#pragma region License
/******************************************************************************
This file is part of the PolyVox library
Copyright (C) 2006  David Williams

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
******************************************************************************/
#pragma endregion

#ifndef __PolyVox_SurfaceExtractor_H__
#define __PolyVox_SurfaceExtractor_H__

#pragma region Headers
#include "PolyVoxForwardDeclarations.h"
#include "VolumeSampler.h"

#include "PolyVoxImpl/TypeDef.h"
#include "PolyVoxImpl/CPlusPlusZeroXSupport.h"
#pragma endregion

namespace PolyVox
{
	class POLYVOXCORE_API SurfaceExtractor
	{
	public:
		SurfaceExtractor(Volume<uint8_t>& volData);

		uint8_t getLodLevel(void);

		void setLodLevel(uint8_t uLodLevel);

		POLYVOX_SHARED_PTR<IndexedSurfacePatch> extractSurfaceForRegion(Region region);

	private:
		//Extract the surface for a particular LOD level
		template<uint8_t uLodLevel>
		void extractSurfaceImpl(void);

		//Compute the cell bitmask for a particular slice in z.
		template<bool isPrevZAvail, uint8_t uLodLevel>
		uint32_t computeBitmaskForSlice(void);

		//Compute the cell bitmask for a given cell.
		template<bool isPrevXAvail, bool isPrevYAvail, bool isPrevZAvail, uint8_t uLodLevel>
		void computeBitmaskForCell(void);

		//Use the cell bitmasks to generate all the vertices needed for that slice
		void generateVerticesForSlice();

		//Use the cell bitmasks to generate all the indices needed for that slice
		void generateIndicesForSlice();

		//Converts a position into an index for accessing scratch areas.
		inline uint32_t getIndex(uint32_t x, uint32_t y)
		{
			return x + (y * m_uScratchPadWidth);
		}

		//The lod level can step size.
		uint8_t m_uLodLevel;
		uint8_t m_uStepSize;

		//The volume data and a sampler to access it.
		Volume<uint8_t> m_volData;
		VolumeSampler<uint8_t> m_sampVolume;

		//Cell bitmasks for the current and previous slices.
		uint8_t* m_pPreviousBitmask;
		uint8_t* m_pCurrentBitmask;

		//Used to keep track of where generated vertices have been placed.
		int32_t* m_pPreviousVertexIndicesX;
		int32_t* m_pPreviousVertexIndicesY; 
		int32_t* m_pPreviousVertexIndicesZ; 
		int32_t* m_pCurrentVertexIndicesX; 
		int32_t* m_pCurrentVertexIndicesY; 
		int32_t* m_pCurrentVertexIndicesZ;

		//Holds a position in volume space.
		uint16_t uXVolSpace;
		uint16_t uYVolSpace;
		uint16_t uZVolSpace;

		//Holds a position in region space.
		uint16_t uXRegSpace;
		uint16_t uYRegSpace;
		uint16_t uZRegSpace;

		//Used to return the number of cells in a slice which contain triangles.
		uint32_t m_uNoOfOccupiedCells;

		//The surface patch we are currently filling.
		IndexedSurfacePatch* m_ispCurrent;

		//Information about the region we are currently processing
		Region m_regInputCropped;
		Region m_regInputUncropped;
		Region m_regVolumeCropped;
		Region m_regSlicePrevious;
		Region m_regSliceCurrent;

		//Store the width and height because they are frequently
		//used and have some overhead to compute.
		uint16_t m_uRegionWidth;
		uint16_t m_uRegionHeight;

		//These are used in several places so best stored.
		uint16_t m_uScratchPadWidth;
		uint16_t m_uScratchPadHeight;		
	};
}

#endif