Add custom world identifiers

api/src/main/java/net/elytrium/limboapi/api/LimboFactory.java

@@ -118,6 +118,24 @@ public interface LimboFactory {
    */
   VirtualWorld createVirtualWorld(Dimension dimension, double posX, double posY, double posZ, float yaw, float pitch);
 
+  /**
+   * Creates a new virtual world with a custom identifier.
+   *
+   * @param dimension World dimension type.
+   * @param worldName Namespaced identifier used to distinguish the world on modern clients.
+   * @param posX      Spawn location. (X)
+   * @param posY      Spawn location. (Y)
+   * @param posZ      Spawn location. (Z)
+   * @param yaw       Spawn rotation. (Yaw)
+   * @param pitch     Spawn rotation. (Pitch)
+   *
+   * @return new virtual world.
+   */
+  default VirtualWorld createVirtualWorld(Dimension dimension, String worldName,
+      double posX, double posY, double posZ, float yaw, float pitch) {
+    throw new UnsupportedOperationException("Custom world names are not supported by this LimboFactory");
+  }
+
   /**
    * Creates new virtual chunk with plain biomes set as default.
    * You need to provide the chunk location, you can get it using {@code blockCoordinate >> 4}.

api/src/main/java/net/elytrium/limboapi/api/chunk/VirtualWorld.java

@@ -46,6 +46,16 @@ public interface VirtualWorld {
   @NonNull
   Dimension getDimension();
 
+  /**
+   * Returns the identifier used to distinguish this world from other worlds on modern clients.
+   *
+   * @return the namespaced world identifier.
+   */
+  @NonNull
+  default String getWorldName() {
+    return this.getDimension().getKey();
+  }
+
   double getSpawnX();
 
   double getSpawnY();

plugin/src/main/java/net/elytrium/limboapi/LimboAPI.java

@@ -380,6 +380,12 @@ public VirtualWorld createVirtualWorld(Dimension dimension, double posX, double
     return new SimpleWorld(dimension, posX, posY, posZ, yaw, pitch);
   }
 
+  @Override
+  public VirtualWorld createVirtualWorld(Dimension dimension, String worldName,
+      double posX, double posY, double posZ, float yaw, float pitch) {
+    return new SimpleWorld(dimension, worldName, posX, posY, posZ, yaw, pitch);
+  }
+
   @Override
   public VirtualChunk createVirtualChunk(int posX, int posZ) {
     return new SimpleChunk(posX, posZ);

plugin/src/main/java/net/elytrium/limboapi/server/LimboImpl.java

@@ -112,6 +112,7 @@
 import net.elytrium.limboapi.protocol.packets.s2c.TimeUpdatePacket;
 import net.elytrium.limboapi.protocol.packets.s2c.UpdateViewPositionPacket;
 import net.elytrium.limboapi.server.world.SimpleTagManager;
+import net.kyori.adventure.key.Key;
 import net.kyori.adventure.nbt.BinaryTag;
 import net.kyori.adventure.nbt.BinaryTagIO;
 import net.kyori.adventure.nbt.BinaryTagTypes;
@@ -148,6 +149,8 @@ public class LimboImpl implements Limbo {
   private final RootCommandNode<CommandSource> commandNode = new RootCommandNode<>();
   private final ReadWriteLock lock = new ReentrantReadWriteLock();
   private final List<PreparedPacket> queuedToRelease = new ArrayList<>();
+  private final String worldName;
+  private final ImmutableSet<String> levelNames;
   private final List<CommandRegistrar<?>> registrars = ImmutableList.of(
       new BrigadierCommandRegistrar(this.commandNode, this.lock.writeLock()),
       new SimpleCommandRegistrar(this.commandNode, this.lock.writeLock()),
@@ -182,6 +185,11 @@ public class LimboImpl implements Limbo {
   public LimboImpl(LimboAPI plugin, VirtualWorld world) {
     this.plugin = plugin;
     this.world = world;
+    this.worldName = Key.key(world.getWorldName()).asString();
+    this.levelNames = ImmutableSet.<String>builder()
+        .addAll(LEVELS)
+        .add(this.worldName)
+        .build();
     this.localStateRegistry = LimboProtocol.getLimboStateRegistry();
 
     this.refresh();
@@ -987,7 +995,9 @@ private JoinGamePacket createJoinGamePacket(ProtocolVersion version) {
     joinGame.setReducedDebugInfo(this.reducedDebugInfo);
 
