Leaf/leaf-server/minecraft-patches/features/0185-optimise-NaturalSpawner-spawnForChunk.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: hayanesuru <hayanesuru@outlook.jp>
Date: Tue, 3 Jun 2025 15:20:59 +0900
Subject: [PATCH] optimise NaturalSpawner#spawnForChunk


diff --git a/net/minecraft/world/level/NaturalSpawner.java b/net/minecraft/world/level/NaturalSpawner.java
index c0d941af10ffe8c158dab9db40c7c5767b6cfd6e..450f17badaa3f6c8f1cdb9e6dc76828b70afe6fc 100644
--- a/net/minecraft/world/level/NaturalSpawner.java
+++ b/net/minecraft/world/level/NaturalSpawner.java
@@ -238,10 +238,13 @@ public final class NaturalSpawner {
         // Paper end - throttle failed spawn attempts
     ) {
         // Paper end - Optional per player mob spawns
-        BlockPos randomPosWithin = getRandomPosWithin(level, chunk);
-        if (randomPosWithin.getY() >= level.getMinY() + 1) {
-            return spawnCategoryForPosition(category, level, chunk, randomPosWithin, filter, callback, maxSpawns, trackEntity, false); // Paper - Optional per player mob spawns // Paper - throttle failed spawn attempts
+        // Leaf start
+        BlockPos.MutableBlockPos pos = new BlockPos.MutableBlockPos();
+        mutableRandomPosWithin(pos, level, chunk);
+        if (pos.getY() >= level.getMinY() + 1) {
+            return spawnCategoryForPosition(category, level, chunk, pos, filter, callback, maxSpawns, trackEntity, false); // Paper - Optional per player mob spawns // Paper - throttle failed spawn attempts
         }
+        // Leaf end
 
         return 0; // Paper - throttle failed spawn attempts
     }
@@ -275,31 +278,60 @@ public final class NaturalSpawner {
         StructureManager structureManager = level.structureManager();
         ChunkGenerator generator = level.getChunkSource().getGenerator();
         int y = pos.getY();
+        int posX = pos.getX(); // Leaf
+        int posZ = pos.getZ(); // Leaf
         int i = 0; // Paper - throttle failed spawn attempts
-        BlockState blockState = level.getBlockStateIfLoadedAndInBounds(pos); // Paper - don't load chunks for mob spawn
+        // Leaf start
+        if (!level.getWorldBorder().isWithinBounds(pos) || level.isOutsideBuildHeight(pos)) {
+            return i;
+        }
+        BlockState blockState = chunk.getPos().longKey == ChunkPos.asLong(pos) ? chunk.getBlockState(posX, y, posZ) : level.getBlockStateIfLoaded(pos);
+        // Leaf end
         if (blockState != null && !blockState.isRedstoneConductor(chunk, pos)) { // Paper - don't load chunks for mob spawn
-            BlockPos.MutableBlockPos mutableBlockPos = new BlockPos.MutableBlockPos();
+            BlockPos.MutableBlockPos mutableBlockPos = pos instanceof BlockPos.MutableBlockPos pos2 ? pos2 : new BlockPos.MutableBlockPos(); // Leaf
             //int i = 0; // Paper - throttle failed spawn attempts - move up
 
+            // Leaf start
+            long rand = level.random.nextLong();
+            int bits = 0;
             for (int i1 = 0; i1 < 3; i1++) {
-                int x = pos.getX();
-                int z = pos.getZ();
-                int i2 = 6;
+                int x = posX;
+                int z = posZ;
                 MobSpawnSettings.SpawnerData spawnerData = null;
                 SpawnGroupData spawnGroupData = null;
-                int ceil = Mth.ceil(level.random.nextFloat() * 4.0F);
+                int ceil = (int) ((rand & 0x3L) + 1L);
+                bits += 2;
                 int i3 = 0;
 
