Move flat bedrock generator to file patches

feature-patches/1042-Flat-bedrock-generator-settings.patch

@@ -1,292 +0,0 @@
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Byteflux <byte@byteflux.net>
-Date: Wed, 2 Mar 2016 02:17:54 -0600
-Subject: [PATCH] Flat bedrock generator settings
-
-== AT ==
-public net.minecraft.world.level.levelgen.SurfaceRules$Condition
-public net.minecraft.world.level.levelgen.SurfaceRules$Context
-public net.minecraft.world.level.levelgen.SurfaceRules$Context blockX
-public net.minecraft.world.level.levelgen.SurfaceRules$Context blockY
-public net.minecraft.world.level.levelgen.SurfaceRules$Context blockZ
-public net.minecraft.world.level.levelgen.SurfaceRules$Context context
-public net.minecraft.world.level.levelgen.SurfaceRules$Context randomState
-public net.minecraft.world.level.levelgen.SurfaceRules$LazyYCondition
-public net.minecraft.world.level.levelgen.SurfaceRules$LazyCondition
-public net.minecraft.world.level.levelgen.SurfaceRules$VerticalGradientConditionSource
-public net.minecraft.world.level.levelgen.SurfaceRules$SurfaceRule
-
-Co-authored-by: Noah van der Aa <ndvdaa@gmail.com>
-
-diff --git a/src/main/java/io/papermc/paper/world/worldgen/OptionallyFlatBedrockConditionSource.java b/src/main/java/io/papermc/paper/world/worldgen/OptionallyFlatBedrockConditionSource.java
-new file mode 100644
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
---- /dev/null
-+++ b/src/main/java/io/papermc/paper/world/worldgen/OptionallyFlatBedrockConditionSource.java
-@@ -0,0 +0,0 @@
-+package io.papermc.paper.world.worldgen;
-+
-+import com.mojang.serialization.Codec;
-+import com.mojang.serialization.MapCodec;
-+import com.mojang.serialization.codecs.RecordCodecBuilder;
-+import net.minecraft.core.Registry;
-+import net.minecraft.core.registries.BuiltInRegistries;
-+import net.minecraft.core.registries.Registries;
-+import net.minecraft.resources.ResourceKey;
-+import net.minecraft.resources.ResourceLocation;
-+import net.minecraft.util.KeyDispatchDataCodec;
-+import net.minecraft.util.Mth;
-+import net.minecraft.util.RandomSource;
-+import net.minecraft.world.level.levelgen.PositionalRandomFactory;
-+import net.minecraft.world.level.levelgen.SurfaceRules;
-+import net.minecraft.world.level.levelgen.VerticalAnchor;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
-+
-+// Modelled off of SurfaceRules$VerticalGradientConditionSource
-+@DefaultQualifier(NonNull.class)
-+public record OptionallyFlatBedrockConditionSource(ResourceLocation randomName, VerticalAnchor trueAtAndBelow, VerticalAnchor falseAtAndAbove, boolean isRoof) implements SurfaceRules.ConditionSource {
-+
-+    private static final ResourceKey<MapCodec<? extends SurfaceRules.ConditionSource>> CODEC_RESOURCE_KEY = ResourceKey.create(
-+        Registries.MATERIAL_CONDITION,
-+        ResourceLocation.fromNamespaceAndPath(ResourceLocation.PAPER_NAMESPACE, "optionally_flat_bedrock_condition_source")
-+    );
-+    private static final KeyDispatchDataCodec<OptionallyFlatBedrockConditionSource> CODEC = KeyDispatchDataCodec.of(RecordCodecBuilder.mapCodec((instance) -> {
-+        return instance.group(
-+            ResourceLocation.CODEC.fieldOf("random_name").forGetter(OptionallyFlatBedrockConditionSource::randomName),
-+            VerticalAnchor.CODEC.fieldOf("true_at_and_below").forGetter(OptionallyFlatBedrockConditionSource::trueAtAndBelow),
-+            VerticalAnchor.CODEC.fieldOf("false_at_and_above").forGetter(OptionallyFlatBedrockConditionSource::falseAtAndAbove),
-+            Codec.BOOL.fieldOf("is_roof").forGetter(OptionallyFlatBedrockConditionSource::isRoof)
-+        ).apply(instance, OptionallyFlatBedrockConditionSource::new);
-+    }));
-+
-+    public static void bootstrap() {
-+        Registry.register(BuiltInRegistries.MATERIAL_CONDITION, CODEC_RESOURCE_KEY, CODEC.codec());
-+    }
-+
-+    @Override
-+    public KeyDispatchDataCodec<? extends SurfaceRules.ConditionSource> codec() {
-+        return CODEC;
-+    }
-+
-+    @Override
-+    public SurfaceRules.Condition apply(final SurfaceRules.Context context) {
