From cc1aa8a514b69525ba97af97d43d7cc29ed6d8d4 Mon Sep 17 00:00:00 2001
From: David Williams <david@david-williams.info>
Date: Sun, 12 Sep 2010 21:10:15 +0000
Subject: [PATCH] Fix for broken moveNegative...() sampler functions. Fixed bug
 in surface extractor causing divide by zero and/or infinite vertices.

---
 library/PolyVoxCore/include/SurfaceExtractor.inl |  6 ++++++
 library/PolyVoxCore/include/VolumeSampler.inl    | 12 ++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/library/PolyVoxCore/include/SurfaceExtractor.inl b/library/PolyVoxCore/include/SurfaceExtractor.inl
index 983cf0bf..606a45aa 100644
--- a/library/PolyVoxCore/include/SurfaceExtractor.inl
+++ b/library/PolyVoxCore/include/SurfaceExtractor.inl
@@ -467,6 +467,8 @@ namespace PolyVox
 					surfaceVertex.setOnGeometryEdgePosZ(isPosZEdge);
 					uint32_t uLastVertexIndex = m_meshCurrent->addVertex(surfaceVertex);
 					m_pCurrentVertexIndicesX[uXVolSpace - m_regSizeInVoxels.getLowerCorner().getX()][uYVolSpace - m_regSizeInVoxels.getLowerCorner().getY()] = uLastVertexIndex;
+
+					m_sampVolume.moveNegativeX();
 				}
 				if (edgeTable[iCubeIndex] & 8)
 				{
@@ -495,6 +497,8 @@ namespace PolyVox
 					surfaceVertex.setOnGeometryEdgePosZ(isPosZEdge);
 					uint32_t uLastVertexIndex = m_meshCurrent->addVertex(surfaceVertex);
 					m_pCurrentVertexIndicesY[uXVolSpace - m_regSizeInVoxels.getLowerCorner().getX()][uYVolSpace - m_regSizeInVoxels.getLowerCorner().getY()] = uLastVertexIndex;
+
+					m_sampVolume.moveNegativeY();
 				}
 				if (edgeTable[iCubeIndex] & 256)
 				{
@@ -523,6 +527,8 @@ namespace PolyVox
 					surfaceVertex.setOnGeometryEdgePosZ(isPosZEdge);
 					uint32_t uLastVertexIndex = m_meshCurrent->addVertex(surfaceVertex);
 					m_pCurrentVertexIndicesZ[uXVolSpace - m_regSizeInVoxels.getLowerCorner().getX()][uYVolSpace - m_regSizeInVoxels.getLowerCorner().getY()] = uLastVertexIndex;
+
+					m_sampVolume.moveNegativeZ();
 				}
 			}//For each cell
 		}
diff --git a/library/PolyVoxCore/include/VolumeSampler.inl b/library/PolyVoxCore/include/VolumeSampler.inl
index dafe2a20..1f5b817c 100644
--- a/library/PolyVoxCore/include/VolumeSampler.inl
+++ b/library/PolyVoxCore/include/VolumeSampler.inl
@@ -228,11 +228,11 @@ namespace PolyVox
 	template <typename VoxelType>
 	void VolumeSampler<VoxelType>::moveNegativeX(void)
 	{
-		//Note the *post* increament here
+		//Note the *post* decreament here
 		if((mXPosInVolume--) % mVolume->m_uBlockSideLength != 0)
 		{
 			//No need to compute new block.
-			++mCurrentVoxel;			
+			--mCurrentVoxel;			
 		}
 		else
 		{
@@ -244,11 +244,11 @@ namespace PolyVox
 	template <typename VoxelType>
 	void VolumeSampler<VoxelType>::moveNegativeY(void)
 	{
-		//Note the *post* increament here
+		//Note the *post* decreament here
 		if((mYPosInVolume--) % mVolume->m_uBlockSideLength != 0)
 		{
 			//No need to compute new block.
-			mCurrentVoxel += mVolume->m_uBlockSideLength;
+			mCurrentVoxel -= mVolume->m_uBlockSideLength;
 		}
 		else
 		{
@@ -260,11 +260,11 @@ namespace PolyVox
 	template <typename VoxelType>
 	void VolumeSampler<VoxelType>::moveNegativeZ(void)
 	{
-		//Note the *post* increament here
+		//Note the *post* decreament here
 		if((mZPosInVolume--) % mVolume->m_uBlockSideLength != 0)
 		{
 			//No need to compute new block.
-			mCurrentVoxel += mVolume->m_uBlockSideLength * mVolume->m_uBlockSideLength;
+			mCurrentVoxel -= mVolume->m_uBlockSideLength * mVolume->m_uBlockSideLength;
 		}
 		else
 		{