Implement V0 bits-per-block for Bedrock

This also improves sending empty chunks by having an empty BlockStorage array.

The empty biome data has shrunk from 32k bytes to 65.

With thanks to @dktapps.

connector/src/main/java/org/geysermc/connector/network/translators/java/level/JavaLevelChunkWithLightTranslator.java

@@ -30,6 +30,7 @@ import com.github.steveice10.mc.protocol.data.game.chunk.ChunkSection;
 import com.github.steveice10.mc.protocol.data.game.chunk.DataPalette;
 import com.github.steveice10.mc.protocol.data.game.chunk.palette.GlobalPalette;
 import com.github.steveice10.mc.protocol.data.game.chunk.palette.Palette;
+import com.github.steveice10.mc.protocol.data.game.chunk.palette.SingletonPalette;
 import com.github.steveice10.mc.protocol.data.game.level.block.BlockEntityInfo;
 import com.github.steveice10.mc.protocol.data.game.level.block.BlockEntityType;
 import com.github.steveice10.mc.protocol.packet.ingame.clientbound.level.ClientboundLevelChunkWithLightPacket;
@@ -47,6 +48,7 @@ import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.ByteBufOutputStream;
 import it.unimi.dsi.fastutil.ints.IntArrayList;
 import it.unimi.dsi.fastutil.ints.IntList;
+import it.unimi.dsi.fastutil.ints.IntLists;
 import org.geysermc.connector.network.session.GeyserSession;
 import org.geysermc.connector.network.translators.PacketTranslator;
 import org.geysermc.connector.network.translators.Translator;
@@ -59,6 +61,7 @@ import org.geysermc.connector.network.translators.world.chunk.BlockStorage;
 import org.geysermc.connector.network.translators.world.chunk.GeyserChunkSection;
 import org.geysermc.connector.network.translators.world.chunk.bitarray.BitArray;
 import org.geysermc.connector.network.translators.world.chunk.bitarray.BitArrayVersion;
+import org.geysermc.connector.network.translators.world.chunk.bitarray.SingletonBitArray;
 import org.geysermc.connector.registry.BlockRegistries;
 import org.geysermc.connector.utils.BlockEntityUtils;
 import org.geysermc.connector.utils.ChunkUtils;
@@ -145,6 +148,22 @@ public class JavaLevelChunkWithLightTranslator extends PacketTranslator<Clientbo
                     continue;
                 }
 
+                if (javaPalette instanceof SingletonPalette) {
+                    // There's only one block here. Very easy!
+                    int javaId = javaPalette.idToState(0);
+                    int bedrockId = session.getBlockMappings().getBedrockBlockId(javaId);
+                    BlockStorage blockStorage = new BlockStorage(SingletonBitArray.INSTANCE, IntLists.singleton(bedrockId));
+
+                    if (BlockRegistries.WATERLOGGED.get().contains(javaId)) {
+                        BlockStorage waterlogged = new BlockStorage(SingletonBitArray.INSTANCE, IntLists.singleton(session.getBlockMappings().getBedrockWaterId()));
+                        sections[bedrockSectionY] = new GeyserChunkSection(new BlockStorage[] {blockStorage, waterlogged});
+                    } else {
+                        sections[bedrockSectionY] = new GeyserChunkSection(new BlockStorage[] {blockStorage});
+                    }
+                    // If a chunk contains all of the same piston or flower pot then god help us
+                    continue;
+                }
+
                 IntList bedrockPalette = new IntArrayList(javaPalette.size());
                 waterloggedPaletteIds.clear();
                 pistonOrFlowerPaletteIds.clear();
@@ -270,7 +289,11 @@ public class JavaLevelChunkWithLightTranslator extends PacketTranslator<Clientbo
             int size = 0;
             for (int i = 0; i < sectionCount; i++) {
                 GeyserChunkSection section = sections[i];
-                size += (section != null ? section : session.getBlockMappings().getEmptyChunkSection()).estimateNetworkSize();
+                if (section != null) {
+                    size += section.estimateNetworkSize();
+                } else {
+                    size += SERIALIZED_CHUNK_DATA.length;
+                }
             }
             size += ChunkUtils.EMPTY_CHUNK_DATA.length; // Consists only of biome data
             size += 1; // Border blocks
@@ -281,7 +304,11 @@ public class JavaLevelChunkWithLightTranslator extends PacketTranslator<Clientbo
             byteBuf = ByteBufAllocator.DEFAULT.buffer(size);
             for (int i = 0; i < sectionCount; i++) {
                 GeyserChunkSection section = sections[i];
-                (section != null ? section : session.getBlockMappings().getEmptyChunkSection()).writeToNetwork(byteBuf);
+                if (section != null) {
+                    section.writeToNetwork(byteBuf);
+                } else {
+                    byteBuf.writeBytes(SERIALIZED_CHUNK_DATA);
+                }
             }
 
             // At this point we're dealing with Bedrock chunk sections

connector/src/main/java/org/geysermc/connector/network/translators/world/BiomeTranslator.java

