assimp/code/PretransformVertices.cpp

/*
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/** @file PretransformVertices.cpp
 *  @brief Implementation of the "PretransformVertices" post processing step
*/


#include "PretransformVertices.h"
#include "ProcessHelper.h"
#include "SceneCombiner.h"
#include "Exceptional.h"

using namespace Assimp;

// some array offsets
#define AI_PTVS_VERTEX 0x0
#define AI_PTVS_FACE 0x1

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
PretransformVertices::PretransformVertices()
:   configKeepHierarchy (false), configNormalize(false), configTransform(false), configTransformation()
{
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
PretransformVertices::~PretransformVertices()
{
    // nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool PretransformVertices::IsActive( unsigned int pFlags) const
{
    return  (pFlags & aiProcess_PreTransformVertices) != 0;
}

// ------------------------------------------------------------------------------------------------
// Setup import configuration
void PretransformVertices::SetupProperties(const Importer* pImp)
{
    // Get the current value of AI_CONFIG_PP_PTV_KEEP_HIERARCHY, AI_CONFIG_PP_PTV_NORMALIZE,
    // AI_CONFIG_PP_PTV_ADD_ROOT_TRANSFORMATION and AI_CONFIG_PP_PTV_ROOT_TRANSFORMATION
    configKeepHierarchy = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_KEEP_HIERARCHY,0));
    configNormalize = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_NORMALIZE,0));
    configTransform = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_ADD_ROOT_TRANSFORMATION,0));

    configTransformation = pImp->GetPropertyMatrix(AI_CONFIG_PP_PTV_ROOT_TRANSFORMATION, aiMatrix4x4());
}

// ------------------------------------------------------------------------------------------------
// Count the number of nodes
unsigned int PretransformVertices::CountNodes( aiNode* pcNode )
{
    unsigned int iRet = 1;
    for (unsigned int i = 0;i < pcNode->mNumChildren;++i)
    {
        iRet += CountNodes(pcNode->mChildren[i]);
    }
    return iRet;
}

// ------------------------------------------------------------------------------------------------
// Get a bitwise combination identifying the vertex format of a mesh
unsigned int PretransformVertices::GetMeshVFormat(aiMesh* pcMesh)
{
    // the vertex format is stored in aiMesh::mBones for later retrieval.
    // there isn't a good reason to compute it a few hundred times
    // from scratch. The pointer is unused as animations are lost
    // during PretransformVertices.
    if (pcMesh->mBones)
        return (unsigned int)(uint64_t)pcMesh->mBones;


    const unsigned int iRet = GetMeshVFormatUnique(pcMesh);

    // store the value for later use
    pcMesh->mBones = (aiBone**)(uint64_t)iRet;
    return iRet;
}

// ------------------------------------------------------------------------------------------------
// Count the number of vertices in the whole scene and a given
// material index
void PretransformVertices::CountVerticesAndFaces( aiScene* pcScene, aiNode* pcNode, unsigned int iMat,
    unsigned int iVFormat, unsigned int* piFaces, unsigned int* piVertices)
{
    for (unsigned int i = 0; i < pcNode->mNumMeshes;++i)
    {
        aiMesh* pcMesh = pcScene->mMeshes[ pcNode->mMeshes[i] ];
        if (iMat == pcMesh->mMaterialIndex && iVFormat == GetMeshVFormat(pcMesh))
        {
            *piVertices += pcMesh->mNumVertices;
            *piFaces += pcMesh->mNumFaces;
        }
    }
    for (unsigned int i = 0;i < pcNode->mNumChildren;++i)
    {
        CountVerticesAndFaces(pcScene,pcNode->mChildren[i],iMat,
            iVFormat,piFaces,piVertices);
    }
}

