Whole chunk deletion

src/main/java/com/cyao/FlatMinecraft.java

@@ -1,9 +1,6 @@
 package com.cyao;
 
 import net.fabricmc.api.ModInitializer;
-import net.minecraft.registry.Registries;
-import net.minecraft.registry.Registry;
-import net.minecraft.util.Identifier;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -14,8 +11,5 @@ public class FlatMinecraft implements ModInitializer {
 	@Override
 	public void onInitialize() {
 		LOGGER.info("Initializing mod");
-		Registry.register(Registries.CHUNK_GENERATOR,
-                Identifier.of("flat-minecraft:paper-world"),
-				PaperChunkGenerator.CODEC);
 	}
 }

src/main/java/com/cyao/mixin/ChunkMixin.java

@@ -0,0 +1,51 @@
+package com.cyao.mixin;
+
+import net.minecraft.block.Block;
+import net.minecraft.block.BlockState;
+import net.minecraft.block.Blocks;
+import net.minecraft.registry.entry.RegistryEntry;
+import net.minecraft.util.collection.BoundedRegionArray;
+import net.minecraft.util.collection.PackedIntegerArray;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.ChunkPos;
+import net.minecraft.util.math.MathHelper;
+import net.minecraft.world.Heightmap;
+import net.minecraft.world.biome.Biome;
+import net.minecraft.world.chunk.*;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+
+@Mixin(ChunkGenerating.class)
+public class ChunkMixin {
+    @Inject(method = "initializeLight", at = @At("HEAD"))
+    private static void getInitializeLightingFuture(ChunkGenerationContext context, ChunkGenerationStep step, BoundedRegionArray<AbstractChunkHolder> chunks, Chunk chunk, CallbackInfoReturnable<CompletableFuture<Chunk>> cir) {
+        BlockPos spawn = context.world().getLevelProperties().getSpawnPos();
+
+        ChunkPos pos = chunk.getPos();
+        if ((pos.x < 1874999 && pos.x > -1875000 && pos.z < 1874999 && pos.z > -1875000) &&
+                (pos.z * 16 > spawn.getZ() || (pos.z + 1) * 16 < spawn.getZ())) {
+            ChunkSection[] sections = chunk.getSectionArray();
+            for (int i = 0; i < sections.length; i++) {
+                ChunkSection chunkSection = sections[i];
+                PalettedContainer<BlockState> blockStateContainer = new PalettedContainer<>(Block.STATE_IDS, Blocks.AIR.getDefaultState(), PalettedContainer.PaletteProvider.BLOCK_STATE);
+                ReadableContainer<RegistryEntry<Biome>> biomeContainer = chunkSection.getBiomeContainer();
+                sections[i] = new ChunkSection(blockStateContainer, biomeContainer);
+            }
+
+            for (BlockPos bePos : chunk.getBlockEntityPositions()) {
+                chunk.removeBlockEntity(bePos);
+            }
+
+            int elementBits = MathHelper.ceilLog2(chunk.getHeight() + 1);
+            long[] emptyHeightmap = new PackedIntegerArray(elementBits, 256).getData();
+            for (Map.Entry<Heightmap.Type, Heightmap> entry : chunk.getHeightmaps()) {
+                entry.getValue().setTo(chunk, entry.getKey(), emptyHeightmap);
+            }
+        }
+    }
+}