From d58eb699f1fb96867f14cf8454c535cde633b0fd Mon Sep 17 00:00:00 2001
From: dfsek <dfsek@protonmail.com>
Date: Sat, 11 Jun 2022 21:39:15 -0700
Subject: [PATCH] create ChunkLocalCachingBiomeProvider

---
 .../world/biome/generation/BiomeProvider.java |  4 +-
 .../generation/CachingBiomeProvider.java      |  6 +-
 .../ChunkLocalCachingBiomeProvider.java       | 75 +++++++++++++++++++
 3 files changed, 80 insertions(+), 5 deletions(-)
 create mode 100644 common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/ChunkLocalCachingBiomeProvider.java

diff --git a/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/BiomeProvider.java b/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/BiomeProvider.java
index 37483b564..49726c835 100644
--- a/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/BiomeProvider.java
+++ b/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/BiomeProvider.java
@@ -92,11 +92,11 @@ public interface BiomeProvider {
         return StreamSupport.stream(getBiomes().spliterator(), false);
     }
     
-    default BiomeProvider caching(int minY, int maxY) {
+    default CachingBiomeProvider caching(int minY, int maxY) {
         return new CachingBiomeProvider(this, minY, maxY);
     }
     
-    default BiomeProvider caching(WorldProperties worldProperties) {
+    default CachingBiomeProvider caching(WorldProperties worldProperties) {
         return caching(worldProperties.getMinHeight(), worldProperties.getMaxHeight());
     }
 }
diff --git a/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/CachingBiomeProvider.java b/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/CachingBiomeProvider.java
index 08877f968..bf954f2cd 100644
--- a/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/CachingBiomeProvider.java
+++ b/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/CachingBiomeProvider.java
@@ -18,9 +18,9 @@ import java.util.Optional;
  * This is for use in chunk generators, it makes the assumption that <b>the seed remains the same for the duration of its use!</b>
  */
 public class CachingBiomeProvider implements BiomeProvider, Handle {
-    private final BiomeProvider delegate;
-    private final int minY;
-    private final int maxY;
+    protected final BiomeProvider delegate;
+    protected final int minY;
+    protected final int maxY;
     private final Map<Long, Biome[]> cache = new HashMap<>();
     private final Map<Long, Column<Biome>> columnCache = new HashMap<>();
     
diff --git a/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/ChunkLocalCachingBiomeProvider.java b/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/ChunkLocalCachingBiomeProvider.java
new file mode 100644
index 000000000..deb74d97b
--- /dev/null
+++ b/common/api/src/main/java/com/dfsek/terra/api/world/biome/generation/ChunkLocalCachingBiomeProvider.java
@@ -0,0 +1,75 @@
+package com.dfsek.terra.api.world.biome.generation;
+
+import com.dfsek.terra.api.util.Column;
+import com.dfsek.terra.api.world.biome.Biome;
+import com.dfsek.terra.api.world.info.WorldProperties;
+
+import net.jafama.FastMath;
+
+import java.util.Optional;
+
+
+/**
+ * A biome provider implementation that lazily evaluates biomes, and caches them.
+ * <p>
+ * This is for use in chunk generators, it makes the assumption that <b>the seed remains the same for the duration of its use!</b>
+ * <p>
+ * The cache works the best when all biomes are within one chunk! This is because internally, there are two caches, one constant-size one
+ * for the chunk, and a slower dynamically-sized cache for out-of-chunk biomes.
+ */
+public class ChunkLocalCachingBiomeProvider extends CachingBiomeProvider {
+    private final Biome[][][] cache;
+    private final Column<Biome>[][] columnCache = new Column<>[16][16];
+    
+    private final int chunkX;
+    private final int chunkZ;
+    
+    protected ChunkLocalCachingBiomeProvider(BiomeProvider delegate, WorldProperties worldProperties, int chunkX, int chunkZ) {
+        super(delegate, worldProperties.getMinHeight(), worldProperties.getMaxHeight());
+        this.cache = new Biome[16][maxY - minY][16];
+        this.chunkX = chunkX;
+        this.chunkZ = chunkZ;
+    }
+    
+    @Override
+    public BiomeProvider getHandle() {
+        return delegate;
+    }
+    
+    @Override
+    public Biome getBiome(int x, int y, int z, long seed) {
+        if(FastMath.floorDiv(x, 16) == chunkX && FastMath.floorDiv(z, 16) == chunkZ) {
+            Biome biome = cache[x & 15][y - minY][z & 15];
+            if(biome == null) {
+                biome = delegate.getBiome(x, y, z, seed);
+                cache[x & 15][y - minY][z & 15] = biome;
+            }
+            return biome;
+        }
+        
+        return super.getBiome(x, y, z, seed);
+    }
+    
+    @Override
+    public Optional<Biome> getBaseBiome(int x, int z, long seed) {
+        return delegate.getBaseBiome(x, z, seed);
+    }
+    
+    @Override
+    public Column<Biome> getColumn(int x, int z, long seed, int min, int max) {
+        if(FastMath.floorDiv(x, 16) == chunkX && FastMath.floorDiv(z, 16) == chunkZ) {
+            Column<Biome> column = columnCache[x & 15][z & 15];
+            if(column == null) {
+                column = delegate.getColumn(x, z, seed, min, max);
+                columnCache[x & 15][z & 15] = column;
+            }
+            return column;
+        }
+        return super.getColumn(x, z, seed, min, max);
+    }
+    
+    @Override
+    public Iterable<Biome> getBiomes() {
+        return delegate.getBiomes();
+    }
+}