/*
---------------------------------------------------------------------------
Open Asset Import Library (ASSIMP)
---------------------------------------------------------------------------

Copyright (c) 2006-2008, ASSIMP Development Team

All rights reserved.

Redistribution and use of this software in source and binary forms, 
with or without modification, are permitted provided that the following 
conditions are met:

* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
  materials provided with the distribution.

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  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the ASSIMP Development Team.

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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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*/

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

#include "AssimpPCH.h"
#include "PretransformVertices.h"
#include "ProcessHelper.h"
#include "SceneCombiner.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)
{
}

// ------------------------------------------------------------------------------------------------
// 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 and AI_CONFIG_PP_PTV_NORMALIZE
	configKeepHierarchy = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_KEEP_HIERARCHY,0));
	configNormalize = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_PTV_NORMALIZE,0));
}

// ------------------------------------------------------------------------------------------------
// 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)(unsigned long)pcMesh->mBones;


	const unsigned int iRet = GetMeshVFormatUnique(pcMesh);

	// store the value for later use
	pcMesh->mBones = (aiBone**)(unsigned long)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];
					}
				}
				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];
						pcMeshOut->mBitangents[aiCurrent[AI_PTVS_VERTEX]+n] = m * pcMesh->mBitangents[n];
					}
				}
			}
			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];
				}
			}
			if (mesh->HasTangentsAndBitangents()) {
				for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
					mesh->mTangents[i]   = m * mesh->mTangents[i];
					mesh->mBitangents[i] = m * mesh->mBitangents[i];
				}
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
// 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 0xffffffff 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 = 0xffffffff;
		}
		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);
			}
		}
	}

	// 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);

	// 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]);
				}
			}
		}

		// 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;
		}

		// If no meshes are referenced in the node graph it is possible that we get no output meshes. 
		if (apcOutMeshes.empty())	{		
			throw new ImportErrorException("No output meshes: all meshes are orphaned and are not referenced by nodes");
		}
		else
		{
			// 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;
	}

	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 = ::sprintf(pcNode->mName.data,"mesh_%i",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 = ::sprintf(pcNode->mName.data,"light_%i",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 = ::sprintf(pcNode->mName.data,"cam_%i",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");

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

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

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