/*
Free Asset Import Library (ASSIMP)
----------------------------------------------------------------------

Copyright (c) 2006-2008, ASSIMP Development Team
All rights reserved.

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  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
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* Neither the name of the ASSIMP team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the ASSIMP Development Team.

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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
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*/


/** @file Implementation of the SplitLargeMeshes postprocessing step
*/
#include "SplitLargeMeshes.h"
#include "../include/aiPostProcess.h"
#include "../include/aiMesh.h"
#include "../include/aiScene.h"

using namespace Assimp;

/*static*/ unsigned int SplitLargeMeshesProcess_Triangle::LIMIT = AI_SLM_DEFAULT_MAX_TRIANGLES;
/*static*/ unsigned int SplitLargeMeshesProcess_Vertex::LIMIT = AI_SLM_DEFAULT_MAX_VERTICES;

extern "C" {

// ------------------------------------------------------------------------------------------------
aiReturn aiSetVertexSplitLimit(unsigned int pLimit)
{
	if (0 == pLimit)
	{
		SplitLargeMeshesProcess_Vertex::LIMIT = 0xFFFFFFFF;
		return AI_FAILURE;
	}

	SplitLargeMeshesProcess_Vertex::LIMIT = pLimit;
	return AI_SUCCESS;
}
// ------------------------------------------------------------------------------------------------
aiReturn aiSetTriangleSplitLimit(unsigned int pLimit)
{
	if (0 == pLimit)
	{
		SplitLargeMeshesProcess_Triangle::LIMIT = 0xFFFFFFFF;
		return AI_FAILURE;
	}

	SplitLargeMeshesProcess_Triangle::LIMIT = pLimit;
	return AI_SUCCESS;
}
}; //! extern "C"

// ------------------------------------------------------------------------------------------------
SplitLargeMeshesProcess_Triangle::SplitLargeMeshesProcess_Triangle()
	{
		// nothing to do here
	}
// ------------------------------------------------------------------------------------------------
SplitLargeMeshesProcess_Triangle::~SplitLargeMeshesProcess_Triangle()
	{
	// nothing to do here
	}
// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool SplitLargeMeshesProcess_Triangle::IsActive( unsigned int pFlags) const
{
	return (pFlags & aiProcess_SplitLargeMeshes) != 0 && (0xFFFFFFFF != LIMIT);
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void SplitLargeMeshesProcess_Triangle::Execute( aiScene* pScene)
{
	std::vector<std::pair<aiMesh*, unsigned int> > avList;

	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
		this->SplitMesh(a, pScene->mMeshes[a],avList);

	if (avList.size() != pScene->mNumMeshes)
	{
		// it seems something has been splitted. rebuild the mesh list
		delete[] pScene->mMeshes;
		pScene->mNumMeshes = avList.size();
		pScene->mMeshes = new aiMesh*[avList.size()];

		for (unsigned int i = 0; i < avList.size();++i)
			pScene->mMeshes[i] = avList[i].first;

		// now we need to update all nodes
		this->UpdateNode(pScene->mRootNode,avList);
	}
	return;
}
// ------------------------------------------------------------------------------------------------
// Update a node after some meshes have been split
void SplitLargeMeshesProcess_Triangle::UpdateNode(aiNode* pcNode,
	const std::vector<std::pair<aiMesh*, unsigned int> >& avList)
{
	// for every index in out list build a new entry
	std::vector<unsigned int> aiEntries;
	aiEntries.reserve(pcNode->mNumMeshes + 1);
	for (unsigned int i = 0; i < pcNode->mNumMeshes;++i)
	{
		for (unsigned int a = 0; a < avList.size();++a)
		{
			if (avList[a].second == pcNode->mMeshes[i])
			{
				aiEntries.push_back(a);
			}
		}
	}

	// now build the new list
	delete pcNode->mMeshes;
	pcNode->mNumMeshes = aiEntries.size();
	pcNode->mMeshes = new unsigned int[pcNode->mNumMeshes];

	for (unsigned int b = 0; b < pcNode->mNumMeshes;++b)
		pcNode->mMeshes[b] = aiEntries[b];

