From c1f010298988666707b32154846543ba8f363a07 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.


diff --git a/src/main/java/net/minecraft/server/WorldGenForestTree.java b/src/main/java/net/minecraft/server/WorldGenForestTree.java
index 2653bd8..dd9e5b6 100644
--- a/src/main/java/net/minecraft/server/WorldGenForestTree.java
+++ b/src/main/java/net/minecraft/server/WorldGenForestTree.java
@@ -123,7 +123,15 @@ public class WorldGenForestTree extends WorldGenTreeAbstract {
                                 int k2;
 
                                 for (k2 = 0; k2 < j2; ++k2) {
-                                    this.a(world, new BlockPosition(blockposition.getX() + l1, k1 - k2 - 1, blockposition.getZ() + i2), Blocks.LOG2, EnumLogVariant.DARK_OAK.a() - 4);
+                                    // Spigot start
+                                    BlockPosition position = new BlockPosition(blockposition.getX() + l1, k1 - k2 - 1, blockposition.getZ() + i2);
+                                    Block bl = world.getType(position).getBlock();
+
+                                    if (bl.getMaterial() == Material.AIR || bl.getMaterial() == Material.LEAVES)
+                                    {
+                                        this.a(world, position, Blocks.LOG2, EnumLogVariant.DARK_OAK.a() - 4);
+                                    }
+                                    // Spigot end
                                 }
 
                                 int l2;
-- 
2.1.0