Added ChunkSnapShot improvements. Thanks mikeprimm!

Added support for biome data to chunk snapshot
Added method for returning empty chunk snapshot (for ungenerated chunks)

src/main/java/org/bukkit/craftbukkit/CraftChunk.java

@@ -13,6 +13,8 @@ import org.bukkit.craftbukkit.block.CraftBlock;
 import org.bukkit.entity.Entity;
 import org.bukkit.craftbukkit.util.ConcurrentSoftMap;
 import org.bukkit.ChunkSnapshot;
+import net.minecraft.server.BiomeBase;
+import net.minecraft.server.WorldChunkManager;
 
 public class CraftChunk implements Chunk {
     private WeakReference<net.minecraft.server.Chunk> weakChunk;
@@ -111,13 +113,100 @@ public class CraftChunk implements Chunk {
      * @return ChunkSnapshot
      */
     public ChunkSnapshot getChunkSnapshot() {
+        return getChunkSnapshot(true, false, false);
+    }
+
+    /**
+     * Capture thread-safe read-only snapshot of chunk data
+     * @param includeMaxblocky - if true, snapshot includes per-coordinate maximum Y values
+     * @param includeBiome - if true, snapshot includes per-coordinate biome type
+     * @param includeBiomeTempRain - if true, snapshot includes per-coordinate raw biome temperature and rainfall
+     * @return ChunkSnapshot
+     */
+    public ChunkSnapshot getChunkSnapshot(boolean includeMaxblocky, boolean includeBiome, boolean includeBiomeTempRain) {
         net.minecraft.server.Chunk chunk = getHandle();
         byte[] buf = new byte[32768 + 16384 + 16384 + 16384]; // Get big enough buffer for whole chunk
         chunk.a(buf, 0, 0, 0, 16, 128, 16, 0); // Get whole chunk
-        byte[] hmap = new byte[256]; // Get copy of height map
-        System.arraycopy(chunk.h, 0, hmap, 0, 256);
+        byte[] hmap = null;
+
+        if (includeMaxblocky) {
+            hmap = new byte[256]; // Get copy of height map
+            System.arraycopy(chunk.h, 0, hmap, 0, 256);
+        }
+
+        BiomeBase[] biome = null;
+        double[] biomeTemp = null;
+        double[] biomeRain = null;
+
+        if (includeBiome || includeBiomeTempRain) {
+            WorldChunkManager wcm = chunk.world.getWorldChunkManager();
+            BiomeBase[] bb = wcm.a(getX()<<4, getZ()<<4, 16, 16);
+
+            if (includeBiome) {
+                biome = new BiomeBase[256];
+                System.arraycopy(bb, 0, biome, 0, biome.length);
+            }
+
+            if (includeBiomeTempRain) {
+                biomeTemp = new double[256];
+                biomeRain = new double[256];
+                System.arraycopy(wcm.a, 0, biomeTemp, 0, biomeTemp.length);
+                System.arraycopy(wcm.b, 0, biomeRain, 0, biomeRain.length);
+            }
+        }
         World w = getWorld();
-        return new CraftChunkSnapshot(getX(), getZ(), w.getName(), w.getFullTime(), buf, hmap);
+        return new CraftChunkSnapshot(getX(), getZ(), w.getName(), w.getFullTime(), buf, hmap, biome, biomeTemp, biomeRain);
+    }
+    /**
+     * Empty chunk snapshot - nothing but air blocks, but can include valid biome data
+     */
+    private static class EmptyChunkSnapshot extends CraftChunkSnapshot {
+        EmptyChunkSnapshot(int x, int z, String w, long wtime, BiomeBase[] biome, double[] biomeTemp, double[] biomeRain) {
+            super(x, z, w, wtime, null, null, biome, biomeTemp, biomeRain);
+        }
+
+        public final int getBlockTypeId(int x, int y, int z) {
+            return 0;
+        }
+
+        public final int getBlockData(int x, int y, int z) {
+            return 0;
+        }
+
+        public final int getBlockSkyLight(int x, int y, int z) {
+            return 15;
+        }
+
+        public final int getBlockEmittedLight(int x, int y, int z) {
+            return 0;
+        }
+
+        public final int getHighestBlockYAt(int x, int z) {
+            return 0;
+        }
     }
 
+    public static ChunkSnapshot getEmptyChunkSnapshot(int x, int z, CraftWorld w, boolean includeBiome, boolean includeBiomeTempRain) {
+        BiomeBase[] biome = null;
+        double[] biomeTemp = null;
+        double[] biomeRain = null;
+
+        if (includeBiome || includeBiomeTempRain) {
+            WorldChunkManager wcm = w.getHandle().getWorldChunkManager();
+            BiomeBase[] bb = wcm.a(x<<4, z<<4, 16, 16);
+
+            if (includeBiome) {
+                biome = new BiomeBase[256];
+                System.arraycopy(bb, 0, biome, 0, biome.length);
+            }
+
+            if (includeBiomeTempRain) {
+                biomeTemp = new double[256];
+                biomeRain = new double[256];
+                System.arraycopy(wcm.a, 0, biomeTemp, 0, biomeTemp.length);
+                System.arraycopy(wcm.b, 0, biomeRain, 0, biomeRain.length);
+            }
+        }
+        return new EmptyChunkSnapshot(x, z, w.getName(), w.getFullTime(), biome, biomeTemp, biomeRain);
+    }
 }

