Weight tree & cleanup

src/main/java/ru/betterend/world/generator/BiomePicker.java

@@ -8,7 +8,6 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 
 import net.minecraft.util.Identifier;
-import ru.betterend.registry.EndBiomes;
 import ru.betterend.world.biome.EndBiome;
 
 public class BiomePicker {
@@ -17,6 +16,7 @@ public class BiomePicker {
 	private float maxChanceUnmutable = 0;
 	private float maxChance = 0;
 	private int biomeCount = 0;
+	private WeighTree tree;
 	
 	public void addBiome(EndBiome biome) {
 		maxChance = biome.mutateGenChance(maxChance);
@@ -38,11 +38,7 @@ public class BiomePicker {
 	}
 	
 	public EndBiome getBiome(Random random) {
-		float chance = random.nextFloat() * maxChance;
-		for (EndBiome biome: biomes)
-			if (biome.canGenerate(chance))
-				return biome;
-		return EndBiomes.END;
+		return tree.getBiome(random.nextFloat() * maxChance);
 	}
 	
 	public List<EndBiome> getBiomes() {
@@ -52,4 +48,8 @@ public class BiomePicker {
 	public boolean containsImmutable(Identifier id) {
 		return immutableIDs.contains(id);
 	}
+	
+	public void rebuild() {
+		tree = new WeighTree(biomes);
+	}
 }

src/main/java/ru/betterend/world/generator/WeighTree.java

@@ -0,0 +1,69 @@
+package ru.betterend.world.generator;
+
+import java.util.List;
+
+import ru.betterend.world.biome.EndBiome;
+
+public class WeighTree {
+	private final Node root;
+	
+	public WeighTree(List<EndBiome> biomes) {
+		root = getNode(biomes);
+	}
+	
+	public EndBiome getBiome(float value) {
+		return root.getBiome(value);
+	}
+	
+	private Node getNode(List<EndBiome> biomes) {
+		int size = biomes.size();
+		if (size == 1) {
+			return new Leaf(biomes.get(0));
+		}
+		else if (size == 2) {
+			EndBiome first = biomes.get(0);
+			return new Branch(first.getGenChance(), new Leaf(first), new Leaf(biomes.get(1)));
+		}
+		else {
+			int index = size >> 1;
+			float separator = biomes.get(index).getGenChance();
+			Node a = getNode(biomes.subList(0, index + 1));
+			Node b = getNode(biomes.subList(index, size));
+			return new Branch(separator, a, b);
+		}
+	}
+	
+	private abstract class Node {
+		abstract EndBiome getBiome(float value);
+	}
+	
+	private class Branch extends Node {
+		final float separator;
+		final Node min;
+		final Node max;
+		
+		public Branch(float separator, Node min, Node max) {
+			this.separator = separator;
+			this.min = min;
+			this.max = max;
+		}
+
+		@Override
+		EndBiome getBiome(float value) {
+			return value < separator ? min.getBiome(value) : max.getBiome(value);
+		}
+	}
+	
+	private class Leaf extends Node {
+		final EndBiome biome;
+		
+		Leaf(EndBiome biome) {
+			this.biome = biome;
+		}
+
+		@Override
+		EndBiome getBiome(float value) {
+			return biome;
+		}
+	}
+}