From fc6f0c098daa08c47192a1a255d1f5731682feb4 Mon Sep 17 00:00:00 2001
From: Thinkofdeath <thethinkofdeath@gmail.com>
Date: Mon, 20 Jan 2014 20:42:28 +0000
Subject: [PATCH] Don't let trees replace any block when growing


diff --git a/src/main/java/net/minecraft/server/WorldGenForestTree.java b/src/main/java/net/minecraft/server/WorldGenForestTree.java
index 71ce973..caaac9a 100644
--- a/src/main/java/net/minecraft/server/WorldGenForestTree.java
+++ b/src/main/java/net/minecraft/server/WorldGenForestTree.java
@@ -132,7 +132,12 @@ public class WorldGenForestTree extends WorldGenTreeAbstract implements BlockSap
                                 int k3;
 
                                 for (k3 = 0; k3 < j3; ++k3) {
-                                    this.setTypeAndData(world, i + l2, k2 - k3 - 1, k + i3, Blocks.LOG2, 1);
+                                    Block block = world.getType(i + l2, k2 - k3 - 1, k + i3);
+
+                                    if (block.getMaterial() == Material.AIR || block.getMaterial() == Material.LEAVES)
+                                    {
+                                        this.setTypeAndData(world, i + l2, k2 - k3 - 1, k + i3, Blocks.LOG2, 1);
+                                    }
                                 }
 
                                 int l3;
-- 
1.8.5.2.msysgit.0