-+        boolean hasFlatBedrock = context.context.getWorld().paperConfig().environment.generateFlatBedrock;
-+        int tempTrueAtAndBelowY = this.trueAtAndBelow().resolveY(context.context);
-+        int tempFalseAtAndAboveY = this.falseAtAndAbove().resolveY(context.context);
-+
-+        int flatYLevel = this.isRoof ? Math.max(tempFalseAtAndAboveY, tempTrueAtAndBelowY) - 1 : Math.min(tempFalseAtAndAboveY, tempTrueAtAndBelowY);
-+        final int trueAtAndBelowY = hasFlatBedrock ? flatYLevel : tempTrueAtAndBelowY;
-+        final int falseAtAndAboveY = hasFlatBedrock ? flatYLevel : tempFalseAtAndAboveY;
-+
-+        final PositionalRandomFactory positionalRandomFactory = context.randomState.getOrCreateRandomFactory(this.randomName());
-+
-+        class VerticalGradientCondition extends SurfaceRules.LazyYCondition {
-+            VerticalGradientCondition(SurfaceRules.Context context) {
-+                super(context);
-+            }
-+
-+            @Override
-+            protected boolean compute() {
-+                int blockY = this.context.blockY;
-+                if (blockY <= trueAtAndBelowY) {
-+                    return true;
-+                } else if (blockY >= falseAtAndAboveY) {
-+                    return false;
-+                } else {
-+                    double d = Mth.map(blockY, trueAtAndBelowY, falseAtAndAboveY, 1.0D, 0.0D);
-+                    RandomSource randomSource = positionalRandomFactory.at(this.context.blockX, blockY, this.context.blockZ);
-+                    return (double)randomSource.nextFloat() < d;
-+                }
-+            }
-+        }
-+
-+        return new VerticalGradientCondition(context);
-+    }
-+}
-diff --git a/src/main/java/net/minecraft/server/Bootstrap.java b/src/main/java/net/minecraft/server/Bootstrap.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/java/net/minecraft/server/Bootstrap.java
-+++ b/src/main/java/net/minecraft/server/Bootstrap.java
-@@ -0,0 +0,0 @@ public class Bootstrap {
-                     CauldronInteraction.bootStrap();
-                     // Paper start
-                     BuiltInRegistries.bootStrap(() -> {
-+                        io.papermc.paper.world.worldgen.OptionallyFlatBedrockConditionSource.bootstrap(); // Paper - Flat bedrock generator settings
-                     });
-                     // Paper end
-                     CreativeModeTabs.validate();
-diff --git a/src/main/java/net/minecraft/world/level/levelgen/NoiseBasedChunkGenerator.java b/src/main/java/net/minecraft/world/level/levelgen/NoiseBasedChunkGenerator.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/java/net/minecraft/world/level/levelgen/NoiseBasedChunkGenerator.java
-+++ b/src/main/java/net/minecraft/world/level/levelgen/NoiseBasedChunkGenerator.java
-@@ -0,0 +0,0 @@ public final class NoiseBasedChunkGenerator extends ChunkGenerator {
-     @Override
-     public void buildSurface(WorldGenRegion region, StructureManager structures, RandomState noiseConfig, ChunkAccess chunk) {
-         if (!SharedConstants.debugVoidTerrain(chunk.getPos())) {
--            WorldGenerationContext worldgenerationcontext = new WorldGenerationContext(this, region);
-+            WorldGenerationContext worldgenerationcontext = new WorldGenerationContext(this, region, region.getMinecraftWorld()); // Paper - Flat bedrock generator settings
- 
-             this.buildSurface(chunk, worldgenerationcontext, noiseConfig, structures, region.getBiomeManager(), region.registryAccess().lookupOrThrow(Registries.BIOME), Blender.of(region));
-         }
-@@ -0,0 +0,0 @@ public final class NoiseBasedChunkGenerator extends ChunkGenerator {
-             return this.createNoiseChunk(ichunkaccess1, structureAccessor, Blender.of(chunkRegion), noiseConfig);
-         });
-         Aquifer aquifer = noisechunk.aquifer();
--        CarvingContext carvingcontext = new CarvingContext(this, chunkRegion.registryAccess(), chunk.getHeightAccessorForGeneration(), noisechunk, noiseConfig, ((NoiseGeneratorSettings) this.settings.value()).surfaceRule());
