Expose vanilla BiomeProvider from WorldInfo

paper-server/patches/sources/net/minecraft/server/MinecraftServer.java.patch

@@ -483,7 +483,7 @@
 +            List<CustomSpawner> list = ImmutableList.of(new PhantomSpawner(), new PatrolSpawner(), new CatSpawner(), new VillageSiege(), new WanderingTraderSpawner(iworlddataserver));
 +            LevelStem worlddimension = (LevelStem) dimensions.getValue(dimensionKey);
 +
-+            org.bukkit.generator.WorldInfo worldInfo = new org.bukkit.craftbukkit.generator.CraftWorldInfo(iworlddataserver, worldSession, org.bukkit.World.Environment.getEnvironment(dimension), worlddimension.type().value());
++            org.bukkit.generator.WorldInfo worldInfo = new org.bukkit.craftbukkit.generator.CraftWorldInfo(iworlddataserver, worldSession, org.bukkit.World.Environment.getEnvironment(dimension), worlddimension.type().value(), worlddimension.generator(), this.registryAccess()); // Paper - Expose vanilla BiomeProvider from WorldInfo
 +            if (biomeProvider == null && gen != null) {
 +                biomeProvider = gen.getDefaultBiomeProvider(worldInfo);
 +            }

paper-server/patches/sources/net/minecraft/server/level/ServerLevel.java.patch

@@ -212,7 +212,7 @@
 +        this.serverLevelData.setWorld(this);
 +
 +        if (biomeProvider != null) {
-+            BiomeSource worldChunkManager = new CustomWorldChunkManager(this.getWorld(), biomeProvider, this.server.registryAccess().lookupOrThrow(Registries.BIOME));
++            BiomeSource worldChunkManager = new CustomWorldChunkManager(this.getWorld(), biomeProvider, this.server.registryAccess().lookupOrThrow(Registries.BIOME), chunkgenerator.getBiomeSource()); // Paper - add vanillaBiomeProvider
 +            if (chunkgenerator instanceof NoiseBasedChunkGenerator cga) {
 +                chunkgenerator = new NoiseBasedChunkGenerator(worldChunkManager, cga.settings);
 +            } else if (chunkgenerator instanceof FlatLevelSource cpf) {

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -1310,7 +1310,7 @@ public final class CraftServer implements Server {
         List<CustomSpawner> list = ImmutableList.of(new PhantomSpawner(), new PatrolSpawner(), new CatSpawner(), new VillageSiege(), new WanderingTraderSpawner(worlddata));
         LevelStem worlddimension = iregistry.getValue(actualDimension);
 
-        WorldInfo worldInfo = new CraftWorldInfo(worlddata, worldSession, creator.environment(), worlddimension.type().value());
+        WorldInfo worldInfo = new CraftWorldInfo(worlddata, worldSession, creator.environment(), worlddimension.type().value(), worlddimension.generator(), this.getHandle().getServer().registryAccess()); // Paper - Expose vanilla BiomeProvider from WorldInfo
         if (biomeProvider == null && generator != null) {
             biomeProvider = generator.getDefaultBiomeProvider(worldInfo);
         }

paper-server/src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -209,6 +209,39 @@ public class CraftWorld extends CraftRegionAccessor implements World {
     public int getPlayerCount() {
         return world.players().size();
     }
+
+    @Override
+    public BiomeProvider vanillaBiomeProvider() {
+        net.minecraft.server.level.ServerChunkCache serverCache = this.getHandle().chunkSource;
+
+        final net.minecraft.world.level.chunk.ChunkGenerator gen = serverCache.getGenerator();
+        net.minecraft.world.level.biome.BiomeSource biomeSource;
+        if (gen instanceof org.bukkit.craftbukkit.generator.CustomChunkGenerator custom) {
+            biomeSource = custom.getDelegate().getBiomeSource();
+        } else {
+            biomeSource = gen.getBiomeSource();
+        }
+        if (biomeSource instanceof org.bukkit.craftbukkit.generator.CustomWorldChunkManager customBiomeSource) {
+            biomeSource = customBiomeSource.vanillaBiomeSource;
+        }
+        final net.minecraft.world.level.biome.BiomeSource finalBiomeSource = biomeSource;
+        final net.minecraft.world.level.biome.Climate.Sampler sampler = serverCache.randomState().sampler();
+
+        final List<Biome> possibleBiomes = finalBiomeSource.possibleBiomes().stream()
+            .map(CraftBiome::minecraftHolderToBukkit)
+            .toList();
+        return new BiomeProvider() {
+            @Override
+            public Biome getBiome(final org.bukkit.generator.WorldInfo worldInfo, final int x, final int y, final int z) {
+                return CraftBiome.minecraftHolderToBukkit(finalBiomeSource.getNoiseBiome(x >> 2, y >> 2, z >> 2, sampler));
+            }
+
+            @Override
+            public List<Biome> getBiomes(final org.bukkit.generator.WorldInfo worldInfo) {
+                return possibleBiomes;
+            }
+        };
+    }
     // Paper end
 
     private static final Random rand = new Random();

paper-server/src/main/java/org/bukkit/craftbukkit/generator/CraftWorldInfo.java

@@ -17,8 +17,14 @@ public class CraftWorldInfo implements WorldInfo {
     private final long seed;
     private final int minHeight;
     private final int maxHeight;
+    // Paper start
+    private final net.minecraft.world.level.chunk.ChunkGenerator vanillaChunkGenerator;
+    private final net.minecraft.core.RegistryAccess.Frozen registryAccess;
 