// ------------------------------------------------------------------------------------------------
// Collect vertex/face data
void PretransformVertices::CollectData( aiScene* pcScene, aiNode* pcNode, unsigned int iMat,
    unsigned int iVFormat, aiMesh* pcMeshOut,
    unsigned int aiCurrent[2], unsigned int* num_refs)
{
    // No need to multiply if there's no transformation
    const bool identity = pcNode->mTransformation.IsIdentity();
    for (unsigned int i = 0; i < pcNode->mNumMeshes;++i)
    {
        aiMesh* pcMesh = pcScene->mMeshes[ pcNode->mMeshes[i] ];
        if (iMat == pcMesh->mMaterialIndex && iVFormat == GetMeshVFormat(pcMesh))
        {
            // Decrement mesh reference counter
            unsigned int& num_ref = num_refs[pcNode->mMeshes[i]];
            ai_assert(0 != num_ref);
            --num_ref;

            if (identity)   {
                // copy positions without modifying them
                ::memcpy(pcMeshOut->mVertices + aiCurrent[AI_PTVS_VERTEX],
                    pcMesh->mVertices,
                    pcMesh->mNumVertices * sizeof(aiVector3D));

                if (iVFormat & 0x2) {
                    // copy normals without modifying them
                    ::memcpy(pcMeshOut->mNormals + aiCurrent[AI_PTVS_VERTEX],
                        pcMesh->mNormals,
                        pcMesh->mNumVertices * sizeof(aiVector3D));
                }
                if (iVFormat & 0x4)
                {
                    // copy tangents without modifying them
                    ::memcpy(pcMeshOut->mTangents + aiCurrent[AI_PTVS_VERTEX],
                        pcMesh->mTangents,
                        pcMesh->mNumVertices * sizeof(aiVector3D));
                    // copy bitangents without modifying them
                    ::memcpy(pcMeshOut->mBitangents + aiCurrent[AI_PTVS_VERTEX],
                        pcMesh->mBitangents,
                        pcMesh->mNumVertices * sizeof(aiVector3D));
                }
            }
            else
            {
                // copy positions, transform them to worldspace
                for (unsigned int n = 0; n < pcMesh->mNumVertices;++n)  {
                    pcMeshOut->mVertices[aiCurrent[AI_PTVS_VERTEX]+n] = pcNode->mTransformation * pcMesh->mVertices[n];
                }
                aiMatrix4x4 mWorldIT = pcNode->mTransformation;
                mWorldIT.Inverse().Transpose();

                // TODO: implement Inverse() for aiMatrix3x3
                aiMatrix3x3 m = aiMatrix3x3(mWorldIT);

                if (iVFormat & 0x2)
                {
                    // copy normals, transform them to worldspace
                    for (unsigned int n = 0; n < pcMesh->mNumVertices;++n)  {
                        pcMeshOut->mNormals[aiCurrent[AI_PTVS_VERTEX]+n] =
                            (m * pcMesh->mNormals[n]).Normalize();
                    }
                }
                if (iVFormat & 0x4)
                {
                    // copy tangents and bitangents, transform them to worldspace
                    for (unsigned int n = 0; n < pcMesh->mNumVertices;++n)  {
                        pcMeshOut->mTangents  [aiCurrent[AI_PTVS_VERTEX]+n] = (m * pcMesh->mTangents[n]).Normalize();
                        pcMeshOut->mBitangents[aiCurrent[AI_PTVS_VERTEX]+n] = (m * pcMesh->mBitangents[n]).Normalize();
                    }
                }
            }
            unsigned int p = 0;
            while (iVFormat & (0x100 << p))
            {
                // copy texture coordinates
                memcpy(pcMeshOut->mTextureCoords[p] + aiCurrent[AI_PTVS_VERTEX],
                    pcMesh->mTextureCoords[p],
                    pcMesh->mNumVertices * sizeof(aiVector3D));
                ++p;
            }
            p = 0;
            while (iVFormat & (0x1000000 << p))
            {
                // copy vertex colors
                memcpy(pcMeshOut->mColors[p] + aiCurrent[AI_PTVS_VERTEX],
                    pcMesh->mColors[p],
                    pcMesh->mNumVertices * sizeof(aiColor4D));
                ++p;
            }
            // now we need to copy all faces. since we will delete the source mesh afterwards,
            // we don't need to reallocate the array of indices except if this mesh is
            // referenced multiple times.
            for (unsigned int planck = 0;planck < pcMesh->mNumFaces;++planck)
            {
                aiFace& f_src = pcMesh->mFaces[planck];
                aiFace& f_dst = pcMeshOut->mFaces[aiCurrent[AI_PTVS_FACE]+planck];