-+        CarvingContext carvingcontext = new CarvingContext(this, chunkRegion.registryAccess(), chunk.getHeightAccessorForGeneration(), noisechunk, noiseConfig, ((NoiseGeneratorSettings) this.settings.value()).surfaceRule(), chunkRegion.getMinecraftWorld()); // Paper - Flat bedrock generator settings
-         CarvingMask carvingmask = ((ProtoChunk) chunk).getOrCreateCarvingMask();
- 
-         for (int j = -8; j <= 8; ++j) {
-diff --git a/src/main/java/net/minecraft/world/level/levelgen/WorldGenerationContext.java b/src/main/java/net/minecraft/world/level/levelgen/WorldGenerationContext.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/java/net/minecraft/world/level/levelgen/WorldGenerationContext.java
-+++ b/src/main/java/net/minecraft/world/level/levelgen/WorldGenerationContext.java
-@@ -0,0 +0,0 @@ import net.minecraft.world.level.chunk.ChunkGenerator;
- public class WorldGenerationContext {
-     private final int minY;
-     private final int height;
-+    private final @javax.annotation.Nullable net.minecraft.world.level.Level level; // Paper - Flat bedrock generator settings
- 
--    public WorldGenerationContext(ChunkGenerator generator, LevelHeightAccessor world) {
-+    public WorldGenerationContext(ChunkGenerator generator, LevelHeightAccessor world) { this(generator, world, null); } // Paper - Flat bedrock generator settings
-+    public WorldGenerationContext(ChunkGenerator generator, LevelHeightAccessor world, @org.jetbrains.annotations.Nullable net.minecraft.world.level.Level level) { // Paper - Flat bedrock generator settings
-         this.minY = Math.max(world.getMinY(), generator.getMinY());
-         this.height = Math.min(world.getHeight(), generator.getGenDepth());
-+        this.level = level; // Paper - Flat bedrock generator settings
-     }
- 
-     public int getMinGenY() {
-@@ -0,0 +0,0 @@ public class WorldGenerationContext {
-     public int getGenDepth() {
-         return this.height;
-     }
-+
-+    // Paper start - Flat bedrock generator settings
-+    public net.minecraft.world.level.Level getWorld() {
-+        if (this.level == null) {
-+            throw new NullPointerException("WorldGenerationContext was initialized without a Level, but WorldGenerationContext#getWorld was called");
-+        }
-+        return this.level;
-+    }
-+    // Paper end - Flat bedrock generator settings
- }
-diff --git a/src/main/java/net/minecraft/world/level/levelgen/carver/CarvingContext.java b/src/main/java/net/minecraft/world/level/levelgen/carver/CarvingContext.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/java/net/minecraft/world/level/levelgen/carver/CarvingContext.java
-+++ b/src/main/java/net/minecraft/world/level/levelgen/carver/CarvingContext.java
-@@ -0,0 +0,0 @@ public class CarvingContext extends WorldGenerationContext {
-         LevelHeightAccessor heightLimitView,
-         NoiseChunk chunkNoiseSampler,
-         RandomState noiseConfig,
--        SurfaceRules.RuleSource materialRule
-+        SurfaceRules.RuleSource materialRule, @javax.annotation.Nullable net.minecraft.world.level.Level level  // Paper - Flat bedrock generator settings
-     ) {
--        super(noiseChunkGenerator, heightLimitView);
-+        super(noiseChunkGenerator, heightLimitView, level); // Paper - Flat bedrock generator settings
-         this.registryAccess = registryManager;
-         this.noiseChunk = chunkNoiseSampler;
-         this.randomState = noiseConfig;
-diff --git a/src/main/java/net/minecraft/world/level/levelgen/placement/PlacementContext.java b/src/main/java/net/minecraft/world/level/levelgen/placement/PlacementContext.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/java/net/minecraft/world/level/levelgen/placement/PlacementContext.java
-+++ b/src/main/java/net/minecraft/world/level/levelgen/placement/PlacementContext.java
-@@ -0,0 +0,0 @@ public class PlacementContext extends WorldGenerationContext {
-     private final Optional<PlacedFeature> topFeature;
- 
-     public PlacementContext(WorldGenLevel world, ChunkGenerator generator, Optional<PlacedFeature> placedFeature) {
--        super(generator, world);
-+        super(generator, world, world.getLevel()); // Paper - Flat bedrock generator settings
-         this.level = world;
-         this.generator = generator;
