Save palette along with the chunk (fixes #62)

src/main/java/org/dimdev/vanillafix/VanillaFix.java

@@ -90,7 +90,7 @@ public void onPreInit(FMLPreInitializationEvent event) {
         }
 
         if (DEBUG_ITEM_IDS) {
-            for (int i = 0; i < 5000; i++) {
+            for (int i = 0; i < 40000; i++) {
                 Item item = new Item()
                         .setCreativeTab(CreativeTabs.FOOD)
                         .setUnlocalizedName("item_" + i)

src/main/java/org/dimdev/vanillafix/idlimit/IPatchedBlockStateContainer.java

@@ -0,0 +1,6 @@
+package org.dimdev.vanillafix.idlimit;
+
+public interface IPatchedBlockStateContainer {
+    void setTemporaryPalette(int[] temporaryPalette);
+    int[] getTemporaryPalette();
+}

src/main/java/org/dimdev/vanillafix/idlimit/mixins/MixinAnvilChunkLoader.java

@@ -0,0 +1,35 @@
+package org.dimdev.vanillafix.idlimit.mixins;
+
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.nbt.NBTTagList;
+import net.minecraft.world.World;
+import net.minecraft.world.chunk.Chunk;
+import net.minecraft.world.chunk.NibbleArray;
+import net.minecraft.world.chunk.storage.AnvilChunkLoader;
+import net.minecraft.world.chunk.storage.ExtendedBlockStorage;
+import org.dimdev.vanillafix.idlimit.IPatchedBlockStateContainer;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+import org.spongepowered.asm.mixin.injection.callback.LocalCapture;
+
+@Mixin(AnvilChunkLoader.class)
+public class MixinAnvilChunkLoader {
+    @Inject(method = "readChunkFromNBT", at = @At(value = "INVOKE", target = "Lnet/minecraft/world/chunk/storage/ExtendedBlockStorage;<init>(IZ)V", shift = At.Shift.BY, by = 2), locals = LocalCapture.CAPTURE_FAILHARD)
+    private void readPaletteNBT(World world, NBTTagCompound nbt, CallbackInfoReturnable<Chunk> cir,
+            int ignored0, int ignored1, Chunk ignored2, NBTTagList ignored3, int ingnored4, ExtendedBlockStorage[] ignored5, boolean ignored6, int ignored7,
+            NBTTagCompound storageNBT, int y, ExtendedBlockStorage extendedBlockStorage) {
+        int[] palette = storageNBT.hasKey("Palette", 11) ? storageNBT.getIntArray("Palette") : null;
+        ((IPatchedBlockStateContainer) extendedBlockStorage.getData()).setTemporaryPalette(palette);
+    }
+
+    @Inject(method = "writeChunkToNBT", at = @At(value = "INVOKE_ASSIGN", target = "Lnet/minecraft/world/chunk/BlockStateContainer;getDataForNBT([BLnet/minecraft/world/chunk/NibbleArray;)Lnet/minecraft/world/chunk/NibbleArray;", ordinal = 0), locals = LocalCapture.CAPTURE_FAILHARD)
+    private void writePaletteNBT(Chunk chunk, World worldIn, NBTTagCompound nbt, CallbackInfo ci,
+            ExtendedBlockStorage[] ignored0, NBTTagList ignored1, boolean ignored2, ExtendedBlockStorage[] ignored3, int ignored4, int ignored5,
+            ExtendedBlockStorage extendedBlockStorage, NBTTagCompound storageNBT, byte[] blocks, NibbleArray data, NibbleArray add) {
+        int[] palette = ((IPatchedBlockStateContainer) extendedBlockStorage.getData()).getTemporaryPalette();
+        storageNBT.setIntArray("Palette", palette);
+    }
+}

