assimp.assimp/code/PostProcessing/PretransformVertices.cpp

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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]);
	}
}

static void normalizeVectorArray(aiVector3D *vectorArrayIn, aiVector3D *vectorArrayOut, size_t numVectors) {
	for (size_t i=0; i<numVectors; ++i) {
		vectorArrayOut[i] = vectorArrayIn[i].Normalize();
	}
}

// ------------------------------------------------------------------------------------------------
// 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()) {
			normalizeVectorArray(mesh->mNormals, mesh->mNormals, mesh->mNumVertices);
		}
		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, 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, 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, ")");
	}
}