[Bleeding] Completely fix the tree generation algorithm to make it near identical to vanilla as well as fix potential bugs associated with disappearing saplings.

src/main/java/net/minecraft/server/BlockSapling.java

@@ -2,6 +2,7 @@ package net.minecraft.server;
 
 import java.util.Random;
 // CraftBukkit start
+import org.bukkit.BlockChangeDelegate;
 import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.TreeType;
@@ -43,56 +44,61 @@ public class BlockSapling extends BlockFlower {
     // CraftBukkit - added bonemeal, player and itemstack
     public void grow(World world, int i, int j, int k, Random random, boolean bonemeal, Player player, ItemStack itemstack) {
         int l = world.getData(i, j, k) & 3;
-
-        // CraftBukkit start - records tree generation and calls StructureGrowEvent
-        StructureGrowDelegate delegate = new StructureGrowDelegate(world);
-        TreeType treeType;
         int i1 = 0;
         int j1 = 0;
+        // CraftBukkit start - records tree generation and calls StructureGrowEvent
+        StructureGrowDelegate delegate = new StructureGrowDelegate(world);
+        TreeType treeType = null;
+        TreeGenerator gen = null;
         boolean grownTree = false;
-        boolean megaTree = false;
+        boolean flag = false;
-        // All of these are 'false' because we need the 'raw' calls so the block-delegate works
+
         if (l == 1) {
             treeType = TreeType.REDWOOD;
-            world.setRawTypeId(i, j, k, 0);
+            gen = new WorldGenTaiga2(false);
-            grownTree = new WorldGenTaiga2(false).generate(delegate, random, i, j, k);
         } else if (l == 2) {
             treeType = TreeType.BIRCH;
-            world.setRawTypeId(i, j, k, 0);
+            gen = new WorldGenForest(false);
-            grownTree = new WorldGenForest(false).generate(delegate, random, i, j, k);
         } else if (l == 3) {
-            treeType = TreeType.JUNGLE;
             for (i1 = 0; i1 >= -1; --i1) {
                 for (j1 = 0; j1 >= -1; --j1) {
                     if (world.getTypeId(i + i1, j, k + j1) == this.id && world.getTypeId(i + i1 + 1, j, k + j1) == this.id && world.getTypeId(i + i1, j, k + j1 + 1) == this.id && world.getTypeId(i + i1 + 1, j, k + j1 + 1) == this.id) {
-                        world.setRawTypeId(i + i1, j, k + j1, 0);
+                        treeType = TreeType.JUNGLE;
-                        world.setRawTypeId(i + i1 + 1, j, k + j1, 0);
+                        gen = new WorldGenMegaTree(false, 10 + random.nextInt(20), 3, 3);
-                        world.setRawTypeId(i + i1, j, k + j1 + 1, 0);
+                        flag = true;
-                        world.setRawTypeId(i + i1 + 1, j, k + j1 + 1, 0);
-                        grownTree = new WorldGenMegaTree(false, 10 + random.nextInt(20), 3, 3).generate(delegate, random, i + i1, j, k + j1);
-                        megaTree = true;
                         break;
                     }
                 }
+
+                if (gen != null) {
+                    break;
+                }
             }
-            if (!grownTree) {
+
+            if (gen == null) {
                 j1 = 0;
                 i1 = 0;
-                world.setRawTypeId(i, j, k, 0);
+                treeType = TreeType.TREE;
-                grownTree = new WorldGenTrees(false, 4 + random.nextInt(7), 3, 3, false).generate(delegate, random, i, j, k);
+                gen = new WorldGenTrees(false, 4 + random.nextInt(7), 3, 3, false);
             }
         } else {
+            treeType = TreeType.TREE;
+            gen = new WorldGenTrees(false);
             if (random.nextInt(10) == 0) {
                 treeType = TreeType.BIG_TREE;
-                world.setRawTypeId(i, j, k, 0);
+                gen = new WorldGenBigTree(false);
-                grownTree = new WorldGenBigTree(false).generate(delegate, random, i, j, k);
-            } else {
-                treeType = TreeType.TREE;
-                world.setRawTypeId(i, j, k, 0);
-                grownTree = new WorldGenTrees(false).generate(delegate, random, i, j, k);
             }
         }
 