                 for (int i4 = 0; i4 < ceil; i4++) {
-                    x += level.random.nextInt(6) - level.random.nextInt(6);
-                    z += level.random.nextInt(6) - level.random.nextInt(6);
+                    int rand1=0,rand2=0,rand3=0,rand4=0,valuesNeeded=4;
+                    while (valuesNeeded > 0) {
+                        if (bits > 61) {
+                            rand = level.random.nextLong();
+                            bits = 0;
+                        }
+                        int threeBits = (int) ((rand >>> bits) & 0x7L);
+                        bits += 3;
+                        if (threeBits != 7 && threeBits != 6) {
+                            switch (valuesNeeded) {
+                                case 1 -> rand4 = threeBits;
+                                case 2 -> rand3 = threeBits;
+                                case 3 -> rand2 = threeBits;
+                                case 4 -> rand1 = threeBits;
+                            }
+                            valuesNeeded--;
+                        }
+                    }
+                    x += rand1 - rand2;
+                    z += rand3 - rand4;
+                    // Leaf end
                     mutableBlockPos.set(x, y, z);
                     double d = x + 0.5;
                     double d1 = z + 0.5;
                     Player nearestPlayer = level.getNearestPlayer(d, y, d1, -1.0, level.purpurConfig.mobSpawningIgnoreCreativePlayers); // Purpur - mob spawning option to ignore creative players
                     if (nearestPlayer != null) {
                         double d2 = nearestPlayer.distanceToSqr(d, y, d1);
-                        if (level.isLoadedAndInBounds(mutableBlockPos) && isRightDistanceToPlayerAndSpawnPoint(level, chunk, mutableBlockPos, d2)) { // Paper - don't load chunks for mob spawn
+                        if (level.getWorldBorder().isWithinBounds(mutableBlockPos) && (chunk.getPos().longKey == ChunkPos.asLong(mutableBlockPos) || level.getChunkIfLoadedImmediately(mutableBlockPos.getX() >> 4, mutableBlockPos.getZ() >> 4) != null) && isRightDistanceToPlayerAndSpawnPoint(level, chunk, mutableBlockPos, d2)) { // Paper - don't load chunks for mob spawn // Leaf
                             if (spawnerData == null) {
                                 Optional<MobSpawnSettings.SpawnerData> randomSpawnMobAt = getRandomSpawnMobAt(
                                     level, structureManager, generator, category, level.random, mutableBlockPos
@@ -368,8 +400,8 @@ public final class NaturalSpawner {
 
     private static boolean isRightDistanceToPlayerAndSpawnPoint(ServerLevel level, ChunkAccess chunk, BlockPos.MutableBlockPos pos, double distance) {
         return !(distance <= 576.0)
-            && !level.getSharedSpawnPos().closerToCenterThan(new Vec3(pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5), 24.0)
-            && (Objects.equals(new ChunkPos(pos), chunk.getPos()) || level.isNaturalSpawningAllowed(pos));
+            && !(level.getSharedSpawnPos().distToCenterSqr(pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5) < 576.0) // Leaf
+            && (ChunkPos.asLong(pos) == chunk.getPos().longKey || level.isNaturalSpawningAllowed(pos)); // Leaf
     }
 
     // Paper start - PreCreatureSpawnEvent
@@ -474,6 +506,17 @@ public final class NaturalSpawner {
         }
     }
 
+    // Leaf start
+    private static void mutableRandomPosWithin(BlockPos.MutableBlockPos pos1, Level level, LevelChunk chunk) {
+        ChunkPos pos = chunk.getPos();
+        int i = pos.getMinBlockX() + level.random.nextInt(16);
+        int i1 = pos.getMinBlockZ() + level.random.nextInt(16);
+        int i2 = chunk.getHeight(Heightmap.Types.WORLD_SURFACE, i, i1) + 1;
+        int i3 = Mth.randomBetweenInclusive(level.random, level.getMinY(), i2);
+        pos1.set(i, i3, i1);
+    }
+    // Leaf end
+
     private static BlockPos getRandomPosWithin(Level level, LevelChunk chunk) {
         ChunkPos pos = chunk.getPos();
         int i = pos.getMinBlockX() + level.random.nextInt(16);