-         this.topFeature = placedFeature;
-diff --git a/src/main/resources/data/minecraft/worldgen/noise_settings/amplified.json b/src/main/resources/data/minecraft/worldgen/noise_settings/amplified.json
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/resources/data/minecraft/worldgen/noise_settings/amplified.json
-+++ b/src/main/resources/data/minecraft/worldgen/noise_settings/amplified.json
-@@ -0,0 +0,0 @@
-       {
-         "type": "minecraft:condition",
-         "if_true": {
--          "type": "minecraft:vertical_gradient",
-+          "type": "paper:optionally_flat_bedrock_condition_source",
-+          "is_roof": false,
-           "false_at_and_above": {
-             "above_bottom": 5
-           },
-diff --git a/src/main/resources/data/minecraft/worldgen/noise_settings/caves.json b/src/main/resources/data/minecraft/worldgen/noise_settings/caves.json
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/resources/data/minecraft/worldgen/noise_settings/caves.json
-+++ b/src/main/resources/data/minecraft/worldgen/noise_settings/caves.json
-@@ -0,0 +0,0 @@
-         "if_true": {
-           "type": "minecraft:not",
-           "invert": {
--            "type": "minecraft:vertical_gradient",
-+            "type": "paper:optionally_flat_bedrock_condition_source",
-+            "is_roof": true,
-             "false_at_and_above": {
-               "below_top": 0
-             },
-@@ -0,0 +0,0 @@
-       {
-         "type": "minecraft:condition",
-         "if_true": {
--          "type": "minecraft:vertical_gradient",
-+          "type": "paper:optionally_flat_bedrock_condition_source",
-+          "is_roof": false,
-           "false_at_and_above": {
-             "above_bottom": 5
-           },
-diff --git a/src/main/resources/data/minecraft/worldgen/noise_settings/large_biomes.json b/src/main/resources/data/minecraft/worldgen/noise_settings/large_biomes.json
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/resources/data/minecraft/worldgen/noise_settings/large_biomes.json
-+++ b/src/main/resources/data/minecraft/worldgen/noise_settings/large_biomes.json
-@@ -0,0 +0,0 @@
-       {
-         "type": "minecraft:condition",
-         "if_true": {
--          "type": "minecraft:vertical_gradient",
-+          "type": "paper:optionally_flat_bedrock_condition_source",
-+          "is_roof": false,
-           "false_at_and_above": {
-             "above_bottom": 5
-           },
-diff --git a/src/main/resources/data/minecraft/worldgen/noise_settings/nether.json b/src/main/resources/data/minecraft/worldgen/noise_settings/nether.json
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/resources/data/minecraft/worldgen/noise_settings/nether.json
-+++ b/src/main/resources/data/minecraft/worldgen/noise_settings/nether.json
-@@ -0,0 +0,0 @@
-       {
-         "type": "minecraft:condition",
-         "if_true": {
--          "type": "minecraft:vertical_gradient",
-+          "type": "paper:optionally_flat_bedrock_condition_source",
-+          "is_roof": false,
-           "false_at_and_above": {
-             "above_bottom": 5
-           },
-@@ -0,0 +0,0 @@
-         "if_true": {
-           "type": "minecraft:not",
-           "invert": {
--            "type": "minecraft:vertical_gradient",
-+            "type": "paper:optionally_flat_bedrock_condition_source",
-+            "is_roof": true,
-             "false_at_and_above": {
-               "below_top": 0
-             },
-diff --git a/src/main/resources/data/minecraft/worldgen/noise_settings/overworld.json b/src/main/resources/data/minecraft/worldgen/noise_settings/overworld.json
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/resources/data/minecraft/worldgen/noise_settings/overworld.json
-+++ b/src/main/resources/data/minecraft/worldgen/noise_settings/overworld.json
-@@ -0,0 +0,0 @@
-       {
-         "type": "minecraft:condition",
-         "if_true": {
--          "type": "minecraft:vertical_gradient",
-+          "type": "paper:optionally_flat_bedrock_condition_source",
-+          "is_roof": false,
-           "false_at_and_above": {
-             "above_bottom": 5
-           },