src/main/java/org/dimdev/vanillafix/idlimit/mixins/MixinBlockStateContainer.java

@@ -0,0 +1,113 @@
+package org.dimdev.vanillafix.idlimit.mixins;
+
+import net.minecraft.block.Block;
+import net.minecraft.block.state.IBlockState;
+import net.minecraft.util.BitArray;
+import net.minecraft.world.chunk.BlockStateContainer;
+import net.minecraft.world.chunk.IBlockStatePalette;
+import net.minecraft.world.chunk.NibbleArray;
+import org.dimdev.vanillafix.idlimit.IPatchedBlockStateContainer;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+import java.util.*;
+
+@Mixin(BlockStateContainer.class)
+public abstract class MixinBlockStateContainer implements IPatchedBlockStateContainer {
+    @Shadow protected abstract IBlockState get(int index);
+    @Shadow protected BitArray storage;
+    @Shadow protected IBlockStatePalette palette;
+    @Shadow protected abstract void set(int index, IBlockState state);
+    @Shadow protected abstract void setBits(int bitsIn);
+
+    private static boolean shouldUseVFFormat;
+    private static boolean shouldUseVFFormatDetermined;
+    private int[] temporaryPalette; // index -> state id
+
+    private boolean shouldUseVFFormat() {
+        if (!shouldUseVFFormatDetermined) {
+            for (Block block : Block.REGISTRY) {
+                int id = Block.REGISTRY.getIDForObject(block);
+                if (id > 4096) {
+                    shouldUseVFFormat = true;
+                    break;
+                }
+            }
+            shouldUseVFFormatDetermined = true;
+        }
+        return shouldUseVFFormat;
+    }
+
+    @Override
+    public int[] getTemporaryPalette() {
+        return temporaryPalette;
+    }
+
+    @Override
+    public void setTemporaryPalette(int[] temporaryPalette) {
+        this.temporaryPalette = temporaryPalette;
+    }
+
+    /**
+     * @reason If this BlockStateContainer should be saved in VanillaFix format,
+     * store palette IDs rather than block IDs in the container's "Blocks" and
+     * "Data" arrays.
+     */
+    @SuppressWarnings("deprecation")
+    @Inject(method = "getDataForNBT", at = @At("HEAD"), cancellable = true)
+    private void getDataForNBTVF(byte[] blockIds, NibbleArray data, CallbackInfoReturnable<NibbleArray> cir) {
+        if (!shouldUseVFFormat()) return; // Save containters in VF format only if 4096 IDs are being used TODO: only if this containter contains IDs >4096?
+
+        HashMap<IBlockState, Integer> stateIDMap = new HashMap<>();
+        int nextID = 0;
+        for (int index = 0; index < 4096; ++index) {
+            IBlockState state = get(index);
+            Integer paletteID = stateIDMap.get(state);
+            if (paletteID == null) {
+                paletteID = nextID++;
+                stateIDMap.put(state, paletteID);
+            }
+
+            int x = index & 15;
+            int y = index >> 8 & 15;
+            int z = index >> 4 & 15;
+
+            blockIds[index] = (byte) (paletteID >> 4 & 255);
+            data.set(x, y, z, paletteID & 15);
+        }
+
+        temporaryPalette = new int[nextID];
+        for (Map.Entry<IBlockState, Integer> entry : stateIDMap.entrySet()) {
+            temporaryPalette[entry.getValue()] = Block.BLOCK_STATE_IDS.get(entry.getKey());
+        }
+
+        cir.setReturnValue(null);
+        cir.cancel();
+    }
+
+    /**
+     * @reason If this BlockStateContainer is saved in VanillaFix format, treat
+     * the "Blocks" and "Data" arrays as palette IDs.
+     */
+    @SuppressWarnings("deprecation")
+    @Inject(method = "setDataFromNBT", at = @At("HEAD"), cancellable = true)
+    private void setDataFromNBTVF(byte[] blockIds, NibbleArray data, NibbleArray blockIdExtension, CallbackInfo ci) {
+        if (temporaryPalette == null) return; // Read containers in VF format only if container was saved in VF format (has a palette)
+
+        for (int index = 0; index < 4096; ++index) {
+            int x = index & 15;
+            int y = index >> 8 & 15;
+            int z = index >> 4 & 15;
+            int paletteID = (blockIds[index] & 255) << 4 | data.get(x, y, z);
+
+            set(index, Block.BLOCK_STATE_IDS.getByValue(temporaryPalette[paletteID]));
+        }
+
+        temporaryPalette = null;
+        ci.cancel();
+    }
+}

src/main/resources/mixins.vanillafix.idlimit.json

@@ -8,7 +8,9 @@
   "compatibilityLevel": "JAVA_8",
   "mixins": [
     "MixinGameData",
-    "MixinStatList"
+    "MixinStatList",
+    "MixinBlockStateContainer",
+    "MixinAnvilChunkLoader"
   ],
   "client": [],
   "injectors": {