src/main/java/org/bukkit/craftbukkit/CraftChunkSnapshot.java

@@ -1,6 +1,9 @@
 package org.bukkit.craftbukkit;
 
 import org.bukkit.ChunkSnapshot;
+import org.bukkit.block.Biome;
+
+import net.minecraft.server.BiomeBase;
 /**
  * Represents a static, thread-safe snapshot of chunk of blocks
  * Purpose is to allow clean, efficient copy of a chunk data to be made, and then handed off for processing in another thread (e.g. map rendering)
@@ -10,7 +13,10 @@ public class CraftChunkSnapshot implements ChunkSnapshot {
     private final String worldname;
     private final byte[] buf; // Flat buffer in uncompressed chunk file format
     private final byte[] hmap; // Height map
-    private final long capture_fulltime;
+    private final long captureFulltime;
+    private final BiomeBase[] biome;
+    private final double[] biomeTemp;
+    private final double[] biomeRain;
 
     private static final int BLOCKDATA_OFF = 32768;
     private static final int BLOCKLIGHT_OFF = BLOCKDATA_OFF + 16384;
@@ -19,13 +25,16 @@ public class CraftChunkSnapshot implements ChunkSnapshot {
     /**
      * Constructor
      */
-    CraftChunkSnapshot(int x, int z, String wname, long wtime, byte[] buf, byte[] hmap) {
+    CraftChunkSnapshot(int x, int z, String wname, long wtime, byte[] buf, byte[] hmap, BiomeBase[] biome, double[] biomeTemp, double[] biomeRain) {
         this.x = x;
         this.z = z;
         this.worldname = wname;
-        this.capture_fulltime = wtime;
+        this.captureFulltime = wtime;
         this.buf = buf;
         this.hmap = hmap;
+        this.biome = biome;
+        this.biomeTemp = biomeTemp;
+        this.biomeRain = biomeRain;
     }
 
     /**
@@ -120,11 +129,71 @@ public class CraftChunkSnapshot implements ChunkSnapshot {
         return hmap[z << 4 | x] & 255;
     }
 
+    /**
+     * Get biome at given coordinates
+     *
+     * @param x X-coordinate
+     * @param z Z-coordinate
+     * @return Biome at given coordinate
+     */
+    public Biome getBiome(int x, int z) {
+        BiomeBase base = biome[x << 4 | z];
+
+        if (base == BiomeBase.RAINFOREST) {
+            return Biome.RAINFOREST;
+        } else if (base == BiomeBase.SWAMPLAND) {
+            return Biome.SWAMPLAND;
+        } else if (base == BiomeBase.SEASONAL_FOREST) {
+            return Biome.SEASONAL_FOREST;
+        } else if (base == BiomeBase.FOREST) {
+            return Biome.FOREST;
+        } else if (base == BiomeBase.SAVANNA) {
+            return Biome.SAVANNA;
+        } else if (base == BiomeBase.SHRUBLAND) {
+            return Biome.SHRUBLAND;
+        } else if (base == BiomeBase.TAIGA) {
+            return Biome.TAIGA;
+        } else if (base == BiomeBase.DESERT) {
+            return Biome.DESERT;
+        } else if (base == BiomeBase.PLAINS) {
+            return Biome.PLAINS;
+        } else if (base == BiomeBase.ICE_DESERT) {
+            return Biome.ICE_DESERT;
+        } else if (base == BiomeBase.TUNDRA) {
+            return Biome.TUNDRA;
+        } else if (base == BiomeBase.HELL) {
+            return Biome.HELL;
+        }
+        return null;
+    }
+
+    /**
+     * Get raw biome temperature (0.0-1.0) at given coordinate
+     *
+     * @param x X-coordinate
+     * @param z Z-coordinate
+     * @return temperature at given coordinate
+     */
+    public double getRawBiomeTemperature(int x, int z) {
+        return biomeTemp[x << 4 | z];
+    }
+
+    /**
+     * Get raw biome rainfall (0.0-1.0) at given coordinate
+     *
+     * @param x X-coordinate
+     * @param z Z-coordinate
+     * @return rainfall at given coordinate
+     */
+    public double getRawBiomeRainfall(int x, int z) {
+        return biomeRain[x << 4 | z];
+    }
+
     /**
      * Get world full time when chunk snapshot was captured
      * @return time in ticks
      */
     public long getCaptureFullTime() {
-        return capture_fulltime;
+        return captureFulltime;
     }
 }

src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -23,6 +23,7 @@ import org.bukkit.util.Vector;
 import org.bukkit.BlockChangeDelegate;
 import org.bukkit.Bukkit;
 import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.ChunkSnapshot;
 import org.bukkit.Location;
 import org.bukkit.TreeType;
 import org.bukkit.World;
@@ -760,4 +761,8 @@ public class CraftWorld implements World {
 
         throw new IllegalArgumentException("Cannot spawn an entity for " + clazz.getName());
     }
+
+    public ChunkSnapshot getEmptyChunkSnapshot(int x, int z, boolean includeBiome, boolean includeBiomeTempRain) {
+        return CraftChunk.getEmptyChunkSnapshot(x, z, this, includeBiome, includeBiomeTempRain);
+    }
 }