paper-server/patches/resources/data/minecraft/worldgen/noise_settings/amplified.json.patch

@@ -0,0 +1,12 @@
+--- a/data/minecraft/worldgen/noise_settings/amplified.json
++++ b/data/minecraft/worldgen/noise_settings/amplified.json
+@@ -389,7 +_,8 @@
+       {
+         "type": "minecraft:condition",
+         "if_true": {
+-          "type": "minecraft:vertical_gradient",
++          "type": "paper:optionally_flat_bedrock_condition_source",
++          "is_roof": false,
+           "false_at_and_above": {
+             "above_bottom": 5
+           },

paper-server/patches/resources/data/minecraft/worldgen/noise_settings/caves.json.patch

@@ -0,0 +1,22 @@
+--- a/data/minecraft/worldgen/noise_settings/caves.json
++++ b/data/minecraft/worldgen/noise_settings/caves.json
+@@ -110,7 +_,8 @@
+         "if_true": {
+           "type": "minecraft:not",
+           "invert": {
+-            "type": "minecraft:vertical_gradient",
++            "type": "paper:optionally_flat_bedrock_condition_source",
++            "is_roof": true,
+             "false_at_and_above": {
+               "below_top": 0
+             },
+@@ -130,7 +_,8 @@
+       {
+         "type": "minecraft:condition",
+         "if_true": {
+-          "type": "minecraft:vertical_gradient",
++          "type": "paper:optionally_flat_bedrock_condition_source",
++          "is_roof": false,
+           "false_at_and_above": {
+             "above_bottom": 5
+           },

paper-server/patches/resources/data/minecraft/worldgen/noise_settings/large_biomes.json.patch

@@ -0,0 +1,12 @@
+--- a/data/minecraft/worldgen/noise_settings/large_biomes.json
++++ b/data/minecraft/worldgen/noise_settings/large_biomes.json
+@@ -389,7 +_,8 @@
+       {
+         "type": "minecraft:condition",
+         "if_true": {
+-          "type": "minecraft:vertical_gradient",
++          "type": "paper:optionally_flat_bedrock_condition_source",
++          "is_roof": false,
+           "false_at_and_above": {
+             "above_bottom": 5
+           },

paper-server/patches/resources/data/minecraft/worldgen/noise_settings/nether.json.patch

