assimp/code/Assjson/mesh_splitter.cpp

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