320 lines
10 KiB
C++
320 lines
10 KiB
C++
/*
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Assimp2Json
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Copyright (c) 2011, Alexander C. Gessler
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Licensed under a 3-clause BSD license. See the LICENSE file for more information.
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*/
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#include "mesh_splitter.h"
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#include <assimp/scene.h>
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// ----------------------------------------------------------------------------
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// Note: this is largely based on assimp's SplitLargeMeshes_Vertex process.
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// it is refactored and the coding style is slightly improved, though.
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// ----------------------------------------------------------------------------
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// ------------------------------------------------------------------------------------------------
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// Executes the post processing step on the given imported data.
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void MeshSplitter::Execute( aiScene* pScene) {
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std::vector<std::pair<aiMesh*, unsigned int> > source_mesh_map;
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for( unsigned int a = 0; a < pScene->mNumMeshes; a++) {
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SplitMesh(a, pScene->mMeshes[a],source_mesh_map);
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}
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const unsigned int size = static_cast<unsigned int>(source_mesh_map.size());
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if (size != pScene->mNumMeshes) {
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// it seems something has been split. rebuild the mesh list
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delete[] pScene->mMeshes;
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pScene->mNumMeshes = size;
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pScene->mMeshes = new aiMesh*[size]();
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for (unsigned int i = 0; i < size;++i) {
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pScene->mMeshes[i] = source_mesh_map[i].first;
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}
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// now we need to update all nodes
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UpdateNode(pScene->mRootNode,source_mesh_map);
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}
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}
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// ------------------------------------------------------------------------------------------------
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void MeshSplitter::UpdateNode(aiNode* pcNode, const std::vector<std::pair<aiMesh*, unsigned int> >& source_mesh_map) {
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// TODO: should better use std::(multi)set for source_mesh_map.
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// for every index in out list build a new entry
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std::vector<unsigned int> aiEntries;
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aiEntries.reserve(pcNode->mNumMeshes + 1);
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for (unsigned int i = 0; i < pcNode->mNumMeshes;++i) {
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for (unsigned int a = 0, end = static_cast<unsigned int>(source_mesh_map.size()); a < end;++a) {
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if (source_mesh_map[a].second == pcNode->mMeshes[i]) {
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aiEntries.push_back(a);
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}
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}
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}
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// now build the new list
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delete pcNode->mMeshes;
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pcNode->mNumMeshes = static_cast<unsigned int>(aiEntries.size());
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pcNode->mMeshes = new unsigned int[pcNode->mNumMeshes];
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for (unsigned int b = 0; b < pcNode->mNumMeshes;++b) {
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pcNode->mMeshes[b] = aiEntries[b];
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}
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// recursively update children
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for (unsigned int i = 0, end = pcNode->mNumChildren; i < end;++i) {
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UpdateNode ( pcNode->mChildren[i], source_mesh_map );
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}
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}
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static const unsigned int WAS_NOT_COPIED = 0xffffffff;
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using PerVertexWeight = std::pair <unsigned int,float>;
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using VertexWeightTable = std::vector <PerVertexWeight>;
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// ------------------------------------------------------------------------------------------------
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VertexWeightTable* ComputeVertexBoneWeightTable(const aiMesh* pMesh) {
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if (!pMesh || !pMesh->mNumVertices || !pMesh->mNumBones) {
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return nullptr;
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}
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VertexWeightTable* const avPerVertexWeights = new VertexWeightTable[pMesh->mNumVertices];
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for (unsigned int i = 0; i < pMesh->mNumBones;++i) {
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aiBone* bone = pMesh->mBones[i];
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for (unsigned int a = 0; a < bone->mNumWeights;++a) {
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const aiVertexWeight& weight = bone->mWeights[a];
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avPerVertexWeights[weight.mVertexId].emplace_back(i,weight.mWeight);
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}
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}
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return avPerVertexWeights;
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}
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// ------------------------------------------------------------------------------------------------
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void MeshSplitter :: SplitMesh(unsigned int a, aiMesh* in_mesh, std::vector<std::pair<aiMesh*, unsigned int> >& source_mesh_map) {
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// TODO: should better use std::(multi)set for source_mesh_map.