-    public CraftWorldInfo(ServerLevelData worldDataServer, LevelStorageSource.LevelStorageAccess session, World.Environment environment, DimensionType dimensionManager) {
+    public CraftWorldInfo(PrimaryLevelData worldDataServer, LevelStorageSource.LevelStorageAccess session, World.Environment environment, DimensionType dimensionManager, net.minecraft.world.level.chunk.ChunkGenerator chunkGenerator, net.minecraft.core.RegistryAccess.Frozen registryAccess) {
+        this.registryAccess = registryAccess;
+        this.vanillaChunkGenerator = chunkGenerator;
+        // Paper end
         this.name = worldDataServer.getLevelName();
         this.uuid = WorldUUID.getUUID(session.levelDirectory.path().toFile());
         this.environment = environment;
@@ -27,15 +33,6 @@ public class CraftWorldInfo implements WorldInfo {
         this.maxHeight = dimensionManager.minY() + dimensionManager.height();
     }
 
-    public CraftWorldInfo(String name, UUID uuid, World.Environment environment, long seed, int minHeight, int maxHeight) {
-        this.name = name;
-        this.uuid = uuid;
-        this.environment = environment;
-        this.seed = seed;
-        this.minHeight = minHeight;
-        this.maxHeight = maxHeight;
-    }
-
     @Override
     public String getName() {
         return this.name;
@@ -65,4 +62,34 @@ public class CraftWorldInfo implements WorldInfo {
     public int getMaxHeight() {
         return this.maxHeight;
     }
+
+    // Paper start
+    @Override
+    public org.bukkit.generator.BiomeProvider vanillaBiomeProvider() {
+        final net.minecraft.world.level.levelgen.RandomState randomState;
+        if (vanillaChunkGenerator instanceof net.minecraft.world.level.levelgen.NoiseBasedChunkGenerator noiseBasedChunkGenerator) {
+            randomState = net.minecraft.world.level.levelgen.RandomState.create(noiseBasedChunkGenerator.generatorSettings().value(),
+                registryAccess.lookupOrThrow(net.minecraft.core.registries.Registries.NOISE), getSeed());
+        } else {
+            randomState = net.minecraft.world.level.levelgen.RandomState.create(net.minecraft.world.level.levelgen.NoiseGeneratorSettings.dummy(),
+                registryAccess.lookupOrThrow(net.minecraft.core.registries.Registries.NOISE), getSeed());
+        }
+
+        final java.util.List<org.bukkit.block.Biome> possibleBiomes = CraftWorldInfo.this.vanillaChunkGenerator.getBiomeSource().possibleBiomes().stream()
+            .map(biome -> org.bukkit.craftbukkit.block.CraftBiome.minecraftHolderToBukkit(biome))
+            .toList();
+        return new org.bukkit.generator.BiomeProvider() {
+            @Override
+            public org.bukkit.block.Biome getBiome(final WorldInfo worldInfo, final int x, final int y, final int z) {
+                return org.bukkit.craftbukkit.block.CraftBiome.minecraftHolderToBukkit(
+                    CraftWorldInfo.this.vanillaChunkGenerator.getBiomeSource().getNoiseBiome(x >> 2, y >> 2, z >> 2, randomState.sampler()));
+            }
+
+            @Override
+            public java.util.List<org.bukkit.block.Biome> getBiomes(final org.bukkit.generator.WorldInfo worldInfo) {
+                return possibleBiomes;
+            }
+        };
+    }
+    // Paper end
 }

paper-server/src/main/java/org/bukkit/craftbukkit/generator/CustomWorldChunkManager.java

@@ -31,7 +31,11 @@ public class CustomWorldChunkManager extends BiomeSource {
         return biomeBases;
     }
 
-    public CustomWorldChunkManager(WorldInfo worldInfo, BiomeProvider biomeProvider, Registry<net.minecraft.world.level.biome.Biome> registry) {
+    // Paper start - add vanillaBiomeProvider
+    public final BiomeSource vanillaBiomeSource;
+    public CustomWorldChunkManager(WorldInfo worldInfo, BiomeProvider biomeProvider, Registry<net.minecraft.world.level.biome.Biome> registry, BiomeSource vanillaBiomeSource) {
+        this.vanillaBiomeSource = vanillaBiomeSource;
+        // Paper end - add vanillaBiomeProvider
         this.worldInfo = worldInfo;
         this.biomeProvider = biomeProvider;
         this.registry = registry;