@@ -29,9 +29,11 @@ import com.github.steveice10.mc.protocol.data.game.chunk.DataPalette;
 import com.github.steveice10.mc.protocol.data.game.chunk.palette.SingletonPalette;
 import com.github.steveice10.opennbt.tag.builtin.*;
 import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.IntLists;
 import org.geysermc.connector.network.session.GeyserSession;
 import org.geysermc.connector.network.translators.world.chunk.BlockStorage;
 import org.geysermc.connector.network.translators.world.chunk.GeyserChunkSection;
+import org.geysermc.connector.network.translators.world.chunk.bitarray.SingletonBitArray;
 import org.geysermc.connector.registry.Registries;
 
 import java.util.Arrays;
@@ -107,7 +109,7 @@ public class BiomeTranslator {
 
         if (biomeData.getPalette() instanceof SingletonPalette palette) {
             int biomeId = biomeTranslations.get(palette.idToState(0));
-            return new BlockStorage(biomeId);
+            return new BlockStorage(SingletonBitArray.INSTANCE, IntLists.singleton(biomeId));
         } else {
             BlockStorage storage = new BlockStorage(0);
 

connector/src/main/java/org/geysermc/connector/network/translators/world/chunk/BlockStorage.java

@@ -78,7 +78,7 @@ public class BlockStorage {
             buffer.writeIntLE(word);
         }
 
-        VarInts.writeInt(buffer, palette.size());
+        bitArray.writeSizeToNetwork(buffer, palette.size());
         palette.forEach((IntConsumer) id -> VarInts.writeInt(buffer, id));
     }
 

connector/src/main/java/org/geysermc/connector/network/translators/world/chunk/bitarray/BitArray.java

@@ -25,6 +25,9 @@
 
 package org.geysermc.connector.network.translators.world.chunk.bitarray;
 
+import com.nukkitx.network.VarInts;
+import io.netty.buffer.ByteBuf;
+
 public interface BitArray {
 
     void set(int index, int value);
@@ -33,6 +36,13 @@ public interface BitArray {
 
     int size();
 
+    /**
+     * Overridden if the bit array implementation does not require size.
+     */
+    default void writeSizeToNetwork(ByteBuf buffer, int size) {
+        VarInts.writeInt(buffer, size);
+    }
+
     int[] getWords();
 
     BitArrayVersion getVersion();

connector/src/main/java/org/geysermc/connector/network/translators/world/chunk/bitarray/BitArrayVersion.java

@@ -35,7 +35,8 @@ public enum BitArrayVersion {
     V4(4, 8, V5),
     V3(3, 10, V4), // 2 bit padding
     V2(2, 16, V3),
-    V1(1, 32, V2);
+    V1(1, 32, V2),
+    V0(0, 0, V1);
 
     private static final BitArrayVersion[] VALUES = values();
 
@@ -94,6 +95,8 @@ public enum BitArrayVersion {
         if (this == V3 || this == V5 || this == V6) {
             // Padded palettes aren't able to use bitwise operations due to their padding.
             return new PaddedBitArray(this, size, words);
+        } else if (this == V0) {
+            return new SingletonBitArray();
         } else {
             return new Pow2BitArray(this, size, words);
         }

connector/src/main/java/org/geysermc/connector/network/translators/world/chunk/bitarray/SingletonBitArray.java

@@ -23,36 +23,49 @@
  * @link https://github.com/GeyserMC/Geyser
  */
 
-package org.geysermc.connector.network.translators.world.chunk;
+package org.geysermc.connector.network.translators.world.chunk.bitarray;
 
-import com.nukkitx.nbt.NBTOutputStream;
+import io.netty.buffer.ByteBuf;
-import com.nukkitx.nbt.NbtMap;
-import com.nukkitx.nbt.NbtUtils;
-import lombok.Getter;
 
-import java.io.ByteArrayOutputStream;
+public class SingletonBitArray implements BitArray {
-import java.io.IOException;
+    public static final SingletonBitArray INSTANCE = new SingletonBitArray();
 
-public class EmptyChunkProvider {
+    private static final int[] EMPTY_ARRAY = new int[0];
-    @Getter
-    private final byte[] emptyLevelChunkData;
-    @Getter
-    private final GeyserChunkSection emptySection;
 
-    public EmptyChunkProvider(int airId) {
+    public SingletonBitArray() {
-        BlockStorage emptyStorage = new BlockStorage(airId);
+    }
-        emptySection = new GeyserChunkSection(new BlockStorage[]{emptyStorage});
 
-        try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
+    @Override
-            outputStream.write(new byte[258]); // Biomes + Border Size + Extra Data Size
+    public void set(int index, int value) {
+    }
 
-            try (NBTOutputStream stream = NbtUtils.createNetworkWriter(outputStream)) {
+    @Override
-                stream.writeTag(NbtMap.EMPTY);
+    public int get(int index) {
-            }
+        return 0;
+    }
 
