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/// @file  PretransformVertices.cpp

/// @brief Implementation of the "PretransformVertices" post processing step

#include "PretransformVertices.h"

#include "ConvertToLHProcess.h"

#include "ProcessHelper.h"

#include <assimp/Exceptional.h>

#include <assimp/SceneCombiner.h>

using namespace Assimp;

// some array offsets

#define AI_PTVS_VERTEX 0x0

#define AI_PTVS_FACE 0x1

namespace {

// Get a bitwise combination identifying the vertex format of a mesh

static unsigned int 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;

}

// Get a list of all vertex formats that occur for a given material index

// The output list contains duplicate elements

static void GetVFormatList(const 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));

    }

  }

}

}

// ------------------------------------------------------------------------------------------------

// Constructor to be privately used by Importer

PretransformVertices::PretransformVertices() :

    mConfigKeepHierarchy(false),

    mConfigNormalize(false),

    mConfigTransform(false),

    mConfigTransformation(),

    mConfigPointCloud(false) {}

// ------------------------------------------------------------------------------------------------

// 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

  mConfigKeepHierarchy = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_KEEP_HIERARCHY, 0));

  mConfigNormalize = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_NORMALIZE, 0));

  mConfigTransform = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_ADD_ROOT_TRANSFORMATION, 0));

  mConfigTransformation = pImp->GetPropertyMatrix(AI_CONFIG_PP_PTV_ROOT_TRANSFORMATION, aiMatrix4x4());

  mConfigPointCloud = pImp->GetPropertyBool(AI_CONFIG_EXPORT_POINT_CLOUDS);

}

// ------------------------------------------------------------------------------------------------

// Count the number of nodes

unsigned int PretransformVertices::CountNodes(const aiNode *pcNode) const {

  unsigned int iRet = 1;

  for (unsigned int i = 0; i < pcNode->mNumChildren; ++i) {

    iRet += CountNodes(pcNode->mChildren[i]);

  }

  return iRet;

}

// ------------------------------------------------------------------------------------------------

// Count the number of vertices in the whole scene and a given material index

void PretransformVertices::CountVerticesAndFaces(const aiScene *pcScene, const aiNode *pcNode, unsigned int iMat,

    unsigned int iVFormat, unsigned int *piFaces, unsigned int *piVertices) const {

  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(const aiScene *pcScene, const aiNode *pcNode, unsigned int iMat,

    unsigned int iVFormat, aiMesh *pcMeshOut,

    unsigned int aiCurrent[2], unsigned int *num_refs) const {

  // 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;

      // Save the name of the last mesh

      if (num_ref == 0) {

        pcMeshOut->mName = pcMesh->mName;

      }

      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);

  }

}

// ------------------------------------------------------------------------------------------------

// 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) const {

  // Check whether we need to transform the coordinates at all

  if (mat.IsIdentity()) {

    return;

  }

  // Check for odd negative scale (mirror)

  if (mesh->HasFaces() && mat.Determinant() < 0) {

    // Reverse the mesh face winding order

    FlipWindingOrderProcess::ProcessMesh(mesh);

  }

  // Update positions

  if (mesh->HasPositions()) {

    for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {

      mesh->mVertices[i] = mat * mesh->mVertices[i];

    }

  }

  // Update normals and tangents

  if (mesh->HasNormals() || mesh->HasTangentsAndBitangents()) {

    const aiMatrix3x3 m = aiMatrix3x3(mat).Inverse().Transpose();

    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) const {

  // 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;

      continue;

    }

    // 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

      ASSIMP_LOG_INFO("PretransformVertices: Copying mesh due to mismatching transforms");

      aiMesh *ntz;

      const unsigned int cacheNumBones = mesh->mNumBones; //

      mesh->mNumBones = 0;

      SceneCombiner::Copy(&ntz, mesh);

      mesh->mNumBones = cacheNumBones;

      ntz->mNumBones = node->mMeshes[i];

      ntz->mBones = reinterpret_cast<aiBone **>(&node->mTransformation);

      out.push_back(ntz);

      node->mMeshes[i] = static_cast<unsigned int>(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) const {

  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(const aiNode *nd, unsigned int *refs) const {

  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);

  }

}

// ------------------------------------------------------------------------------------------------

static void appendNewMeshesToScene(aiScene *pScene, std::vector<aiMesh*> &apcOutMeshes) {

  ai_assert(pScene != nullptr);

  if (apcOutMeshes.empty()) {

    return;

  }

  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 += static_cast<unsigned int>(apcOutMeshes.size());

  delete[] pScene->mMeshes;

  pScene->mMeshes = npp;

}

// ------------------------------------------------------------------------------------------------

