flatWorldStructureSpawning

src/main/java/carpet/mixins/FlatChunkGeneratorMixin.java

@@ -0,0 +1,58 @@
+package carpet.mixins;
+
+import carpet.settings.CarpetSettings;
+import net.minecraft.entity.EntityCategory;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.IWorld;
+import net.minecraft.world.biome.Biome;
+import net.minecraft.world.biome.source.BiomeSource;
+import net.minecraft.world.gen.chunk.ChunkGenerator;
+import net.minecraft.world.gen.chunk.FlatChunkGenerator;
+import net.minecraft.world.gen.chunk.FlatChunkGeneratorConfig;
+import net.minecraft.world.gen.feature.Feature;
+import org.spongepowered.asm.mixin.Mixin;
+
+import java.util.List;
+
+@Mixin(FlatChunkGenerator.class)
+public abstract class FlatChunkGeneratorMixin extends ChunkGenerator<FlatChunkGeneratorConfig>
+{
+    public FlatChunkGeneratorMixin(IWorld iWorld, BiomeSource biome, FlatChunkGeneratorConfig chunkGeneratorConfig)
+    {
+        super(iWorld, biome, chunkGeneratorConfig);
+    }
+    
+    @Override
+    public List<Biome.SpawnEntry> getEntitySpawnList(EntityCategory category, BlockPos pos)
+    {
+        if (CarpetSettings.flatWorldStructureSpawning)
+        {
+            if (Feature.SWAMP_HUT.method_14029(this.world, pos))
+            {
+                if (category == EntityCategory.MONSTER)
+                {
+                    return Feature.SWAMP_HUT.getMonsterSpawns();
+                }
+        
+                if (category == EntityCategory.CREATURE)
+                {
+                    return Feature.SWAMP_HUT.getCreatureSpawns();
+                }
+            }
+            else if (category == EntityCategory.MONSTER)
+            {
+                if (Feature.PILLAGER_OUTPOST.isApproximatelyInsideStructure(this.world, pos))
+                {
+                    return Feature.PILLAGER_OUTPOST.getMonsterSpawns();
+                }
+        
+                if (Feature.OCEAN_MONUMENT.isApproximatelyInsideStructure(this.world, pos))
+                {
+                    return Feature.OCEAN_MONUMENT.getMonsterSpawns();
+                }
+            }
+        }
+        
+        return super.getEntitySpawnList(category, pos);
+    }
+}

src/main/java/carpet/settings/CarpetSettings.java

@@ -445,4 +445,10 @@ public class CarpetSettings
             category = BUGFIX
     )
     public static boolean horseWanderingFix = false;
+    
+    @Rule(
+            desc = "Allows structure mobs to spawn in flat worlds",
+            category = {EXPERIMENTAL, CREATIVE}
+    )
+    public static boolean flatWorldStructureSpawning = false;
 }

src/main/resources/carpet.mixins.json

@@ -67,6 +67,7 @@
     "PlayerEntity_parrotMixin",
     "SaplingBlockMixin",
     "EntityMixin",
+    "FlatChunkGeneratorMixin",
 
     "GuardianEntityMixin",
     "DesertPyramidFeatureMixin",