+        if (flag) {
+            world.setRawTypeId(i + i1, j, k + j1, 0);
+            world.setRawTypeId(i + i1 + 1, j, k + j1, 0);
+            world.setRawTypeId(i + i1, j, k + j1 + 1, 0);
+            world.setRawTypeId(i + i1 + 1, j, k + j1 + 1, 0);
+        } else {
+            world.setRawTypeId(i, j, k, 0);
+        }
+        grownTree = gen.generate(delegate, random, i + i1, j, k + j1);
         if (grownTree) {
             Location location = new Location(world.getWorld(), i, j, k);
             StructureGrowEvent event = new StructureGrowEvent(location, treeType, bonemeal, player, delegate.getBlocks());
@@ -108,10 +114,8 @@ public class BlockSapling extends BlockFlower {
                 }
             }
         }
-
         if (!grownTree) {
-            if (megaTree) {
+            if (flag) {
-                // CraftBukkit end
                 world.setRawTypeIdAndData(i + i1, j, k + j1, this.id, l);
                 world.setRawTypeIdAndData(i + i1 + 1, j, k + j1, this.id, l);
                 world.setRawTypeIdAndData(i + i1, j, k + j1 + 1, this.id, l);
@@ -120,9 +124,19 @@ public class BlockSapling extends BlockFlower {
                 world.setRawTypeIdAndData(i, j, k, this.id, l);
             }
         }
+        // CraftBukkit end
     }
 
     protected int getDropData(int i) {
         return i & 3;
     }
+
+    // CraftBukkit start
+    interface TreeGenerator {
+
+        public boolean a(World world, Random random, int i, int j, int k);
+
+        public boolean generate(BlockChangeDelegate world, Random random, int i, int j, int k);
+    }
+    // CraftBukkit end
 }

src/main/java/net/minecraft/server/WorldGenBigTree.java

@@ -4,7 +4,7 @@ import java.util.Random;
 
 import org.bukkit.BlockChangeDelegate; // CraftBukkit
 
-public class WorldGenBigTree extends WorldGenerator {
+public class WorldGenBigTree extends WorldGenerator implements BlockSapling.TreeGenerator { // CraftBukkit add interface
 
     static final byte[] a = new byte[] { (byte) 2, (byte) 0, (byte) 0, (byte) 1, (byte) 2, (byte) 1};
     Random b = new Random();

src/main/java/net/minecraft/server/WorldGenForest.java

@@ -4,7 +4,7 @@ import java.util.Random;
 
 import org.bukkit.BlockChangeDelegate; // CraftBukkit
 
-public class WorldGenForest extends WorldGenerator {
+public class WorldGenForest extends WorldGenerator implements BlockSapling.TreeGenerator { // CraftBukkit add interface
 
     public WorldGenForest(boolean flag) {
         super(flag);

src/main/java/net/minecraft/server/WorldGenMegaTree.java

@@ -4,7 +4,7 @@ import java.util.Random;
 
 import org.bukkit.BlockChangeDelegate; // CraftBukkit
 
-public class WorldGenMegaTree extends WorldGenerator {
+public class WorldGenMegaTree extends WorldGenerator implements BlockSapling.TreeGenerator { // CraftBukkit add interface
 
     private final int a;
     private final int b;

src/main/java/net/minecraft/server/WorldGenTaiga1.java

@@ -4,7 +4,7 @@ import java.util.Random;
 
 import org.bukkit.BlockChangeDelegate; // CraftBukkit
 
-public class WorldGenTaiga1 extends WorldGenerator {
+public class WorldGenTaiga1 extends WorldGenerator implements BlockSapling.TreeGenerator { // CraftBukkit add interface
 
     public WorldGenTaiga1() {}
 

src/main/java/net/minecraft/server/WorldGenTaiga2.java

@@ -4,7 +4,7 @@ import java.util.Random;
 
 import org.bukkit.BlockChangeDelegate; // CraftBukkit
 
-public class WorldGenTaiga2 extends WorldGenerator {
+public class WorldGenTaiga2 extends WorldGenerator implements BlockSapling.TreeGenerator { // CraftBukkit add interface
 
     public WorldGenTaiga2(boolean flag) {
         super(flag);

src/main/java/net/minecraft/server/WorldGenTrees.java

@@ -4,7 +4,7 @@ import java.util.Random;
 
 import org.bukkit.BlockChangeDelegate; // CraftBukkit
 
-public class WorldGenTrees extends WorldGenerator {
+public class WorldGenTrees extends WorldGenerator implements BlockSapling.TreeGenerator { // CraftBukkit add interface
 
     private final int a;
     private final boolean b;