// Executes the post processing step on the given imported data.

void PretransformVertices::Execute(aiScene *pScene) {

  ASSIMP_LOG_DEBUG("PretransformVerticesProcess begin");

  // Return immediately if we have no meshes

  if (!pScene->mNumMeshes)

    return;

  const unsigned int oldMeshes = pScene->mNumMeshes;

  const unsigned int oldAnimationChannels = pScene->mNumAnimations;

  const unsigned int oldNodes = CountNodes(pScene->mRootNode);

  if (mConfigTransform) {

    pScene->mRootNode->mTransformation = mConfigTransformation * pScene->mRootNode->mTransformation;

  }

  // 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 = nullptr;

  }

  // 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 (mConfigKeepHierarchy) {

    // 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

    appendNewMeshesToScene(pScene, apcOutMeshes);

    // now iterate through all meshes and transform them to world-space

    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 = nullptr;

      pScene->mMeshes[i]->mNumBones = 0;

    }

  } else {

    apcOutMeshes.reserve(static_cast<size_t>(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 numVertices = 0u;

        unsigned int numFaces = 0u;

        CountVerticesAndFaces(pScene, pScene->mRootNode, i, *j, &numFaces, &numVertices);

        if (0 != numFaces && 0 != numVertices) {

          apcOutMeshes.push_back(new aiMesh());

          aiMesh *pcMesh = apcOutMeshes.back();

          pcMesh->mNumFaces = numFaces;

          pcMesh->mNumVertices = numVertices;

          pcMesh->mFaces = new aiFace[numFaces];

          pcMesh->mVertices = new aiVector3D[numVertices];

          pcMesh->mMaterialIndex = i;

          if ((*j) & 0x2) pcMesh->mNormals = new aiVector3D[numVertices];

          if ((*j) & 0x4) {

            pcMesh->mTangents = new aiVector3D[numVertices];

            pcMesh->mBitangents = new aiVector3D[numVertices];

          }

          numFaces = 0;

          while ((*j) & (0x100 << numFaces)) {

            pcMesh->mTextureCoords[numFaces] = new aiVector3D[numVertices];

            if ((*j) & (0x10000 << numFaces)) {

              pcMesh->mNumUVComponents[numFaces] = 3;

            } else {

              pcMesh->mNumUVComponents[numFaces] = 2;

            }

            ++numFaces;

          }

          numFaces = 0;

          while ((*j) & (0x1000000 << numFaces))

            pcMesh->mColors[numFaces++] = new aiColor4D[numVertices];

          // 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 = nullptr;

        // 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 = nullptr;

        }

        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 nullptr to

        // make sure the developer gets notified when his application

        // attempts to access these fields ...

                mesh = nullptr;

      }

      // 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 = nullptr;

  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(nullptr != nd);

    // multiply all properties of the camera with the absolute

    // transformation of the corresponding node

    cam->mPosition = nd->mTransformation * cam->mPosition;

    cam->mLookAt = 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(nullptr != 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 (!mConfigKeepHierarchy) {

    // now delete all nodes in the scene and build a new

    // flat node graph with a root node and some level 1 children

    aiNode *newRoot = new aiNode();

    newRoot->mName = pScene->mRootNode->mName;

    delete pScene->mRootNode;

    pScene->mRootNode = newRoot;

    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 = new aiNode();

        *nodes = pcNode;

        pcNode->mParent = pScene->mRootNode;

        pcNode->mName = pScene->mMeshes[i]->mName;

        // 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 = new aiNode();

        *nodes = pcNode;

        pcNode->mParent = pScene->mRootNode;

        pcNode->mName.length = ai_snprintf(pcNode->mName.data, AI_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 = new aiNode();

        *nodes = pcNode;

        pcNode->mParent = pScene->mRootNode;

        pcNode->mName.length = ::ai_snprintf(pcNode->mName.data, AI_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 (mConfigNormalize) {

    // 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 ai_real div = std::max(d.x, std::max(d.y, d.z)) * ai_real(0.5);

    d = min + d * (ai_real)0.5;

    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()) {

    ASSIMP_LOG_DEBUG("PretransformVerticesProcess finished");

    ASSIMP_LOG_INFO("Removed ", oldNodes, " nodes and ", oldAnimationChannels, " animation channels (",

        CountNodes(pScene->mRootNode), " output nodes)");

    ASSIMP_LOG_INFO("Kept ", pScene->mNumLights, " lights and ", pScene->mNumCameras, " cameras.");

    ASSIMP_LOG_INFO("Moved ", oldMeshes, " meshes to WCS (number of output meshes: ", pScene->mNumMeshes, ")");

  }

}