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if (in_mesh->mNumVertices <= LIMIT) {
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source_mesh_map.emplace_back(in_mesh,a);
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return;
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}
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// build a per-vertex weight list if necessary
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VertexWeightTable* avPerVertexWeights = ComputeVertexBoneWeightTable(in_mesh);
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// we need to split this mesh into sub meshes. Estimate submesh size
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const unsigned int sub_meshes = (in_mesh->mNumVertices / LIMIT) + 1;
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// create a std::vector<unsigned int> to remember which vertices have already
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// been copied and to which position (i.e. output index)
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std::vector<unsigned int> was_copied_to;
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was_copied_to.resize(in_mesh->mNumVertices,WAS_NOT_COPIED);
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// Try to find a good estimate for the number of output faces
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// per mesh. Add 12.5% as buffer
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unsigned int size_estimated = in_mesh->mNumFaces / sub_meshes;
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size_estimated += size_estimated / 8;
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// now generate all submeshes
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unsigned int base = 0;
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while (true) {
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const unsigned int out_vertex_index = LIMIT;
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aiMesh* out_mesh = new aiMesh();
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out_mesh->mNumVertices = 0;
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out_mesh->mMaterialIndex = in_mesh->mMaterialIndex;
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// the name carries the adjacency information between the meshes
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out_mesh->mName = in_mesh->mName;
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typedef std::vector<aiVertexWeight> BoneWeightList;
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if (in_mesh->HasBones()) {
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out_mesh->mBones = new aiBone*[in_mesh->mNumBones]();
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}
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// clear the temporary helper array
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if (base) {
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std::fill(was_copied_to.begin(), was_copied_to.end(), WAS_NOT_COPIED);
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}
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std::vector<aiFace> vFaces;
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// reserve enough storage for most cases
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if (in_mesh->HasPositions()) {
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out_mesh->mVertices = new aiVector3D[out_vertex_index];
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}
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if (in_mesh->HasNormals()) {
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out_mesh->mNormals = new aiVector3D[out_vertex_index];
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}
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if (in_mesh->HasTangentsAndBitangents()) {
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out_mesh->mTangents = new aiVector3D[out_vertex_index];
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out_mesh->mBitangents = new aiVector3D[out_vertex_index];
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}
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for (unsigned int c = 0; in_mesh->HasVertexColors(c);++c) {
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out_mesh->mColors[c] = new aiColor4D[out_vertex_index];
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}
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for (unsigned int c = 0; in_mesh->HasTextureCoords(c);++c) {
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out_mesh->mNumUVComponents[c] = in_mesh->mNumUVComponents[c];
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out_mesh->mTextureCoords[c] = new aiVector3D[out_vertex_index];
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}
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vFaces.reserve(size_estimated);
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// (we will also need to copy the array of indices)
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while (base < in_mesh->mNumFaces) {
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const unsigned int iNumIndices = in_mesh->mFaces[base].mNumIndices;
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// doesn't catch degenerates but is quite fast
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unsigned int iNeed = 0;
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for (unsigned int v = 0; v < iNumIndices;++v) {
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unsigned int index = in_mesh->mFaces[base].mIndices[v];
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// check whether we do already have this vertex
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if (WAS_NOT_COPIED == was_copied_to[index]) {
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iNeed++;
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}
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}
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if (out_mesh->mNumVertices + iNeed > out_vertex_index) {
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// don't use this face
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break;
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}
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vFaces.emplace_back();
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aiFace& rFace = vFaces.back();
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// setup face type and number of indices
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rFace.mNumIndices = iNumIndices;
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rFace.mIndices = new unsigned int[iNumIndices];
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// need to update the output primitive types
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switch (rFace.mNumIndices)
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{
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case 1:
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out_mesh->mPrimitiveTypes |= aiPrimitiveType_POINT;
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break;
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case 2:
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out_mesh->mPrimitiveTypes |= aiPrimitiveType_LINE;
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break;
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case 3:
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out_mesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
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break;
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default:
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out_mesh->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
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}
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// and copy the contents of the old array, offset them by current base
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for (unsigned int v = 0; v < iNumIndices;++v) {