                const unsigned int num_idx = f_src.mNumIndices;

                f_dst.mNumIndices = num_idx;

                unsigned int* pi;
                if (!num_ref) { /* if last time the mesh is referenced -> no reallocation */
                    pi = f_dst.mIndices = f_src.mIndices;

                    // offset all vertex indices
                    for (unsigned int hahn = 0; hahn < num_idx;++hahn){
                        pi[hahn] += aiCurrent[AI_PTVS_VERTEX];
                    }
                }
                else {
                    pi = f_dst.mIndices = new unsigned int[num_idx];

                    // copy and offset all vertex indices
                    for (unsigned int hahn = 0; hahn < num_idx;++hahn){
                        pi[hahn] = f_src.mIndices[hahn] + aiCurrent[AI_PTVS_VERTEX];
                    }
                }

                // Update the mPrimitiveTypes member of the mesh
                switch (pcMesh->mFaces[planck].mNumIndices)
                {
                case 0x1:
                    pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_POINT;
                    break;
                case 0x2:
                    pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_LINE;
                    break;
                case 0x3:
                    pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
                    break;
                default:
                    pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
                    break;
                };
            }
            aiCurrent[AI_PTVS_VERTEX] += pcMesh->mNumVertices;
            aiCurrent[AI_PTVS_FACE]   += pcMesh->mNumFaces;
        }
    }

    // append all children of us
    for (unsigned int i = 0;i < pcNode->mNumChildren;++i) {
        CollectData(pcScene,pcNode->mChildren[i],iMat,
            iVFormat,pcMeshOut,aiCurrent,num_refs);
    }
}

// ------------------------------------------------------------------------------------------------
// Get a list of all vertex formats that occur for a given material index
// The output list contains duplicate elements
void PretransformVertices::GetVFormatList( aiScene* pcScene, unsigned int iMat,
    std::list<unsigned int>& aiOut)
{
    for (unsigned int i = 0; i < pcScene->mNumMeshes;++i)
    {
        aiMesh* pcMesh = pcScene->mMeshes[ i ];
        if (iMat == pcMesh->mMaterialIndex) {
            aiOut.push_back(GetMeshVFormat(pcMesh));
        }
    }
}

// ------------------------------------------------------------------------------------------------
// Compute the absolute transformation matrices of each node
void PretransformVertices::ComputeAbsoluteTransform( aiNode* pcNode )
{
    if (pcNode->mParent)    {
        pcNode->mTransformation = pcNode->mParent->mTransformation*pcNode->mTransformation;
    }

    for (unsigned int i = 0;i < pcNode->mNumChildren;++i)   {
        ComputeAbsoluteTransform(pcNode->mChildren[i]);
    }
}

// ------------------------------------------------------------------------------------------------
// Apply the node transformation to a mesh
void PretransformVertices::ApplyTransform(aiMesh* mesh, const aiMatrix4x4& mat)
{
    // Check whether we need to transform the coordinates at all
    if (!mat.IsIdentity()) {

        if (mesh->HasPositions()) {
            for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
                mesh->mVertices[i] = mat * mesh->mVertices[i];
            }
        }
        if (mesh->HasNormals() || mesh->HasTangentsAndBitangents()) {
            aiMatrix4x4 mWorldIT = mat;
            mWorldIT.Inverse().Transpose();

