Experimental caching noise biome source

Author: embeddedt

common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/worldgen_allocation/SurfaceSystemMixin.java

@@ -0,0 +1,31 @@
+package org.embeddedt.modernfix.common.mixin.perf.worldgen_allocation;
+
+import com.llamalad7.mixinextras.sugar.Local;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.QuartPos;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.BiomeManager;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.levelgen.SurfaceSystem;
+import org.embeddedt.modernfix.world.gen.CachingNoiseBiomeSource;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+
+import java.util.function.Function;
+
+@Mixin(SurfaceSystem.class)
+public class SurfaceSystemMixin {
+    @ModifyArg(method = "buildSurface", at = @At(value = "INVOKE", target = "Lnet/minecraft/world/level/levelgen/SurfaceRules$Context;<init>(Lnet/minecraft/world/level/levelgen/SurfaceSystem;Lnet/minecraft/world/level/levelgen/RandomState;Lnet/minecraft/world/level/chunk/ChunkAccess;Lnet/minecraft/world/level/levelgen/NoiseChunk;Ljava/util/function/Function;Lnet/minecraft/core/Registry;Lnet/minecraft/world/level/levelgen/WorldGenerationContext;)V"), index = 4)
+    private Function<BlockPos, Holder<Biome>> createBiomeManagerBoundToChunk(Function<BlockPos, Holder<Biome>> biomeGetter, @Local(ordinal = 0, argsOnly = true) BiomeManager manager, @Local(ordinal = 0, argsOnly = true) ChunkAccess chunk) {
+        var chunkPos = chunk.getPos();
+        return manager.withDifferentSource(new CachingNoiseBiomeSource(
+                manager::getNoiseBiomeAtQuart,
+                QuartPos.fromSection(chunkPos.x),
+                QuartPos.fromSection(chunkPos.z),
+                chunk.getHeight(),
+                Math.abs(chunk.getMinBuildHeight())
+        ))::getBiome;
+    }
+}

common/src/main/java/org/embeddedt/modernfix/world/gen/CachingNoiseBiomeSource.java

@@ -0,0 +1,53 @@
+package org.embeddedt.modernfix.world.gen;
+
+import net.minecraft.core.Holder;
+import net.minecraft.core.QuartPos;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.BiomeManager;
+
+public class CachingNoiseBiomeSource implements BiomeManager.NoiseBiomeSource {
+    private static final boolean DEBUG_OOB = false;
+    private static final int HORIZONTAL_CELLS_PER_CHUNK = 8;
+    private static final int CELL_SHIFT = 2;
+    private final BiomeManager.NoiseBiomeSource biomeSource;
+    private final Holder<Biome>[] biomesInCells;
+    private final int numVerticalCells;
+    private final int verticalShift;
+    private final int chunkOriginX, chunkOriginZ;
+
+    public CachingNoiseBiomeSource(BiomeManager.NoiseBiomeSource backingSource, int chunkOriginX, int chunkOriginZ, int worldHeight, int numBlocksBelowYZero) {
+        this.biomeSource = backingSource;
+        this.numVerticalCells = worldHeight / QuartPos.SIZE + 2;
+        this.chunkOriginX = chunkOriginX;
+        this.chunkOriginZ = chunkOriginZ;
+        this.verticalShift = numBlocksBelowYZero / QuartPos.SIZE;
+        this.biomesInCells = new Holder[numVerticalCells * HORIZONTAL_CELLS_PER_CHUNK * HORIZONTAL_CELLS_PER_CHUNK];
+    }
+
+    private static int getLocalIndex(int relX, int relY, int relZ) {
+        return (relY * HORIZONTAL_CELLS_PER_CHUNK * HORIZONTAL_CELLS_PER_CHUNK) + (relZ * HORIZONTAL_CELLS_PER_CHUNK) + relX;
+    }
+
+    @Override
+    public Holder<Biome> getNoiseBiome(int x, int y, int z) {
+        int relX = x + CELL_SHIFT - this.chunkOriginX;
+        int relZ = z + CELL_SHIFT - this.chunkOriginZ;
+        int relY = y + this.verticalShift + 1;
+        if (((relX | relZ) & ~(HORIZONTAL_CELLS_PER_CHUNK - 1)) != 0 || relY < 0 || relY >= this.numVerticalCells) {
+            return this.biomeSource.getNoiseBiome(x, y, z);
+        }
+        int i = getLocalIndex(relX, relY, relZ);
+        if (DEBUG_OOB) {
+            if (i < 0 || i >= this.biomesInCells.length) {
+                throw new ArrayIndexOutOfBoundsException("Error: Requested noise biome cell is out of range: (%d, %d, %d)".formatted(relX, relY, relZ));
+            }
+        }
+        var biomes = this.biomesInCells;
+        var result = biomes[i];
+        if (result == null) {
+            result = this.biomeSource.getNoiseBiome(x, y, z);
+            biomes[i] = result;
+        }
+        return result;
+    }
+}