Add BiomeStructure.Factory.createIndexStructure, for biome palette in…

…dices implementation

It defaults to the previous implementation

chunky/src/java/se/llbit/chunky/renderer/scene/Scene.java

@@ -966,13 +966,8 @@ public synchronized void loadChunks(TaskTracker taskTracker, World world, Collec
     Set<ChunkPosition> nonEmptyChunks = new HashSet<>();
     Set<ChunkPosition> legacyChunks = new HashSet<>();
 
-    Position2IntStructure biomePaletteIdxStructure;
+    Position2IntStructure biomePaletteIdxStructure = biomeStructureFactory.createIndexStructure();
     boolean use3dBiomes = biomeStructureFactory.is3d();
-    if (use3dBiomes) {
-      biomePaletteIdxStructure = new Position3d2IntPackedArray();
-    } else {
-      biomePaletteIdxStructure = new Position2d2IntPackedArray();
-    }
 
     final Mutable<ChunkData> chunkData1 = new Mutable<>(null); // chunk loading will switch between these two, using one asynchronously to load the data
     final Mutable<ChunkData> chunkData2 = new Mutable<>(null); // while the other is used to add to the octree

chunky/src/java/se/llbit/chunky/renderer/scene/biome/BiomeStructure.java

@@ -4,7 +4,10 @@
 import se.llbit.chunky.world.Chunk;
 import se.llbit.chunky.world.WorldTexture;
 import se.llbit.log.Log;
+import se.llbit.math.structures.Position2IntStructure;
 import se.llbit.math.structures.Position2ReferenceStructure;
+import se.llbit.math.structures.Position2d2IntPackedArray;
+import se.llbit.math.structures.Position3d2IntPackedArray;
 import se.llbit.util.annotation.NotNull;
 
 import java.io.DataInputStream;
@@ -198,6 +201,18 @@ interface Factory {
      */
     BiomeStructure create();
 
+    /**
+     * Create an empty {@link Position2IntStructure} for the biome palette indices
+     * (used only for biome blending, does not need to be saved)
+     */
+    default Position2IntStructure createIndexStructure() {
+      if(is3d()) {
+        return new Position3d2IntPackedArray();
+      } else {
+        return new Position2d2IntPackedArray();
+      }
+    }
+
     /**
      * Load a saved {@link BiomeStructure} of this implementation from a {@link DataInputStream}
      */