Tidying up ImprovedCubicSurfaceExtractor.

library/PolyVoxCore/include/ImprovedCubicSurfaceExtractor.h

@@ -32,11 +32,6 @@ freely, subject to the following restrictions:
 
 namespace PolyVox
 {
-	struct Quad
-	{
-		uint32_t vertices[4];
-	};
-
 	template< template<typename> class VolumeType, typename VoxelType>
 	class ImprovedCubicSurfaceExtractor
 	{
@@ -57,17 +52,23 @@ namespace PolyVox
 			NoOfFaces
 		};
 
+		struct Quad
+		{
+			uint32_t vertices[4];
+		};
+
 	public:
 		ImprovedCubicSurfaceExtractor(VolumeType<VoxelType>* volData, Region region, SurfaceMesh<PositionMaterial>* result, bool bMergeQuads = true);
 
-		void execute();
+		void execute();		
-
-		int32_t addVertex(float fX, float fY, float fZ, uint8_t uMaterial, Array<3, IndexAndMaterial>& existingVertices);
 
 	private:
+		int32_t addVertex(float fX, float fY, float fZ, uint8_t uMaterial, Array<3, IndexAndMaterial>& existingVertices);
+		bool performQuadMerging(std::list<Quad>& quads);
+		bool mergeQuads(Quad& q1, Quad& q2);
+
 		//The volume data and a sampler to access it.
 		VolumeType<VoxelType>* m_volData;
-		typename VolumeType<VoxelType>::Sampler m_sampVolume;
 
 		//Information about the region we are currently processing
 		Region m_regSizeInVoxels;
@@ -75,28 +76,22 @@ namespace PolyVox
 		//The surface patch we are currently filling.
 		SurfaceMesh<PositionMaterial>* m_meshCurrent;
 
-		//Array<4, IndexAndMaterial> m_vertices;
+		//Used to avoid creating duplicate vertices.
 		Array<3, IndexAndMaterial> m_previousSliceVertices;
 		Array<3, IndexAndMaterial> m_currentSliceVertices;
 
-		Array<4, uint8_t> m_faces;
+		//During extraction we create a number of different lists of quads. All the 
-
+		//quads in a given list are in the same plane and facing in the same direction.
 		std::vector< std::list<Quad> > m_vecQuads[NoOfFaces];
 
+		//Controls whether quad merging should be performed. This might be undesirable
+		//is the user needs per-vertex attributes, or to perform per vertex lighting.
 		bool m_bMergeQuads;
 
 		//Although we try to avoid creating multiple vertices at the same location, sometimes this is unavoidable
 		//if they have different materials. For example, four different materials next to each other would mean
 		//four quads (though more triangles) sharing the vertex. As far as I can tell, four is the worst case scenario.
-		static const uint32_t MaxQuadsSharingVertex;
+		static const uint32_t MaxQuadsSharingVertex;		
-
-		////////////////////////////////////////////////////////////////////////////////
-		// Decimation
-		////////////////////////////////////////////////////////////////////////////////
-
-		bool decimate(std::list<Quad>& quads);
-
-		bool mergeQuads(Quad& q1, Quad& q2);
 	};
 }
 

library/PolyVoxCore/include/ImprovedCubicSurfaceExtractor.inl

@@ -35,7 +35,6 @@ namespace PolyVox
 	template< template<typename> class VolumeType, typename VoxelType>
 	ImprovedCubicSurfaceExtractor<VolumeType, VoxelType>::ImprovedCubicSurfaceExtractor(VolumeType<VoxelType>* volData, Region region, SurfaceMesh<PositionMaterial>* result, bool bMergeQuads)
 		:m_volData(volData)
-		,m_sampVolume(volData)
 		,m_regSizeInVoxels(region)
 		,m_meshCurrent(result)
 		,m_bMergeQuads(bMergeQuads)
@@ -58,8 +57,6 @@ namespace PolyVox
 		uint32_t uRegionWidth  = m_regSizeInVoxels.getUpperCorner().getX() - m_regSizeInVoxels.getLowerCorner().getX() + 1;
 		uint32_t uRegionHeight = m_regSizeInVoxels.getUpperCorner().getY() - m_regSizeInVoxels.getLowerCorner().getY() + 1;
 		uint32_t uRegionDepth  = m_regSizeInVoxels.getUpperCorner().getZ() - m_regSizeInVoxels.getLowerCorner().getZ() + 1;
-		m_faces.resize(ArraySizes(uRegionWidth)(uRegionHeight)(uRegionDepth)(NoOfFaces));
-		memset(m_faces.getRawData(), 0x00, m_faces.getNoOfElements() * sizeof(uint8_t)); //Note: hard-coded type uint8_t
 
 		m_vecQuads[NegativeX].resize(m_regSizeInVoxels.getUpperCorner().getX() - m_regSizeInVoxels.getLowerCorner().getX() + 2);
 		m_vecQuads[PositiveX].resize(m_regSizeInVoxels.getUpperCorner().getX() - m_regSizeInVoxels.getLowerCorner().getX() + 2);
@@ -218,7 +215,9 @@ namespace PolyVox
 
 				if(m_bMergeQuads)
 				{
-					while(decimate(listQuads)){}
+					//Repeatedly call this function until it returns
+					//false to indicate nothing more can be done.
+					while(performQuadMerging(listQuads)){}
 				}
 
 				std::list<Quad>::iterator iterEnd = listQuads.end();
@@ -274,7 +273,7 @@ namespace PolyVox
 	}
 
 	template< template<typename> class VolumeType, typename VoxelType>
-	bool ImprovedCubicSurfaceExtractor<VolumeType, VoxelType>::decimate(std::list<Quad>& quads)
+	bool ImprovedCubicSurfaceExtractor<VolumeType, VoxelType>::performQuadMerging(std::list<Quad>& quads)
 	{
 		bool bDidMerge = false;
 		for(std::list<Quad>::iterator outerIter = quads.begin(); outerIter != quads.end(); outerIter++)
@@ -310,6 +309,9 @@ namespace PolyVox
 		//so just check that the first pair or vertices match.
 		if(fabs(m_meshCurrent->getVertices()[q1.vertices[0]].getMaterial() - m_meshCurrent->getVertices()[q2.vertices[0]].getMaterial()) < 0.001)
 		{
+			//Now check whether quad 2 is adjacent to quad one by comparing vertices.
+			//Adjacent quads must share two vertices, and the second quad could be to the
+			//top, bottom, left, of right of the first one. This gives four combinations to test.
 			if((q1.vertices[0] == q2.vertices[1]) && ((q1.vertices[3] == q2.vertices[2])))
 			{
 				q1.vertices[0] = q2.vertices[0];
@@ -336,6 +338,7 @@ namespace PolyVox
 			}
 		}
 		
+		//Quads cannot be merged.
 		return false;
 	}
 }