@@ -0,0 +1,22 @@
+--- a/data/minecraft/worldgen/noise_settings/nether.json
++++ b/data/minecraft/worldgen/noise_settings/nether.json
+@@ -108,7 +_,8 @@
+       {
+         "type": "minecraft:condition",
+         "if_true": {
+-          "type": "minecraft:vertical_gradient",
++          "type": "paper:optionally_flat_bedrock_condition_source",
++          "is_roof": false,
+           "false_at_and_above": {
+             "above_bottom": 5
+           },
+@@ -129,7 +_,8 @@
+         "if_true": {
+           "type": "minecraft:not",
+           "invert": {
+-            "type": "minecraft:vertical_gradient",
++            "type": "paper:optionally_flat_bedrock_condition_source",
++            "is_roof": true,
+             "false_at_and_above": {
+               "below_top": 0
+             },

paper-server/patches/resources/data/minecraft/worldgen/noise_settings/overworld.json.patch

@@ -0,0 +1,12 @@
+--- a/data/minecraft/worldgen/noise_settings/overworld.json
++++ b/data/minecraft/worldgen/noise_settings/overworld.json
+@@ -389,7 +_,8 @@
+       {
+         "type": "minecraft:condition",
+         "if_true": {
+-          "type": "minecraft:vertical_gradient",
++          "type": "paper:optionally_flat_bedrock_condition_source",
++          "is_roof": false,
+           "false_at_and_above": {
+             "above_bottom": 5
+           },

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

@@ -8,13 +8,14 @@
              if (BuiltInRegistries.REGISTRY.keySet().isEmpty()) {
                  throw new IllegalStateException("Unable to load registries");
              } else {
-@@ -54,11 +_,77 @@
+@@ -54,11 +_,78 @@
                      EntitySelectorOptions.bootStrap();
                      DispenseItemBehavior.bootStrap();
                      CauldronInteraction.bootStrap();
 -                    BuiltInRegistries.bootStrap();
 +                    // Paper start
 +                    BuiltInRegistries.bootStrap(() -> {
++                        io.papermc.paper.world.worldgen.OptionallyFlatBedrockConditionSource.bootstrap(); // Paper - Flat bedrock generator settings
 +                    });
 +                    // Paper end
                      CreativeModeTabs.validate();

paper-server/patches/sources/net/minecraft/world/level/levelgen/NoiseBasedChunkGenerator.java.patch

@@ -5,3 +5,21 @@
  package net.minecraft.world.level.levelgen;
  
  import com.google.common.annotations.VisibleForTesting;
+@@ -218,7 +_,7 @@
+     @Override
+     public void buildSurface(WorldGenRegion level, StructureManager structureManager, RandomState random, ChunkAccess chunk) {
+         if (!SharedConstants.debugVoidTerrain(chunk.getPos())) {
+-            WorldGenerationContext worldGenerationContext = new WorldGenerationContext(this, level);
++            WorldGenerationContext worldGenerationContext = new WorldGenerationContext(this, level, level.getMinecraftWorld()); // Paper - Flat bedrock generator settings
+             this.buildSurface(
+                 chunk,
+                 worldGenerationContext,
+@@ -260,7 +_,7 @@
+         NoiseChunk noiseChunk = chunk.getOrCreateNoiseChunk(chunkAccess -> this.createNoiseChunk(chunkAccess, structureManager, Blender.of(level), random));
+         Aquifer aquifer = noiseChunk.aquifer();
+         CarvingContext carvingContext = new CarvingContext(
+-            this, level.registryAccess(), chunk.getHeightAccessorForGeneration(), noiseChunk, random, this.settings.value().surfaceRule()
++            this, level.registryAccess(), chunk.getHeightAccessorForGeneration(), noiseChunk, random, this.settings.value().surfaceRule(), level.getMinecraftWorld() // Paper - Flat bedrock generator settings
+         );
+         CarvingMask carvingMask = ((ProtoChunk)chunk).getOrCreateCarvingMask();
+ 

paper-server/patches/sources/net/minecraft/world/level/levelgen/WorldGenerationContext.java.patch

