Add AT entries for DimensionSettings to make them easier for mods to work with (#7817)

src/main/resources/META-INF/accesstransformer.cfg

@@ -325,6 +325,8 @@ public net.minecraft.world.chunk.ChunkStatus <init>(Ljava/lang/String;Lnet/minec
 private-f net.minecraft.world.gen.DebugChunkGenerator field_177462_b #GRID_WIDTH
 private-f net.minecraft.world.gen.DebugChunkGenerator field_177464_a #ALL_VALID_STATES
 private-f net.minecraft.world.gen.DebugChunkGenerator field_181039_c #GRID_HEIGHT
+public net.minecraft.world.gen.DimensionSettings <init>(Lnet/minecraft/world/gen/settings/DimensionStructuresSettings;Lnet/minecraft/world/gen/settings/NoiseSettings;Lnet/minecraft/block/BlockState;Lnet/minecraft/block/BlockState;IIIZ)V # constructor
+public net.minecraft.world.gen.DimensionSettings func_236120_h_()Z # isMobGenerationDisabled
 public net.minecraft.world.gen.blockplacer.BlockPlacerType <init>(Lcom/mojang/serialization/Codec;)V # constructor
 public net.minecraft.world.gen.blockstateprovider.BlockStateProviderType <init>(Lcom/mojang/serialization/Codec;)V # constructor
 public net.minecraft.world.gen.foliageplacer.FoliagePlacerType <init>(Lcom/mojang/serialization/Codec;)V # constructor

src/test/java/net/minecraftforge/debug/world/DimensionSettingsTest.java

@@ -0,0 +1,100 @@
+package net.minecraftforge.debug.world;
+
+import net.minecraft.util.ResourceLocation;
+import net.minecraft.util.registry.WorldGenRegistries;
+import net.minecraft.world.gen.DimensionSettings;
+import net.minecraft.world.gen.feature.structure.Structure;
+import net.minecraft.world.gen.settings.DimensionStructuresSettings;
+import net.minecraft.world.gen.settings.StructureSeparationSettings;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.event.lifecycle.FMLCommonSetupEvent;
+import net.minecraftforge.fml.event.lifecycle.FMLLoadCompleteEvent;
+import net.minecraftforge.fml.javafmlmod.FMLJavaModLoadingContext;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import java.util.HashMap;
+import java.util.Optional;
+
+/**
+ * To see the effects of this test mod you must create a new world then teleport to the custom
+ * dimension (use: /execute in dimension_settings_test:test_overworld run tp @s ...).
+ *
+ * You should observe that the only structure that generates in the dimension is the ruined portal
+ * and it should do so very frequently.
+ *
+ * Note: This mod adds a data asset located at:
+ * /data/dimension_settings_test/dimension/test_overworld.json
+ */
+@Mod(DimensionSettingsTest.MODID)
+public class DimensionSettingsTest {
+    public static final String MODID = "dimension_settings_test";
+    public static final ResourceLocation TEST_OVERWORLD = new ResourceLocation(MODID, "test_overworld");
+
+    private static final Logger LOGGER = LogManager.getLogger();
+
+    public DimensionSettingsTest()
+    {
+        FMLJavaModLoadingContext.get().getModEventBus().addListener(this::registerSettings);
+        FMLJavaModLoadingContext.get().getModEventBus().addListener(this::addStructure);
+    }
+
+    /**
+     * Demonstrates how a mod can register custom DimensionSettings which can be referenced from
+     * within a datapack dimension config whilst being discoverable for other mods to add to and
+     * remove structures etc from.
+     */
+    private void registerSettings(FMLCommonSetupEvent event)
+    {
+        event.enqueueWork(() ->
+        {
+            LOGGER.info("Registering custom DimensionSettings for Dimension: {}", TEST_OVERWORLD);
+            DimensionSettings dimensionSettings = createDimensionSettings();
+            WorldGenRegistries.register(WorldGenRegistries.NOISE_GENERATOR_SETTINGS, TEST_OVERWORLD, dimensionSettings);
+        });
+    }
+
+    /**
+     * Demonstrates how a mod could handle adding their structure settings to a specific dimension.
+     */
+    private void addStructure(FMLLoadCompleteEvent event)
+    {
+        event.enqueueWork(() ->
+        {
+            StructureSeparationSettings settings = new StructureSeparationSettings(2, 1, 0);
+
+            WorldGenRegistries.NOISE_GENERATOR_SETTINGS.entrySet().forEach(entry ->
+            {
+                ResourceLocation dimensionName = entry.getKey().location();
+
+                // Example: blacklisting all vanilla dimensions
+                if (dimensionName.getNamespace().equals("minecraft")) return;
+
+                LOGGER.info("Adding Structure: {} to Dimension: {}", Structure.RUINED_PORTAL.getFeatureName(), dimensionName);
+                entry.getValue().structureSettings().structureConfig().put(Structure.RUINED_PORTAL, settings);
+            });
+        });
+    }
+
+    /**
+     * Create a DimensionSettings instance copying all but the structure settings from overworld.
+     */
+    private static DimensionSettings createDimensionSettings()
+    {
+        DimensionSettings overworld = WorldGenRegistries.NOISE_GENERATOR_SETTINGS.getOrThrow(DimensionSettings.OVERWORLD);
+
+        // Make a new DimensionStructuresSettings with no structures
+        DimensionStructuresSettings structures = new DimensionStructuresSettings(Optional.empty(), new HashMap<>());
+
+        // Build a new DimensionSettings copying all the other options from 'overworld'
+        return new DimensionSettings(
+                structures,
+                overworld.noiseSettings(),
+                overworld.getDefaultBlock(),
+                overworld.getDefaultFluid(),
+                overworld.getBedrockRoofPosition(),
+                overworld.getBedrockFloorPosition(),
+                overworld.seaLevel(),
+                overworld.disableMobGeneration());
+    }
+}

src/test/resources/META-INF/mods.toml

@@ -124,7 +124,9 @@ license="LGPL v2.1"
     modId="entity_teleport_event_test"
 [[mods]]
     modId="text_linear_filtering_test"
-[[mods]]
-    modId="player_attack_knockback_test"
 [[mods]]
     modId="custom_tas_test"
+[[mods]]
+    modId="dimension_settings_test"
+[[mods]]
+    modId="player_attack_knockback_test"

src/test/resources/data/dimension_settings_test/dimension/test_overworld.json

@@ -0,0 +1,19 @@
+{
+  "#comment": [
+    "This is an example Dimension showing how it can be configured to use a custom",
+    "DimensionSettings that possess similar generation settings to overworld but",
+    "has independently configurable structure settings.",
+    "",
+    "See the 'settings' field below"
+  ],
+  "type": "minecraft:overworld",
+  "generator": {
+    "type": "minecraft:noise",
+    "seed": 12345,
+    "settings": "dimension_settings_test:test_overworld",
+    "biome_source": {
+      "seed": 12345,
+      "type": "minecraft:vanilla_layered"
+    }
+  }
+}