            // TODO: implement Inverse() for aiMatrix3x3
            aiMatrix3x3 m = aiMatrix3x3(mWorldIT);

            if (mesh->HasNormals()) {
                for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
                    mesh->mNormals[i] = (m * mesh->mNormals[i]).Normalize();
                }
            }
            if (mesh->HasTangentsAndBitangents()) {
                for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
                    mesh->mTangents[i]   = (m * mesh->mTangents[i]).Normalize();
                    mesh->mBitangents[i] = (m * mesh->mBitangents[i]).Normalize();
                }
            }
        }
    }
}

// ------------------------------------------------------------------------------------------------
// Simple routine to build meshes in worldspace, no further optimization
void PretransformVertices::BuildWCSMeshes(std::vector<aiMesh*>& out, aiMesh** in,
    unsigned int numIn, aiNode* node)
{
    // NOTE:
    //  aiMesh::mNumBones store original source mesh, or UINT_MAX if not a copy
    //  aiMesh::mBones store reference to abs. transform we multiplied with

    // process meshes
    for (unsigned int i = 0; i < node->mNumMeshes;++i) {
        aiMesh* mesh = in[node->mMeshes[i]];

        // check whether we can operate on this mesh
        if (!mesh->mBones || *reinterpret_cast<aiMatrix4x4*>(mesh->mBones) == node->mTransformation) {
            // yes, we can.
            mesh->mBones = reinterpret_cast<aiBone**> (&node->mTransformation);
            mesh->mNumBones = UINT_MAX;
        }
        else {

            // try to find us in the list of newly created meshes
            for (unsigned int n = 0; n < out.size(); ++n) {
                aiMesh* ctz = out[n];
                if (ctz->mNumBones == node->mMeshes[i] && *reinterpret_cast<aiMatrix4x4*>(ctz->mBones) ==  node->mTransformation) {

                    // ok, use this one. Update node mesh index
                    node->mMeshes[i] = numIn + n;
                }
            }
            if (node->mMeshes[i] < numIn) {
                // Worst case. Need to operate on a full copy of the mesh
                DefaultLogger::get()->info("PretransformVertices: Copying mesh due to mismatching transforms");
                aiMesh* ntz;

                const unsigned int tmp = mesh->mNumBones; //
                mesh->mNumBones = 0;
                SceneCombiner::Copy(&ntz,mesh);
                mesh->mNumBones = tmp;

                ntz->mNumBones = node->mMeshes[i];
                ntz->mBones = reinterpret_cast<aiBone**> (&node->mTransformation);

                out.push_back(ntz);

                node->mMeshes[i] = numIn + out.size() - 1;
            }
        }
    }

    // call children
    for (unsigned int i = 0; i < node->mNumChildren;++i)
        BuildWCSMeshes(out,in,numIn,node->mChildren[i]);
}

// ------------------------------------------------------------------------------------------------
// Reset transformation matrices to identity
void PretransformVertices::MakeIdentityTransform(aiNode* nd)
{
    nd->mTransformation = aiMatrix4x4();

    // call children
    for (unsigned int i = 0; i < nd->mNumChildren;++i)
        MakeIdentityTransform(nd->mChildren[i]);
}

// ------------------------------------------------------------------------------------------------
// Build reference counters for all meshes
void PretransformVertices::BuildMeshRefCountArray(aiNode* nd, unsigned int * refs)
{
    for (unsigned int i = 0; i< nd->mNumMeshes;++i)
        refs[nd->mMeshes[i]]++;

    // call children
    for (unsigned int i = 0; i < nd->mNumChildren;++i)
        BuildMeshRefCountArray(nd->mChildren[i],refs);
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void PretransformVertices::Execute( aiScene* pScene)
{
    DefaultLogger::get()->debug("PretransformVerticesProcess begin");

    // Return immediately if we have no meshes
    if (!pScene->mNumMeshes)
        return;

    const unsigned int iOldMeshes = pScene->mNumMeshes;
    const unsigned int iOldAnimationChannels = pScene->mNumAnimations;
    const unsigned int iOldNodes = CountNodes(pScene->mRootNode);

    if(configTransform) {
        pScene->mRootNode->mTransformation = configTransformation;
    }