@@ -0,0 +1,32 @@
+--- a/net/minecraft/world/level/levelgen/WorldGenerationContext.java
++++ b/net/minecraft/world/level/levelgen/WorldGenerationContext.java
+@@ -6,8 +_,15 @@
+ public class WorldGenerationContext {
+     private final int minY;
+     private final int height;
++    // Paper start - Flat bedrock generator settings
++    private final @javax.annotation.Nullable net.minecraft.world.level.Level serverLevel;
+ 
+     public WorldGenerationContext(ChunkGenerator generator, LevelHeightAccessor level) {
++        this(generator, level, null);
++    }
++    public WorldGenerationContext(ChunkGenerator generator, LevelHeightAccessor level, net.minecraft.world.level.Level serverLevel) {
++        this.serverLevel = serverLevel;
++        // Paper end - Flat bedrock generator settings
+         this.minY = Math.max(level.getMinY(), generator.getMinY());
+         this.height = Math.min(level.getHeight(), generator.getGenDepth());
+     }
+@@ -19,4 +_,13 @@
+     public int getGenDepth() {
+         return this.height;
+     }
++
++    // Paper start - Flat bedrock generator settings
++    public net.minecraft.world.level.Level level() {
++        if (this.serverLevel == null) {
++            throw new NullPointerException("WorldGenerationContext was initialized without a Level, but WorldGenerationContext#level was called");
++        }
++        return this.serverLevel;
++    }
++    // Paper end - Flat bedrock generator settings
+ }

paper-server/patches/sources/net/minecraft/world/level/levelgen/carver/CarvingContext.java.patch

@@ -0,0 +1,14 @@
+--- a/net/minecraft/world/level/levelgen/carver/CarvingContext.java
++++ b/net/minecraft/world/level/levelgen/carver/CarvingContext.java
+@@ -27,9 +_,9 @@
+         LevelHeightAccessor level,
+         NoiseChunk noiseChunk,
+         RandomState randomState,
+-        SurfaceRules.RuleSource surfaceRule
++        SurfaceRules.RuleSource surfaceRule, @javax.annotation.Nullable net.minecraft.world.level.Level serverLevel  // Paper - Flat bedrock generator settings
+     ) {
+-        super(generator, level);
++        super(generator, level, serverLevel); // Paper - Flat bedrock generator settings
+         this.registryAccess = registryAccess;
+         this.noiseChunk = noiseChunk;
+         this.randomState = randomState;

paper-server/patches/sources/net/minecraft/world/level/levelgen/placement/PlacementContext.java.patch

@@ -0,0 +1,11 @@
+--- a/net/minecraft/world/level/levelgen/placement/PlacementContext.java
++++ b/net/minecraft/world/level/levelgen/placement/PlacementContext.java
+@@ -17,7 +_,7 @@
+     private final Optional<PlacedFeature> topFeature;
+ 
+     public PlacementContext(WorldGenLevel level, ChunkGenerator generator, Optional<PlacedFeature> topFeature) {
+-        super(generator, level);
++        super(generator, level, level.getLevel()); // Paper - Flat bedrock generator settings
+         this.level = level;
+         this.generator = generator;
+         this.topFeature = topFeature;

paper-server/src/main/java/io/papermc/paper/world/worldgen/OptionallyFlatBedrockConditionSource.java

