SakuraMC/patches/server/0018-Store-Entity-Data-State.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Samsuik <40902469+Samsuik@users.noreply.github.com>
Date: Wed, 16 Aug 2023 22:34:49 +0100
Subject: [PATCH] Store Entity Data/State


diff --git a/src/main/java/me/samsuik/sakura/entity/EntityState.java b/src/main/java/me/samsuik/sakura/entity/EntityState.java
new file mode 100644
index 0000000000000000000000000000000000000000..c9f2c5ae57878283e8c8bc3847fe63b98f4e8d10
--- /dev/null
+++ b/src/main/java/me/samsuik/sakura/entity/EntityState.java
@@ -0,0 +1,41 @@
+package me.samsuik.sakura.entity;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.phys.AABB;
+import net.minecraft.world.phys.Vec3;
+
+import java.util.Optional;
+
+public record EntityState(Vec3 position, Vec3 momentum, AABB bb, Vec3 stuckSpeed, Optional<BlockPos> supportingPos, boolean onGround, float fallDistance) {
+
+    public static EntityState of(Entity entity) {
+        return new EntityState(entity.position(), entity.getDeltaMovement(), entity.getBoundingBox(), entity.stuckSpeedMultiplier(), entity.mainSupportingBlockPos, entity.onGround(), entity.fallDistance);
+    }
+
+    public void apply(Entity entity) {
+        entity.setPos(position);
+        entity.setDeltaMovement(momentum);
+        entity.setBoundingBox(bb);
+        // null here is only safe for our use case (tnt and sand)
+        //noinspection DataFlowIssue
+        entity.makeStuckInBlock(null, stuckSpeed);
+        entity.onGround = onGround;
+        entity.mainSupportingBlockPos = supportingPos;
+        entity.fallDistance = fallDistance;
+    }
+
+    public void position(Entity entity) {
+        entity.setPos(position);
+        entity.setBoundingBox(bb);
+    }
+
+    public boolean isCurrentState(Entity entity) {
+        return entity.position().equals(position)
+            && entity.getDeltaMovement().equals(momentum);
+            // 1.14+ versions seem to correct morphed bounding boxes after a gametick.
+            // If there are any related issues uncomment this line of code.
+            // && entity.getBoundingBox().equals(bb);
+    }
+
+}
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 7fad22ee8a24399acbae6a9bc07ad5de39d41020..393e951102c49d45a135b37ccd876283c5355710 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -550,6 +550,34 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
         return flags;
     }
     // Sakura end
+    // Sakura start - entity state (from start of tick)
+    private @Nullable me.samsuik.sakura.entity.EntityState entityState = null;
+
+    public Vec3 stuckSpeedMultiplier() {
+        return stuckSpeedMultiplier;
+    }
+
+    public void storeEntityState() {
+        entityState = me.samsuik.sakura.entity.EntityState.of(this);
+    }
+
+    public @Nullable me.samsuik.sakura.entity.EntityState entityState() {
+        return entityState;
+    }
+
+    public boolean compareState(Entity to) {
+        return to.entityState() != null && to.entityState().isCurrentState(this);
+    }
+
+    public long getPackedOrigin() {
+        var v = getOriginVector();
+        if (v == null) return Long.MIN_VALUE;
+        // Note: vector#getBlockN may not be 100% exact
+        // If there's any future issues at let's say 0.999999...
+        // giving an incorrect position change it to Mth instead.
+        return BlockPos.asLong(v.getBlockX(), v.getBlockY(), v.getBlockZ());
+    }
+    // Sakura end
 
     public boolean isLegacyTrackingEntity = false;
 
diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
index bf361855ecf8c1d5dee2e735278243b836bf0f2a..902ec524d209ab56a6dadb260559910c76dbf96b 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -1342,6 +1342,7 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
 
     public <T extends Entity> void guardEntityTick(Consumer<T> tickConsumer, T entity) {
         try {
+            entity.storeEntityState(); // Sakura - store entity state
             tickConsumer.accept(entity);
             MinecraftServer.getServer().executeMidTickTasks(); // Paper - execute chunk tasks mid tick
         } catch (Throwable throwable) {