	// recusively update all other nodes
	for (unsigned int i = 0; i < pcNode->mNumChildren;++i)
	{
		UpdateNode ( pcNode->mChildren[i], avList );
	}
	return;
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void SplitLargeMeshesProcess_Triangle::SplitMesh(
	unsigned int a,
	aiMesh* pMesh,
	std::vector<std::pair<aiMesh*, unsigned int> >& avList)
{
	if (pMesh->mNumFaces > LIMIT)
	{
		// we need to split this mesh into sub meshes
		// determine the size of a submesh
		const unsigned int iSubMeshes = (pMesh->mNumFaces / LIMIT) + 1;

		const unsigned int iOutFaceNum = pMesh->mNumFaces / iSubMeshes;
		const unsigned int iOutVertexNum = iOutFaceNum * 3;

		// now generate all submeshes
		for (unsigned int i = 0; i < iSubMeshes;++i)
		{
			aiMesh* pcMesh			= new aiMesh;			
			pcMesh->mNumFaces		= iOutFaceNum;
			pcMesh->mMaterialIndex	= pMesh->mMaterialIndex;

			if (i == iSubMeshes-1)
			{
				pcMesh->mNumFaces = iOutFaceNum + (
					pMesh->mNumFaces - iOutFaceNum * iSubMeshes);
			}
			// copy the list of faces
			pcMesh->mFaces = new aiFace[pcMesh->mNumFaces];

			const unsigned int iBase = iOutFaceNum * i;

			// get the total number of indices
			unsigned int iCnt = 0;
			for (unsigned int p = iBase; p < pcMesh->mNumFaces + iBase;++p)
			{
				iCnt += pMesh->mFaces[p].mNumIndices;
			}
			pcMesh->mNumVertices = iCnt;

			// allocate storage
			if (pMesh->mVertices != NULL)
				pcMesh->mVertices = new aiVector3D[iCnt];

			if (pMesh->HasNormals())
				pcMesh->mNormals = new aiVector3D[iCnt];

			if (pMesh->HasTangentsAndBitangents())
			{
				pcMesh->mTangents = new aiVector3D[iCnt];
				pcMesh->mBitangents = new aiVector3D[iCnt];
			}

			// texture coordinates
			for (unsigned int c = 0;  c < AI_MAX_NUMBER_OF_TEXTURECOORDS;++c)
			{
				pcMesh->mNumUVComponents[c] = pMesh->mNumUVComponents[c];
				if (pMesh->HasTextureCoords( c))
				{
					pcMesh->mTextureCoords[c] = new aiVector3D[iCnt];
				}
			}

			// vertex colors
			for (unsigned int c = 0;  c < AI_MAX_NUMBER_OF_COLOR_SETS;++c)
			{
				if (pMesh->HasVertexColors( c))
				{
					pcMesh->mColors[c] = new aiColor4D[iCnt];
				}
			}

			// (we will also need to copy the array of indices)
			unsigned int iCurrent = 0;
			for (unsigned int p = 0; p < pcMesh->mNumFaces;++p)
			{
				pcMesh->mFaces[p].mNumIndices = 3;
				// allocate a new array
				const unsigned int iTemp = p + iBase;
				const unsigned int iNumIndices = pMesh->mFaces[iTemp].mNumIndices;

				// setup face type and number of indices
				pcMesh->mFaces[p].mNumIndices = iNumIndices;
				unsigned int* pi = pMesh->mFaces[iTemp].mIndices;

				pcMesh->mFaces[p].mIndices = new unsigned int[iNumIndices];

				// and copy the contents of the old array, offset by current base
				for (unsigned int v = 0; v < iNumIndices;++v)
				{
					unsigned int iIndex = pMesh->mFaces[iTemp].mIndices[v];
					unsigned int iIndexOut = iCurrent++;
					pcMesh->mFaces[p].mIndices[v] = iIndexOut;

					// copy positions
					if (pMesh->mVertices != NULL)
					{
						pcMesh->mVertices[iIndexOut] = pMesh->mVertices[iIndex];
					}

					// copy normals
					if (pMesh->HasNormals())
					{
						pcMesh->mNormals[iIndexOut] = pMesh->mNormals[iIndex];
					}

					// copy tangents/bitangents
					if (pMesh->HasTangentsAndBitangents())
					{
						pcMesh->mTangents[iIndexOut] = pMesh->mTangents[iIndex];
						pcMesh->mBitangents[iIndexOut] = pMesh->mBitangents[iIndex];
					}