@@ -0,0 +1,81 @@
+package io.papermc.paper.world.worldgen;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.MapCodec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.util.KeyDispatchDataCodec;
+import net.minecraft.util.Mth;
+import net.minecraft.util.RandomSource;
+import net.minecraft.world.level.levelgen.PositionalRandomFactory;
+import net.minecraft.world.level.levelgen.SurfaceRules;
+import net.minecraft.world.level.levelgen.VerticalAnchor;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+// Modelled off of SurfaceRules$VerticalGradientConditionSource
+// Flat bedrock generator settings
+@DefaultQualifier(NonNull.class)
+public record OptionallyFlatBedrockConditionSource(ResourceLocation randomName, VerticalAnchor trueAtAndBelow, VerticalAnchor falseAtAndAbove, boolean isRoof) implements SurfaceRules.ConditionSource {
+
+    private static final ResourceKey<MapCodec<? extends SurfaceRules.ConditionSource>> CODEC_RESOURCE_KEY = ResourceKey.create(
+        Registries.MATERIAL_CONDITION,
+        ResourceLocation.fromNamespaceAndPath(ResourceLocation.PAPER_NAMESPACE, "optionally_flat_bedrock_condition_source")
+    );
+    private static final KeyDispatchDataCodec<OptionallyFlatBedrockConditionSource> CODEC = KeyDispatchDataCodec.of(RecordCodecBuilder.mapCodec((instance) -> {
+        return instance.group(
+            ResourceLocation.CODEC.fieldOf("random_name").forGetter(OptionallyFlatBedrockConditionSource::randomName),
+            VerticalAnchor.CODEC.fieldOf("true_at_and_below").forGetter(OptionallyFlatBedrockConditionSource::trueAtAndBelow),
+            VerticalAnchor.CODEC.fieldOf("false_at_and_above").forGetter(OptionallyFlatBedrockConditionSource::falseAtAndAbove),
+            Codec.BOOL.fieldOf("is_roof").forGetter(OptionallyFlatBedrockConditionSource::isRoof)
+        ).apply(instance, OptionallyFlatBedrockConditionSource::new);
+    }));
+
+    public static void bootstrap() {
+        Registry.register(BuiltInRegistries.MATERIAL_CONDITION, CODEC_RESOURCE_KEY, CODEC.codec());
+    }
+
+    @Override
+    public KeyDispatchDataCodec<? extends SurfaceRules.ConditionSource> codec() {
+        return CODEC;
+    }
+
+    @Override
+    public SurfaceRules.Condition apply(final SurfaceRules.Context context) {
+        boolean hasFlatBedrock = context.context.level().paperConfig().environment.generateFlatBedrock;
+        int tempTrueAtAndBelowY = this.trueAtAndBelow().resolveY(context.context);
+        int tempFalseAtAndAboveY = this.falseAtAndAbove().resolveY(context.context);
+
+        int flatYLevel = this.isRoof ? Math.max(tempFalseAtAndAboveY, tempTrueAtAndBelowY) - 1 : Math.min(tempFalseAtAndAboveY, tempTrueAtAndBelowY);
+        final int trueAtAndBelowY = hasFlatBedrock ? flatYLevel : tempTrueAtAndBelowY;
+        final int falseAtAndAboveY = hasFlatBedrock ? flatYLevel : tempFalseAtAndAboveY;
+
+        final PositionalRandomFactory positionalRandomFactory = context.randomState.getOrCreateRandomFactory(this.randomName());
+
+        class VerticalGradientCondition extends SurfaceRules.LazyYCondition {
+            VerticalGradientCondition(SurfaceRules.Context context) {
+                super(context);
+            }
+
+            @Override
+            protected boolean compute() {
+                int blockY = this.context.blockY;
+                if (blockY <= trueAtAndBelowY) {
+                    return true;
+                } else if (blockY >= falseAtAndAboveY) {
+                    return false;
+                } else {
+                    double d = Mth.map(blockY, trueAtAndBelowY, falseAtAndAboveY, 1.0D, 0.0D);
+                    RandomSource randomSource = positionalRandomFactory.at(this.context.blockX, blockY, this.context.blockZ);
+                    return (double)randomSource.nextFloat() < d;
+                }
+            }
+        }
+
+        return new VerticalGradientCondition(context);
+    }
+}