From eb9c8822d9bcf55bbc0522eee8ef9953b60ba4ce Mon Sep 17 00:00:00 2001
From: SenseiKiwi <senseikiwi@server.fake>
Date: Wed, 24 Jul 2013 15:34:21 -0400
Subject: [PATCH] Fixed NullPointerException in yCoordHelper

I believe I've fixed the cause of a NullPointerException that some
players have been experiencing. It seems to have been caused by
unregistered block IDs being present in Limbo. Possibly because people
removed mods and they had generated structures in Limbo. Or the players
had placed blocks and then removed the mods, or changed block IDs
around.

This fixes issue #47.
---
 .../mod_pocketDim/helpers/yCoordHelper.java   | 91 ++++++++++---------
 1 file changed, 48 insertions(+), 43 deletions(-)

diff --git a/StevenDimDoors/mod_pocketDim/helpers/yCoordHelper.java b/StevenDimDoors/mod_pocketDim/helpers/yCoordHelper.java
index 66d0babc..7b656230 100644
--- a/StevenDimDoors/mod_pocketDim/helpers/yCoordHelper.java
+++ b/StevenDimDoors/mod_pocketDim/helpers/yCoordHelper.java
@@ -2,66 +2,71 @@ package StevenDimDoors.mod_pocketDim.helpers;
 
 import StevenDimDoors.mod_pocketDim.LinkData;
 import net.minecraft.block.Block;
+import net.minecraft.block.material.Material;
 import net.minecraft.world.World;
 import net.minecraft.world.chunk.Chunk;
 
 
 public class yCoordHelper 
 {
+	private static final int MAXIMUM_UNCOVERED_Y = 245;
+	
 	public static int getFirstUncovered(LinkData pointerLink)
 	{
-		return yCoordHelper.getFirstUncovered(pointerLink.destDimID, pointerLink.destXCoord,pointerLink.destYCoord, pointerLink.destZCoord);
+		return yCoordHelper.getFirstUncovered(
+				pointerLink.destDimID,
+				pointerLink.destXCoord,
+				pointerLink.destYCoord,
+				pointerLink.destZCoord);
 	}
+	
 	public static int getFirstUncovered(int worldID, int x, int yStart, int z)
 	{
-		if(dimHelper.getWorld(worldID)==null||dimHelper.getWorld(worldID).provider==null)
+		if (dimHelper.getWorld(worldID) == null ||
+			dimHelper.getWorld(worldID).provider == null)
 	   	{
 	   		dimHelper.initDimension(worldID);
 	   	}
 		
-		return yCoordHelper.getFirstUncovered(dimHelper.getWorld(worldID),x,yStart,z);
+		return yCoordHelper.getFirstUncovered(dimHelper.getWorld(worldID), x, yStart, z);
 	}
+	
 	public static int getFirstUncovered(World world, int x, int yStart, int z)
 	{
-		int yCoord=yStart;
-	   	
-			Chunk chunk = world.getChunkProvider().loadChunk(x >> 4, z >> 4);
-			
-			int xC=(x % 16)< 0 ? (x % 16)+16 : (x % 16);
-			int yC=yCoord;
-			int zC=(z % 16)< 0 ? (z % 16)+16 : (z % 16);
-			
-			
-			boolean flag=false;
-			
-			do
-			{
-				flag=false;
-				if(yC>0&&chunk.getBlockID(xC, yC-1, zC)!=0)
-				{
-					if(!Block.blocksList[chunk.getBlockID(xC, yC-1, zC)].blockMaterial.isReplaceable()||Block.blocksList[chunk.getBlockID(xC, yC-1, zC)].blockMaterial.isLiquid())
-					{
-						
-							flag=true;
-						
-					}
-				}
-				
-				 if(yC>0&&chunk.getBlockID(xC, yC, zC)!=0)
-				{
-					if(!Block.blocksList[chunk.getBlockID(xC, yC, zC)].blockMaterial.isReplaceable()||Block.blocksList[chunk.getBlockID(xC, yC, zC)].blockMaterial.isLiquid())
-					{
-						
-							flag=true;
-						
-					}
-				}
-				
-				yC++;
-			}
-			while(flag&&yC<245);
-			
-			
-			return yC-1;
+		Chunk chunk = world.getChunkProvider().loadChunk(x >> 4, z >> 4);
+
+		int localX = x < 0 ? (x % 16) + 16 : (x % 16);
+		int localZ = z < 0 ? (z % 16) + 16 : (z % 16);
+		int height = MAXIMUM_UNCOVERED_Y;  //world.getHeight();
+		int y;
+		
+		boolean covered = true;
+		for (y = yStart; y < height && covered; y++)
+		{
+			covered = IsCoveredBlock(chunk, localX, y - 1, localZ) || IsCoveredBlock(chunk, localX, y, localZ);
+		}
+
+		return y;
+	}
+	
+	public static boolean IsCoveredBlock(Chunk chunk, int localX, int y, int localZ)
+	{
+		int blockID;
+		Block block;
+		Material material;
+		
+		if (y < 0)
+			return false;
+		
+		blockID = chunk.getBlockID(localX, y, localZ);
+		if (blockID == 0)
+			return false;
+
+		block = Block.blocksList[blockID];
+		if (block == null)
+			return false;
+		
+		material = block.blockMaterial;
+		return (!material.isLiquid() && !material.isReplaceable());
 	}
 }
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