setAccessible(true);
             bf.setAccessible(true);
-            net.minecraft.core.IdMapper<BlockState> blockData = Block.BLOCK_STATE_REGISTRY;
+            IdMapper<BlockState> blockData = Block.BLOCK_STATE_REGISTRY;
             int b = bf.getInt(blockData);
             Object2IntMap<BlockState> c = (Object2IntMap<BlockState>) cf.get(blockData);
             List<BlockState> d = (List<BlockState>) df.get(blockData);
@@ -600,7 +614,7 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    public java.awt.Color getBiomeColor(Location location, BiomeColor type) {
+    public Color getBiomeColor(Location location, BiomeColor type) {
         LevelReader reader = ((CraftWorld) location.getWorld()).getHandle();
         var holder = reader.getBiome(new BlockPos(location.getBlockX(), location.getBlockY(), location.getBlockZ()));
         var biome = holder.value();
@@ -733,6 +747,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a,b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_21_R4/src/main/java/com/volmit/iris/core/nms/v1_21_R4/IrisChunkGenerator.java

@@ -8,12 +8,17 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
 import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -26,38 +31,48 @@ import net.minecraft.util.random.WeightedList;
 import net.minecraft.world.entity.MobCategory;
 import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.*;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
 import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R4.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R4.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R4.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 import org.spigotmc.SpigotWorldConfig;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.lang.reflect.Method;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -174,8 +189,61 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager, ResourceKey<Level> resourcekey) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager, resourcekey);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    holder,
+                    levelKey,
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    biome -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -208,11 +276,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -220,7 +283,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
     }
 
     @Override
@@ -230,22 +293,70 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, vanilla);
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
     }
 
     @Override
-    public int getFirstFreeHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstFreeHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
         }
 
-    @Override
-    public int getFirstOccupiedHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstOccupiedHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
         }
 
-    @Override
-    public void addVanillaDecorations(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -263,9 +374,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinY() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinY(), column);
     }
 
     @Override
@@ -294,7 +418,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_21_R4/src/main/java/com/volmit/iris/core/nms/v1_21_R4/NMSBinding.java

@@ -2,12 +2,16 @@ package com.volmit.iris.core.nms.v1_21_R4;
 
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -60,6 +64,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -92,6 +98,7 @@ import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 
 public class NMSBinding implements INMSBinding {
     private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -733,6 +740,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");

nms/v1_21_R5/src/main/java/com/volmit/iris/core/nms/v1_21_R5/IrisChunkGenerator.java

@@ -8,12 +8,17 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
 import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -26,38 +31,48 @@ import net.minecraft.util.random.WeightedList;
 import net.minecraft.world.entity.MobCategory;
 import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.*;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
 import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R5.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R5.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R5.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 import org.spigotmc.SpigotWorldConfig;
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.lang.reflect.Method;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;
 
 public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
     private final KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
         super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
         var dimension = engine.getDimension();
 
         KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -174,8 +189,61 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager, ResourceKey<Level> resourcekey) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager, resourcekey);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    holder,
+                    levelKey,
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    biome -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
     }
 
     @Override
@@ -208,11 +276,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
     }
 
-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
     @Override
     public WeightedList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
         return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -220,7 +283,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
     }
 
     @Override
@@ -230,22 +293,70 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, vanilla);
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
     }
 
     @Override
-    public int getFirstFreeHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstFreeHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
         }
 
-    @Override
-    public int getFirstOccupiedHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstOccupiedHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
         }
 
-    @Override
-    public void addVanillaDecorations(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
     }
 
     @Override
@@ -263,9 +374,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         return delegate.getGenDepth();
     }
 
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinY() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
     @Override
     public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, randomstate);
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinY(), column);
     }
 
     @Override
@@ -294,7 +418,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         }
         if (biomeSource == null)
             throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
         BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
     }
 
     private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {

nms/v1_21_R5/src/main/java/com/volmit/iris/core/nms/v1_21_R5/NMSBinding.java

@@ -2,12 +2,16 @@ package com.volmit.iris.core.nms.v1_21_R5;
 
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -60,6 +64,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -92,6 +98,7 @@ import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 
 public class NMSBinding implements INMSBinding {
     private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -733,6 +740,71 @@ public class NMSBinding implements INMSBinding {
         return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
     }
 
+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a, b) -> a, KMap::new));
+    }
+
     public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
         if (!(raw instanceof PlatformChunkGenerator gen))
             throw new IllegalStateException("Generator is not platform chunk generator!");