					// texture coordinates
					for (unsigned int c = 0;  c < AI_MAX_NUMBER_OF_TEXTURECOORDS;++c)
					{
						if (pMesh->HasTextureCoords( c))
						{
							pcMesh->mTextureCoords[c][iIndexOut] = pMesh->mTextureCoords[c][iIndex];
						}
					}
					// vertex colors 
					for (unsigned int c = 0;  c < AI_MAX_NUMBER_OF_COLOR_SETS;++c)
					{
						if (pMesh->HasVertexColors( c))
						{
							pcMesh->mColors[c][iIndexOut] = pMesh->mColors[c][iIndex];
						}
					}
				}
			}

			// add the newly created mesh to the list
			avList.push_back(std::pair<aiMesh*, unsigned int>(pcMesh,a));
		}

		// now delete the old mesh data
		delete pMesh;
	}
	else avList.push_back(std::pair<aiMesh*, unsigned int>(pMesh,a));
	return;
}
// ------------------------------------------------------------------------------------------------
SplitLargeMeshesProcess_Vertex::SplitLargeMeshesProcess_Vertex()
	{
		// nothing to do here
	}
// ------------------------------------------------------------------------------------------------
SplitLargeMeshesProcess_Vertex::~SplitLargeMeshesProcess_Vertex()
	{
	// nothing to do here
	}
// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool SplitLargeMeshesProcess_Vertex::IsActive( unsigned int pFlags) const
{
	return (pFlags & aiProcess_SplitLargeMeshes) != 0 && (0xFFFFFFFF != LIMIT);
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void SplitLargeMeshesProcess_Vertex::Execute( aiScene* pScene)
{
	std::vector<std::pair<aiMesh*, unsigned int> > avList;

	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
		this->SplitMesh(a, pScene->mMeshes[a],avList);

	if (avList.size() != pScene->mNumMeshes)
	{
		// it seems something has been splitted. rebuild the mesh list
		delete[] pScene->mMeshes;
		pScene->mNumMeshes = avList.size();
		pScene->mMeshes = new aiMesh*[avList.size()];

		for (unsigned int i = 0; i < avList.size();++i)
			pScene->mMeshes[i] = avList[i].first;

		// now we need to update all nodes
		SplitLargeMeshesProcess_Triangle::UpdateNode(pScene->mRootNode,avList);
	}
	return;
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void SplitLargeMeshesProcess_Vertex::SplitMesh(
	unsigned int a,
	aiMesh* pMesh,
	std::vector<std::pair<aiMesh*, unsigned int> >& avList)
{
	if (pMesh->mNumVertices > SplitLargeMeshesProcess_Vertex::LIMIT)
	{
		// we need to split this mesh into sub meshes
		// determine the estimated size of a submesh
		// (this could be too large. Max waste is a single digit percentage)
		const unsigned int iSubMeshes = (pMesh->mNumVertices / SplitLargeMeshesProcess_Vertex::LIMIT) + 1;
		const unsigned int iOutVertexNum2 = pMesh->mNumVertices /iSubMeshes;

		// create a std::vector<unsigned int> to indicate which vertices
		// have already been copied
		std::vector<unsigned int> avWasCopied;
		avWasCopied.resize(pMesh->mNumVertices,0xFFFFFFFF);

		// try to find a good estimate for the number of output faces
		// per mesh. Add 12.5% as buffer
		unsigned int iEstimatedSize = pMesh->mNumFaces / iSubMeshes;
		iEstimatedSize += iEstimatedSize >> 3;

		// now generate all submeshes
		unsigned int iBase = 0;
		while (true)
		{
			const unsigned int iOutVertexNum = SplitLargeMeshesProcess_Vertex::LIMIT;

			aiMesh* pcMesh			= new aiMesh;			
			pcMesh->mNumVertices	= 0;
			pcMesh->mMaterialIndex	= pMesh->mMaterialIndex;

			// clear the temporary helper array
			if (0 != iBase)
			{
				memset(&avWasCopied[0],0xFF,pMesh->mNumVertices * sizeof(unsigned int));
			}

			// output vectors
			std::vector<aiFace> vFaces;