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const unsigned int index = in_mesh->mFaces[base].mIndices[v];
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// check whether we do already have this vertex
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if (WAS_NOT_COPIED != was_copied_to[index]) {
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rFace.mIndices[v] = was_copied_to[index];
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continue;
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}
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// copy positions
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out_mesh->mVertices[out_mesh->mNumVertices] = (in_mesh->mVertices[index]);
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// copy normals
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if (in_mesh->HasNormals()) {
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out_mesh->mNormals[out_mesh->mNumVertices] = (in_mesh->mNormals[index]);
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}
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// copy tangents/bi-tangents
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if (in_mesh->HasTangentsAndBitangents()) {
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out_mesh->mTangents[out_mesh->mNumVertices] = (in_mesh->mTangents[index]);
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out_mesh->mBitangents[out_mesh->mNumVertices] = (in_mesh->mBitangents[index]);
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}
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// texture coordinates
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for (unsigned int c = 0; c < AI_MAX_NUMBER_OF_TEXTURECOORDS;++c) {
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if (in_mesh->HasTextureCoords( c)) {
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out_mesh->mTextureCoords[c][out_mesh->mNumVertices] = in_mesh->mTextureCoords[c][index];
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}
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}
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// vertex colors
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for (unsigned int c = 0; c < AI_MAX_NUMBER_OF_COLOR_SETS;++c) {
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if (in_mesh->HasVertexColors( c)) {
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out_mesh->mColors[c][out_mesh->mNumVertices] = in_mesh->mColors[c][index];
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}
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}
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// check whether we have bone weights assigned to this vertex
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rFace.mIndices[v] = out_mesh->mNumVertices;
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if (avPerVertexWeights) {
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VertexWeightTable& table = avPerVertexWeights[ out_mesh->mNumVertices ];
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for (VertexWeightTable::const_iterator iter = table.begin(), end = table.end(); iter != end;++iter) {
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// allocate the bone weight array if necessary and store it in the mBones field (HACK!)
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BoneWeightList* weight_list = reinterpret_cast<BoneWeightList*>(out_mesh->mBones[(*iter).first]);
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if (!weight_list) {
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weight_list = new BoneWeightList();
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out_mesh->mBones[(*iter).first] = reinterpret_cast<aiBone*>(weight_list);
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}
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weight_list->push_back(aiVertexWeight(out_mesh->mNumVertices,(*iter).second));
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}
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}
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was_copied_to[index] = out_mesh->mNumVertices;
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out_mesh->mNumVertices++;
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}
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base++;
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if(out_mesh->mNumVertices == out_vertex_index) {
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// break here. The face is only added if it was complete
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break;
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}
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}
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// check which bones we'll need to create for this submesh
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if (in_mesh->HasBones()) {
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aiBone** ppCurrent = out_mesh->mBones;
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for (unsigned int k = 0; k < in_mesh->mNumBones;++k) {
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// check whether the bone exists
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BoneWeightList* const weight_list = reinterpret_cast<BoneWeightList*>(out_mesh->mBones[k]);
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if (weight_list) {
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const aiBone* const bone_in = in_mesh->mBones[k];
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aiBone* const bone_out = new aiBone();
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*ppCurrent++ = bone_out;
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bone_out->mName = aiString(bone_in->mName);
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bone_out->mOffsetMatrix =bone_in->mOffsetMatrix;
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bone_out->mNumWeights = (unsigned int)weight_list->size();
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bone_out->mWeights = new aiVertexWeight[bone_out->mNumWeights];
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// copy the vertex weights
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::memcpy(bone_out->mWeights, &(*weight_list)[0],bone_out->mNumWeights * sizeof(aiVertexWeight));
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delete weight_list;
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out_mesh->mNumBones++;
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}
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}
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}
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// copy the face list to the mesh
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out_mesh->mFaces = new aiFace[vFaces.size()];
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out_mesh->mNumFaces = (unsigned int)vFaces.size();
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for (unsigned int p = 0; p < out_mesh->mNumFaces;++p) {
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out_mesh->mFaces[p] = vFaces[p];
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}
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// add the newly created mesh to the list
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source_mesh_map.emplace_back(out_mesh,a);
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if (base == in_mesh->mNumFaces) {
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break;
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}
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}
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// delete the per-vertex weight list again
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delete[] avPerVertexWeights;
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// now delete the old mesh data
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delete in_mesh;
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}
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