-            emptyLevelChunkData = outputStream.toByteArray();
+    @Override
-        } catch (IOException e) {
+    public int size() {
-            throw new AssertionError("Unable to generate empty level chunk data");
+        return 1;
-        }
+    }
+
+    @Override
+    public void writeSizeToNetwork(ByteBuf buffer, int size) {
+        // no-op - size is fixed
+    }
+
+    @Override
+    public int[] getWords() {
+        return EMPTY_ARRAY;
+    }
+
+    @Override
+    public BitArrayVersion getVersion() {
+        return BitArrayVersion.V0;
+    }
+
+    @Override
+    public SingletonBitArray copy() {
+        return new SingletonBitArray();
     }
 }

connector/src/main/java/org/geysermc/connector/registry/populator/BlockRegistryPopulator.java

@@ -38,8 +38,6 @@ import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.objects.ObjectIntPair;
 import org.geysermc.connector.GeyserConnector;
 import org.geysermc.connector.network.translators.world.block.BlockStateValues;
-import org.geysermc.connector.network.translators.world.chunk.BlockStorage;
-import org.geysermc.connector.network.translators.world.chunk.GeyserChunkSection;
 import org.geysermc.connector.registry.BlockRegistries;
 import org.geysermc.connector.registry.type.BlockMapping;
 import org.geysermc.connector.registry.type.BlockMappings;
@@ -200,7 +198,6 @@ public class BlockRegistryPopulator {
             builder.bedrockBlockStates(blocksTag);
 
             BlockRegistries.BLOCKS.register(palette.getKey().valueInt(), builder.blockStateVersion(stateVersion)
-                    .emptyChunkSection(new GeyserChunkSection(new BlockStorage[]{new BlockStorage(airRuntimeId)}))
                     .javaToBedrockBlocks(javaToBedrockBlocks)
                     .javaIdentifierToBedrockTag(javaIdentifierToBedrockTag)
                     .itemFrames(itemFrames)

connector/src/main/java/org/geysermc/connector/registry/type/BlockMappings.java

@@ -31,7 +31,6 @@ import it.unimi.dsi.fastutil.ints.IntSet;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import lombok.Builder;
 import lombok.Value;
-import org.geysermc.connector.network.translators.world.chunk.GeyserChunkSection;
 
 import java.util.Map;
 
@@ -44,8 +43,6 @@ public class BlockMappings {
 
     int blockStateVersion;
 
-    GeyserChunkSection emptyChunkSection;
-
     int[] javaToBedrockBlocks;
 
     NbtList<NbtMap> bedrockBlockStates;

connector/src/main/java/org/geysermc/connector/utils/ChunkUtils.java

@@ -36,6 +36,7 @@ import com.nukkitx.protocol.bedrock.packet.NetworkChunkPublisherUpdatePacket;
 import com.nukkitx.protocol.bedrock.packet.UpdateBlockPacket;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import it.unimi.dsi.fastutil.ints.IntLists;
 import lombok.experimental.UtilityClass;
 import org.geysermc.connector.entity.ItemFrameEntity;
 import org.geysermc.connector.entity.player.SkullPlayerEntity;
@@ -43,6 +44,8 @@ import org.geysermc.connector.network.session.GeyserSession;
 import org.geysermc.connector.network.translators.world.block.BlockStateValues;
 import org.geysermc.connector.network.translators.world.block.entity.BedrockOnlyBlockEntity;
 import org.geysermc.connector.network.translators.world.chunk.BlockStorage;
+import org.geysermc.connector.network.translators.world.chunk.GeyserChunkSection;
+import org.geysermc.connector.network.translators.world.chunk.bitarray.SingletonBitArray;
 import org.geysermc.connector.registry.BlockRegistries;
 
 import static org.geysermc.connector.network.translators.world.block.BlockStateValues.JAVA_AIR_ID;
@@ -60,13 +63,30 @@ public class ChunkUtils {
     public static final int MAXIMUM_ACCEPTED_HEIGHT = 256;
     public static final int MAXIMUM_ACCEPTED_HEIGHT_OVERWORLD = 384;
 
+    /**
+     * An empty subchunk.
+     */
+    public static final byte[] SERIALIZED_CHUNK_DATA;
+    /**
+     * An empty chunk that can be safely passed on to a LevelChunkPacket with subcounts set to 0.
+     */
     public static final byte[] EMPTY_CHUNK_DATA;
     public static final byte[] EMPTY_BIOME_DATA;
 
     static {
         ByteBuf byteBuf = Unpooled.buffer();
         try {
-            BlockStorage blockStorage = new BlockStorage(0);
+            new GeyserChunkSection(new BlockStorage[0])
+                    .writeToNetwork(byteBuf);
+            SERIALIZED_CHUNK_DATA = new byte[byteBuf.readableBytes()];
+            byteBuf.readBytes(SERIALIZED_CHUNK_DATA);
+        } finally {
+            byteBuf.release();
+        }
+
+        byteBuf = Unpooled.buffer();
+        try {
+            BlockStorage blockStorage = new BlockStorage(SingletonBitArray.INSTANCE, IntLists.singleton(0));
             blockStorage.writeToNetwork(byteBuf);
 
             EMPTY_BIOME_DATA = new byte[byteBuf.readableBytes()];