    // first compute absolute transformation matrices for all nodes
    ComputeAbsoluteTransform(pScene->mRootNode);

    // Delete aiMesh::mBones for all meshes. The bones are
    // removed during this step and we need the pointer as
    // temporary storage
    for (unsigned int i = 0; i < pScene->mNumMeshes;++i)    {
        aiMesh* mesh = pScene->mMeshes[i];

        for (unsigned int a = 0; a < mesh->mNumBones;++a)
            delete mesh->mBones[a];

        delete[] mesh->mBones;
        mesh->mBones = NULL;
    }

    // now build a list of output meshes
    std::vector<aiMesh*> apcOutMeshes;

    // Keep scene hierarchy? It's an easy job in this case ...
    // we go on and transform all meshes, if one is referenced by nodes
    // with different absolute transformations a depth copy of the mesh
    // is required.
    if( configKeepHierarchy ) {

        // Hack: store the matrix we're transforming a mesh with in aiMesh::mBones
        BuildWCSMeshes(apcOutMeshes,pScene->mMeshes,pScene->mNumMeshes, pScene->mRootNode);

        // ... if new meshes have been generated, append them to the end of the scene
        if (apcOutMeshes.size() > 0) {
            aiMesh** npp = new aiMesh*[pScene->mNumMeshes + apcOutMeshes.size()];

            memcpy(npp,pScene->mMeshes,sizeof(aiMesh*)*pScene->mNumMeshes);
            memcpy(npp+pScene->mNumMeshes,&apcOutMeshes[0],sizeof(aiMesh*)*apcOutMeshes.size());

            pScene->mNumMeshes  += apcOutMeshes.size();
            delete[] pScene->mMeshes; pScene->mMeshes = npp;
        }

        // now iterate through all meshes and transform them to worldspace
        for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
            ApplyTransform(pScene->mMeshes[i],*reinterpret_cast<aiMatrix4x4*>( pScene->mMeshes[i]->mBones ));

            // prevent improper destruction
            pScene->mMeshes[i]->mBones    = NULL;
            pScene->mMeshes[i]->mNumBones = 0;
        }
    }
    else {

        apcOutMeshes.reserve(pScene->mNumMaterials<<1u);
        std::list<unsigned int> aiVFormats;

        std::vector<unsigned int> s(pScene->mNumMeshes,0);
        BuildMeshRefCountArray(pScene->mRootNode,&s[0]);

        for (unsigned int i = 0; i < pScene->mNumMaterials;++i)     {
            // get the list of all vertex formats for this material
            aiVFormats.clear();
            GetVFormatList(pScene,i,aiVFormats);
            aiVFormats.sort();
            aiVFormats.unique();
            for (std::list<unsigned int>::const_iterator j =  aiVFormats.begin();j != aiVFormats.end();++j) {
                unsigned int iVertices = 0;
                unsigned int iFaces = 0;
                CountVerticesAndFaces(pScene,pScene->mRootNode,i,*j,&iFaces,&iVertices);
                if (0 != iFaces && 0 != iVertices)
                {
                    apcOutMeshes.push_back(new aiMesh());
                    aiMesh* pcMesh = apcOutMeshes.back();
                    pcMesh->mNumFaces = iFaces;
                    pcMesh->mNumVertices = iVertices;
                    pcMesh->mFaces = new aiFace[iFaces];
                    pcMesh->mVertices = new aiVector3D[iVertices];
                    pcMesh->mMaterialIndex = i;
                    if ((*j) & 0x2)pcMesh->mNormals = new aiVector3D[iVertices];
                    if ((*j) & 0x4)
                    {
                        pcMesh->mTangents    = new aiVector3D[iVertices];
                        pcMesh->mBitangents  = new aiVector3D[iVertices];
                    }
                    iFaces = 0;
                    while ((*j) & (0x100 << iFaces))
                    {
                        pcMesh->mTextureCoords[iFaces] = new aiVector3D[iVertices];
                        if ((*j) & (0x10000 << iFaces))pcMesh->mNumUVComponents[iFaces] = 3;
                        else pcMesh->mNumUVComponents[iFaces] = 2;
                        iFaces++;
                    }
                    iFaces = 0;
                    while ((*j) & (0x1000000 << iFaces))
                        pcMesh->mColors[iFaces++] = new aiColor4D[iVertices];