			// reserve enough storage for most cases
			if (pMesh->HasPositions())
			{
				pcMesh->mVertices = new aiVector3D[iOutVertexNum];
			}
			if (pMesh->HasNormals())
			{
				pcMesh->mNormals = new aiVector3D[iOutVertexNum];
			}
			if (pMesh->HasTangentsAndBitangents())
			{
				pcMesh->mTangents = new aiVector3D[iOutVertexNum];
				pcMesh->mBitangents = new aiVector3D[iOutVertexNum];
			}
			for (unsigned int c = 0; pMesh->HasVertexColors(c);++c)
			{
				pcMesh->mColors[c] = new aiColor4D[iOutVertexNum];
			}
			for (unsigned int c = 0; pMesh->HasTextureCoords(c);++c)
			{
				pcMesh->mNumUVComponents[c] = pMesh->mNumUVComponents[c];
				pcMesh->mTextureCoords[c] = new aiVector3D[iOutVertexNum];
			}
			vFaces.reserve(iEstimatedSize);

			// (we will also need to copy the array of indices)
			while (iBase < pMesh->mNumFaces)
			{
				// allocate a new array
				const unsigned int iNumIndices = pMesh->mFaces[iBase].mNumIndices;

				// doesn't catch degenerates but is quite fast
				unsigned int iNeed = 0;
				for (unsigned int v = 0; v < iNumIndices;++v)
				{
					unsigned int iIndex = pMesh->mFaces[iBase].mIndices[v];

					// check whether we do already have this vertex
					if (0xFFFFFFFF == avWasCopied[iIndex])
					{
						iNeed++; 
					}
				}
				if (pcMesh->mNumVertices + iNeed > iOutVertexNum)
				{
					// don't use this face
					break;
				}

				vFaces.push_back(aiFace());
				aiFace& rFace = vFaces.back();

				// setup face type and number of indices
				rFace.mNumIndices = iNumIndices;
				rFace.mIndices = new unsigned int[iNumIndices];

				// and copy the contents of the old array, offset by current base
				for (unsigned int v = 0; v < iNumIndices;++v)
				{
					unsigned int iIndex = pMesh->mFaces[iBase].mIndices[v];

					// check whether we do already have this vertex
					if (0xFFFFFFFF != avWasCopied[iIndex])
					{
						rFace.mIndices[v] = avWasCopied[iIndex];
						continue;
					}

					// copy positions
					pcMesh->mVertices[pcMesh->mNumVertices] = (pMesh->mVertices[iIndex]);

					// copy normals
					if (pMesh->HasNormals())
					{
						pcMesh->mNormals[pcMesh->mNumVertices] = (pMesh->mNormals[iIndex]);
					}

					// copy tangents/bitangents
					if (pMesh->HasTangentsAndBitangents())
					{
						pcMesh->mTangents[pcMesh->mNumVertices] = (pMesh->mTangents[iIndex]);
						pcMesh->mBitangents[pcMesh->mNumVertices] = (pMesh->mBitangents[iIndex]);
					}

					// texture coordinates
					for (unsigned int c = 0;  c < AI_MAX_NUMBER_OF_TEXTURECOORDS;++c)
					{
						if (pMesh->HasTextureCoords( c))
						{
							pcMesh->mTextureCoords[c][pcMesh->mNumVertices] = pMesh->mTextureCoords[c][iIndex];
						}
					}
					// vertex colors 
					for (unsigned int c = 0;  c < AI_MAX_NUMBER_OF_COLOR_SETS;++c)
					{
						if (pMesh->HasVertexColors( c))
						{
							pcMesh->mColors[c][pcMesh->mNumVertices] = pMesh->mColors[c][iIndex];
						}
					}
					rFace.mIndices[v] = pcMesh->mNumVertices;
					avWasCopied[iIndex] = pcMesh->mNumVertices;
					pcMesh->mNumVertices++;
				}
				iBase++;
				if(pcMesh->mNumVertices == iOutVertexNum)
				{
					// break here. The face is only added if it was complete
					break;
				}
			}
			// copy the face list to the mesh
			pcMesh->mFaces = new aiFace[vFaces.size()];
			pcMesh->mNumFaces = vFaces.size();

			for (unsigned int p = 0; p < pcMesh->mNumFaces;++p)
				pcMesh->mFaces[p] = vFaces[p];

			// add the newly created mesh to the list
			avList.push_back(std::pair<aiMesh*, unsigned int>(pcMesh,a));

			if (iBase == pMesh->mNumFaces)
			{
				// have all faces ... finish the outer loop, too
				break;
			}
		}

		// now delete the old mesh data
		delete pMesh;
	}
	else avList.push_back(std::pair<aiMesh*, unsigned int>(pMesh,a));
	return;
}