assimp/code/SplitLargeMeshes.cpp

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

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*/


/** @file Implementation of the SplitLargeMeshes postprocessing step
*/
#include "SplitLargeMeshes.h"
#include "DefaultLogger.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;
	DefaultLogger::get()->debug("aiSetVertexSplitLimit() - vertex split limit was changed");
	return AI_SUCCESS;
}
// ------------------------------------------------------------------------------------------------
aiReturn aiSetTriangleSplitLimit(unsigned int pLimit)
{
	if (0 == pLimit)
	{
		SplitLargeMeshesProcess_Triangle::LIMIT = 0xFFFFFFFF;
		return AI_FAILURE;
	}

	SplitLargeMeshesProcess_Triangle::LIMIT = pLimit;
	DefaultLogger::get()->debug("aiSetTriangleSplitLimit() - triangle split limit was changed");
	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)
{
	DefaultLogger::get()->debug("SplitLargeMeshesProcess_Triangle begin");
	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);
		DefaultLogger::get()->info("SplitLargeMeshesProcess_Triangle finished. Meshes have been splitted");
	}
	else DefaultLogger::get()->debug("SplitLargeMeshesProcess_Triangle finished. There was nothing to do");
	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 > SplitLargeMeshesProcess_Triangle::LIMIT)
	{
		DefaultLogger::get()->info("Mesh exceeds the triangle limit. It will be split ...");

		// 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;

	DefaultLogger::get()->debug("SplitLargeMeshesProcess_Vertex begin");
	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);
		DefaultLogger::get()->info("SplitLargeMeshesProcess_Vertex finished. Meshes have been splitted");
	}
	else DefaultLogger::get()->debug("SplitLargeMeshesProcess_Vertex finished. There was nothing to do");
	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;
		return;
	}
	avList.push_back(std::pair<aiMesh*, unsigned int>(pMesh,a));
	return;
}