                    // fill the mesh ...
                    unsigned int aiTemp[2] = {0,0};
                    CollectData(pScene,pScene->mRootNode,i,*j,pcMesh,aiTemp,&s[0]);
                }
            }
        }

        // If no meshes are referenced in the node graph it is possible that we get no output meshes.
        if (apcOutMeshes.empty())   {
            throw DeadlyImportError("No output meshes: all meshes are orphaned and are not referenced by any nodes");
        }
        else
        {
            // now delete all meshes in the scene and build a new mesh list
            for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
            {
                aiMesh* mesh = pScene->mMeshes[i];
                mesh->mNumBones = 0;
                mesh->mBones    = NULL;

                // we're reusing the face index arrays. avoid destruction
                for (unsigned int a = 0; a < mesh->mNumFaces; ++a) {
                    mesh->mFaces[a].mNumIndices = 0;
                    mesh->mFaces[a].mIndices = NULL;
                }

                delete mesh;

                // Invalidate the contents of the old mesh array. We will most
                // likely have less output meshes now, so the last entries of
                // the mesh array are not overridden. We set them to NULL to
                // make sure the developer gets notified when his application
                // attempts to access these fields ...
                mesh = NULL;
            }

            // It is impossible that we have more output meshes than
            // input meshes, so we can easily reuse the old mesh array
            pScene->mNumMeshes = (unsigned int)apcOutMeshes.size();
            for (unsigned int i = 0; i < pScene->mNumMeshes;++i) {
                pScene->mMeshes[i] = apcOutMeshes[i];
            }
        }
    }

    // remove all animations from the scene
    for (unsigned int i = 0; i < pScene->mNumAnimations;++i)
        delete pScene->mAnimations[i];
    delete[] pScene->mAnimations;

    pScene->mAnimations    = NULL;
    pScene->mNumAnimations = 0;

    // --- we need to keep all cameras and lights
    for (unsigned int i = 0; i < pScene->mNumCameras;++i)
    {
        aiCamera* cam = pScene->mCameras[i];
        const aiNode* nd = pScene->mRootNode->FindNode(cam->mName);
        ai_assert(NULL != nd);

        // multiply all properties of the camera with the absolute
        // transformation of the corresponding node
        cam->mPosition = nd->mTransformation * cam->mPosition;
        cam->mLookAt   = aiMatrix3x3( nd->mTransformation ) * cam->mLookAt;
        cam->mUp       = aiMatrix3x3( nd->mTransformation ) * cam->mUp;
    }

    for (unsigned int i = 0; i < pScene->mNumLights;++i)
    {
        aiLight* l = pScene->mLights[i];
        const aiNode* nd = pScene->mRootNode->FindNode(l->mName);
        ai_assert(NULL != nd);

        // multiply all properties of the camera with the absolute
        // transformation of the corresponding node
        l->mPosition   = nd->mTransformation * l->mPosition;
        l->mDirection  = aiMatrix3x3( nd->mTransformation ) * l->mDirection;
        l->mUp         = aiMatrix3x3( nd->mTransformation ) * l->mUp;
    }

    if( !configKeepHierarchy ) {

        // now delete all nodes in the scene and build a new
        // flat node graph with a root node and some level 1 children
        delete pScene->mRootNode;
        pScene->mRootNode = new aiNode();
        pScene->mRootNode->mName.Set("<dummy_root>");

