fix: ghost mushroom attempt 3

Related to #336

Author: ishland

c2me-fixes-worldgen-vanilla-bugs/src/main/java/com/ishland/c2me/fixes/worldgen/vanilla_bugs/MixinPlugin.java

@@ -0,0 +1,17 @@
+package com.ishland.c2me.fixes.worldgen.vanilla_bugs;
+
+import com.ishland.c2me.base.common.ModuleMixinPlugin;
+import com.ishland.c2me.fixes.worldgen.vanilla_bugs.common.Config;
+
+public class MixinPlugin extends ModuleMixinPlugin {
+
+    @Override
+    public boolean shouldApplyMixin(String targetClassName, String mixinClassName) {
+        if (!super.shouldApplyMixin(targetClassName, mixinClassName)) return false;
+
+        if (mixinClassName.startsWith("com.ishland.c2me.fixes.worldgen.vanilla_bugs.mixin.mc_276863."))
+            return Config.suppressGhostMushrooms;
+
+        return true;
+    }
+}

c2me-fixes-worldgen-vanilla-bugs/src/main/java/com/ishland/c2me/fixes/worldgen/vanilla_bugs/ModuleEntryPoint.java

@@ -1,7 +1,13 @@
 package com.ishland.c2me.fixes.worldgen.vanilla_bugs;
 
+import com.ishland.c2me.fixes.worldgen.vanilla_bugs.common.Config;
+
 public class ModuleEntryPoint {
 
     private static final boolean enabled = true;
 
+    static {
+        Config.init();
+    }
+
 }

c2me-fixes-worldgen-vanilla-bugs/src/main/java/com/ishland/c2me/fixes/worldgen/vanilla_bugs/common/Config.java

@@ -0,0 +1,21 @@
+package com.ishland.c2me.fixes.worldgen.vanilla_bugs.common;
+
+import com.ishland.c2me.base.common.config.ConfigSystem;
+
+public class Config {
+
+    public static final boolean suppressGhostMushrooms = new ConfigSystem.ConfigAccessor()
+            .key("fixes.suppressGhostMushrooms")
+            .comment("""
+                    This option workarounds MC-276863, a bug that makes mushrooms appear in non-postprocessed chunks
+                    This bug is amplified with notickvd as it exposes non-postprocessed chunks to players
+                    
+                    This should not affect other worldgen behavior and game mechanics in general
+                    """)
+            .getBoolean(true, false);
+
+    public static void init() {
+        // intentionally empty
+    }
+
+}

c2me-fixes-worldgen-vanilla-bugs/src/main/java/com/ishland/c2me/fixes/worldgen/vanilla_bugs/mixin/mc_276863/MixinChunkGenerating.java

@@ -0,0 +1,57 @@
+package com.ishland.c2me.fixes.worldgen.vanilla_bugs.mixin.mc_276863;
+
+import com.llamalad7.mixinextras.injector.ModifyReturnValue;
+import it.unimi.dsi.fastutil.shorts.ShortList;
+import it.unimi.dsi.fastutil.shorts.ShortListIterator;
+import net.minecraft.block.Block;
+import net.minecraft.block.BlockState;
+import net.minecraft.block.Blocks;
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.collection.BoundedRegionArray;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.ChunkPos;
+import net.minecraft.world.ChunkRegion;
+import net.minecraft.world.chunk.AbstractChunkHolder;
+import net.minecraft.world.chunk.Chunk;
+import net.minecraft.world.chunk.ChunkGenerating;
+import net.minecraft.world.chunk.ChunkGenerationContext;
+import net.minecraft.world.chunk.ChunkGenerationStep;
+import net.minecraft.world.chunk.ProtoChunk;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import java.util.concurrent.CompletableFuture;
+
+@Mixin(ChunkGenerating.class)
+public class MixinChunkGenerating {
+
+    @ModifyReturnValue(method = "light", at = @At("RETURN"))
+    private static CompletableFuture<Chunk> applyPostprocessingAfterLighting(CompletableFuture<Chunk> original, ChunkGenerationContext context, ChunkGenerationStep step, BoundedRegionArray<AbstractChunkHolder> chunks, Chunk chunk) {
+        ServerWorld serverWorld = context.world();
+        ChunkRegion chunkRegion = new ChunkRegion(serverWorld, chunks, step, chunk);
+
+        return original.thenApply(chunk1 -> {
+            ChunkPos chunkPos = chunk1.getPos();
+
+            ShortList[] postProcessingLists = chunk1.getPostProcessingLists();
+            for (int i = 0; i < postProcessingLists.length; i++) {
+                if (postProcessingLists[i] != null) {
+                    for (ShortListIterator iterator = postProcessingLists[i].iterator(); iterator.hasNext(); ) {
+                        short short_ = iterator.nextShort();
+                        BlockPos blockPos = ProtoChunk.joinBlockPos(short_, chunk1.sectionIndexToCoord(i), chunkPos);
+                        BlockState blockState = chunk1.getBlockState(blockPos);
+
+                        if (blockState.getBlock() == Blocks.BROWN_MUSHROOM || blockState.getBlock() == Blocks.RED_MUSHROOM) {
+                            if (!blockState.canPlaceAt(chunkRegion, blockPos)) {
+                                chunkRegion.setBlockState(blockPos, Blocks.AIR.getDefaultState(), Block.NO_REDRAW | Block.FORCE_STATE);
+                            }
+                        }
+                    }
+                }
+            }
+
+            return chunk1;
+        });
+    }
+
+}

c2me-fixes-worldgen-vanilla-bugs/src/main/resources/c2me-fixes-worldgen-vanilla-bugs.mixins.json

@@ -2,8 +2,9 @@
   "parent": "c2me.mixins.json",
   "required": true,
   "package": "com.ishland.c2me.fixes.worldgen.vanilla_bugs.mixin",
-  "plugin": "com.ishland.c2me.base.common.ModuleMixinPlugin",
+  "plugin": "com.ishland.c2me.fixes.worldgen.vanilla_bugs.MixinPlugin",
   "mixins": [
-    "ensure_chunk_status_before_callback.MixinChunkHolder"
+    "ensure_chunk_status_before_callback.MixinChunkHolder",
+    "mc_276863.MixinChunkGenerating"
   ]
 }