     String key = dimension.getKey();
-    joinGame.setDimensionInfo(new DimensionInfo(key, key, false, false, version));
+    String registryIdentifier = version.noLessThan(ProtocolVersion.MINECRAFT_1_16_2)
+        && version.lessThan(ProtocolVersion.MINECRAFT_1_19) ? this.worldName : key;
+    joinGame.setDimensionInfo(new DimensionInfo(registryIdentifier, this.worldName, false, false, version));
     joinGame.setEnforcesSecureChat(Settings.IMP.MAIN.SEND_ENFORCE_SECURE_CHAT);
 
     CompoundBinaryTag.Builder registryContainer = CompoundBinaryTag.builder();
@@ -1323,7 +1333,7 @@ private JoinGamePacket createJoinGamePacket(ProtocolVersion version) {
       }
 
       CURRENT_DIMENSION_DATA_FIELD.invokeExact(joinGame, currentDimensionData);
-      LEVEL_NAMES_FIELDS.invokeExact(joinGame, LEVELS);
+      LEVEL_NAMES_FIELDS.invokeExact(joinGame, this.levelNames);
       REGISTRY_FIELD.invokeExact(joinGame, registryContainer.build());
     } catch (Throwable e) {
       throw new ReflectionException(e);
@@ -1346,7 +1356,7 @@ private JoinGamePacket createLegacyJoinGamePacket() {
   }
 
   private DefaultSpawnPositionPacket createDefaultSpawnPositionPacket() {
-    return new DefaultSpawnPositionPacket(this.world.getDimension().getKey(),
+    return new DefaultSpawnPositionPacket(this.worldName,
         (int) this.world.getSpawnX(), (int) this.world.getSpawnY(), (int) this.world.getSpawnZ(), 0.0F, 0.0f);
   }
 

plugin/src/main/java/net/elytrium/limboapi/server/world/SimpleWorld.java

@@ -34,6 +34,7 @@
 import net.elytrium.limboapi.api.chunk.VirtualWorld;
 import net.elytrium.limboapi.material.Biome;
 import net.elytrium.limboapi.server.world.chunk.SimpleChunk;
+import net.kyori.adventure.key.Key;
 import net.kyori.adventure.nbt.CompoundBinaryTag;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -44,6 +45,8 @@ public class SimpleWorld implements VirtualWorld {
   private final List<List<VirtualChunk>> distanceChunkMap = new ArrayList<>();
   @NonNull
   private final Dimension dimension;
+  @NonNull
+  private final String worldName;
   private final VirtualBiome defaultBiome;
 
   private final double spawnX;
@@ -53,7 +56,13 @@ public class SimpleWorld implements VirtualWorld {
   private final float pitch;
 
   public SimpleWorld(@NonNull Dimension dimension, double posX, double posY, double posZ, float yaw, float pitch) {
+    this(dimension, dimension.getKey(), posX, posY, posZ, yaw, pitch);
+  }
+
+  public SimpleWorld(@NonNull Dimension dimension, @NonNull String worldName,
+      double posX, double posY, double posZ, float yaw, float pitch) {
     this.dimension = dimension;
+    this.worldName = Key.key(worldName).asString();
     this.defaultBiome = Biome.of(dimension.getDefaultBiome());
 
     this.spawnX = posX;
@@ -183,6 +192,12 @@ public Dimension getDimension() {
     return this.dimension;
   }
 
+  @NonNull
+  @Override
+  public String getWorldName() {
+    return this.worldName;
+  }
+
   @Override
   public double getSpawnX() {
     return this.spawnX;