        if (1 == pScene->mNumMeshes && !pScene->mNumLights && !pScene->mNumCameras)
        {
            pScene->mRootNode->mNumMeshes = 1;
            pScene->mRootNode->mMeshes = new unsigned int[1];
            pScene->mRootNode->mMeshes[0] = 0;
        }
        else
        {
            pScene->mRootNode->mNumChildren = pScene->mNumMeshes+pScene->mNumLights+pScene->mNumCameras;
            aiNode** nodes = pScene->mRootNode->mChildren = new aiNode*[pScene->mRootNode->mNumChildren];

            // generate mesh nodes
            for (unsigned int i = 0; i < pScene->mNumMeshes;++i,++nodes)
            {
                aiNode* pcNode = *nodes = new aiNode();
                pcNode->mParent = pScene->mRootNode;
                pcNode->mName.length = ::ai_snprintf(pcNode->mName.data,MAXLEN,"mesh_%u",i);

                // setup mesh indices
                pcNode->mNumMeshes = 1;
                pcNode->mMeshes = new unsigned int[1];
                pcNode->mMeshes[0] = i;
            }
            // generate light nodes
            for (unsigned int i = 0; i < pScene->mNumLights;++i,++nodes)
            {
                aiNode* pcNode = *nodes = new aiNode();
                pcNode->mParent = pScene->mRootNode;
                pcNode->mName.length = ai_snprintf(pcNode->mName.data, MAXLEN, "light_%u",i);
                pScene->mLights[i]->mName = pcNode->mName;
            }
            // generate camera nodes
            for (unsigned int i = 0; i < pScene->mNumCameras;++i,++nodes)
            {
                aiNode* pcNode = *nodes = new aiNode();
                pcNode->mParent = pScene->mRootNode;
                pcNode->mName.length = ::ai_snprintf(pcNode->mName.data,MAXLEN,"cam_%u",i);
                pScene->mCameras[i]->mName = pcNode->mName;
            }
        }
    }
    else {
        // ... and finally set the transformation matrix of all nodes to identity
        MakeIdentityTransform(pScene->mRootNode);
    }

    if (configNormalize) {
        // compute the boundary of all meshes
        aiVector3D min,max;
        MinMaxChooser<aiVector3D> ()(min,max);

        for (unsigned int a = 0; a <  pScene->mNumMeshes; ++a) {
            aiMesh* m = pScene->mMeshes[a];
            for (unsigned int i = 0; i < m->mNumVertices;++i) {
                min = std::min(m->mVertices[i],min);
                max = std::max(m->mVertices[i],max);
            }
        }

        // find the dominant axis
        aiVector3D d = max-min;
        const float div = std::max(d.x,std::max(d.y,d.z))*0.5f;

        d = min+d*0.5f;
        for (unsigned int a = 0; a <  pScene->mNumMeshes; ++a) {
            aiMesh* m = pScene->mMeshes[a];
            for (unsigned int i = 0; i < m->mNumVertices;++i) {
                m->mVertices[i] = (m->mVertices[i]-d)/div;
            }
        }
    }

    // print statistics
    if (!DefaultLogger::isNullLogger())
    {
        char buffer[4096];

        DefaultLogger::get()->debug("PretransformVerticesProcess finished");

        ::ai_snprintf(buffer,4096,"Removed %u nodes and %u animation channels (%u output nodes)",
            iOldNodes,iOldAnimationChannels,CountNodes(pScene->mRootNode));
        DefaultLogger::get()->info(buffer);

        ai_snprintf(buffer, 4096,"Kept %u lights and %u cameras",
            pScene->mNumLights,pScene->mNumCameras);
        DefaultLogger::get()->info(buffer);

        ai_snprintf(buffer, 4096,"Moved %u meshes to WCS (number of output meshes: %u)",
            iOldMeshes,pScene->mNumMeshes);
        DefaultLogger::get()->info(buffer);
    }
}