assimp.assimp/code/LWOLoader.cpp

/*
---------------------------------------------------------------------------
Open Asset Import Library (ASSIMP)
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Copyright (c) 2006-2008, ASSIMP Development Team

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  following disclaimer.

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*/

/** @file Implementation of the LWO importer class */

#include "AssimpPCH.h"


// internal headers
#include "LWOLoader.h"
#include "MaterialSystem.h"
#include "StringComparison.h"
#include "SGSpatialSort.h"
#include "ByteSwap.h"
#include "ProcessHelper.h"

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
LWOImporter::LWOImporter()
{
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well 
LWOImporter::~LWOImporter()
{
}

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file. 
bool LWOImporter::CanRead( const std::string& pFile, IOSystem* pIOHandler) const
{
	// simple check of file extension is enough for the moment
	std::string::size_type pos = pFile.find_last_of('.');
	// no file extension - can't read
	if( pos == std::string::npos)return false;
	std::string extension = pFile.substr( pos);

	if (extension.length() < 4)return false;
	if (extension[0] != '.')return false;

	if (extension[1] != 'l' && extension[1] != 'L')return false;
	if (extension[2] != 'w' && extension[2] != 'W')return false;
	if (extension[3] != 'o' && extension[3] != 'O')return false;

	return true;
}

// ------------------------------------------------------------------------------------------------
// Setup configuration properties
void LWOImporter::SetupProperties(const Importer* pImp)
{
	configSpeedFlag  = ( 0 != pImp->GetPropertyInteger(AI_CONFIG_FAVOUR_SPEED,0) ? true : false);
	configLayerIndex = pImp->GetPropertyInteger (AI_CONFIG_IMPORT_LWO_ONE_LAYER_ONLY,0xffffffff); 
	configLayerName  = pImp->GetPropertyString  (AI_CONFIG_IMPORT_LWO_ONE_LAYER_ONLY,"");
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure. 
void LWOImporter::InternReadFile( const std::string& pFile, 
	aiScene* pScene, 
	IOSystem* pIOHandler)
{
	boost::scoped_ptr<IOStream> file( pIOHandler->Open( pFile, "rb"));

	// Check whether we can read from the file
	if( file.get() == NULL)
		throw new ImportErrorException( "Failed to open LWO file " + pFile + ".");

	if((this->fileSize = (unsigned int)file->FileSize()) < 12)
		throw new ImportErrorException("LWO: The file is too small to contain the IFF header");

	// allocate storage and copy the contents of the file to a memory buffer
	std::vector< uint8_t > mBuffer(fileSize);
	file->Read( &mBuffer[0], 1, fileSize);
	this->pScene = pScene;

	// determine the type of the file
	uint32_t fileType;
	const char* sz = IFF::ReadHeader(&mBuffer[0],fileType);
	if (sz)throw new ImportErrorException(sz);

	mFileBuffer = &mBuffer[0] + 12;
	fileSize -= 12;

	// create temporary storage on the stack but store pointers to it in the class 
	// instance. Therefore everything will be destructed properly if an exception 
	// is thrown and we needn't take care of that.
	LayerList _mLayers;
	mLayers = &_mLayers;
	TagList _mTags;				
	mTags = &_mTags;
	TagMappingTable _mMapping;	
	mMapping = &_mMapping;
	SurfaceList _mSurfaces;		
	mSurfaces = &_mSurfaces;

	// allocate a default layer
	mLayers->push_back(Layer());
	mCurLayer = &mLayers->back();
	mCurLayer->mName = "<LWODefault>";

	// old lightwave file format (prior to v6)
	if (AI_LWO_FOURCC_LWOB == fileType)
	{
		mIsLWO2 = false;
		this->LoadLWOBFile();
	}

	// new lightwave format
	else if (AI_LWO_FOURCC_LWO2 == fileType)
	{
		mIsLWO2 = true;
		this->LoadLWO2File();
	}

	// we don't know this format
	else 
	{
		char szBuff[5];
		szBuff[0] = (char)(fileType >> 24u);
		szBuff[1] = (char)(fileType >> 16u);
		szBuff[2] = (char)(fileType >> 8u);
		szBuff[3] = (char)(fileType);
		throw new ImportErrorException(std::string("Unknown LWO sub format: ") + szBuff);
	}

	// now, as we have loaded all data, we can resolve cross-referenced tags and clips
	ResolveTags();
	ResolveClips();

	// now process all layers and build meshes and nodes
	std::vector<aiMesh*> apcMeshes;
	std::vector<aiNode*> apcNodes;
	apcNodes.reserve(mLayers->size());
	apcMeshes.reserve(mLayers->size()*std::min(((unsigned int)mSurfaces->size()/2u), 1u));


	unsigned int iDefaultSurface = 0xffffffff; // index of the default surface
	for (LayerList::iterator lit = mLayers->begin(), lend = mLayers->end();
		lit != lend;++lit)
	{
		LWO::Layer& layer = *lit;

		// I don't know whether there could be dummy layers, but it would be possible
		const unsigned int meshStart = (unsigned int)apcMeshes.size();
		if (!layer.mFaces.empty() && !layer.mTempPoints.empty())
		{
			// now sort all faces by the surfaces assigned to them
			typedef std::vector<unsigned int> SortedRep;
			std::vector<SortedRep> pSorted(mSurfaces->size()+1);

			unsigned int i = 0;
			for (FaceList::iterator it = layer.mFaces.begin(), end = layer.mFaces.end();
				it != end;++it,++i)
			{
				unsigned int idx = (*it).surfaceIndex;
				if (idx >= mTags->size())
				{
					DefaultLogger::get()->warn("LWO: Invalid face surface index");
					idx = 0xffffffff;
				}
				if(0xffffffff == idx || 0xffffffff == (idx = _mMapping[idx]))
				{
					if (0xffffffff == iDefaultSurface)
					{
						iDefaultSurface = (unsigned int)mSurfaces->size();
						mSurfaces->push_back(LWO::Surface());
						LWO::Surface& surf = mSurfaces->back();
						surf.mColor.r = surf.mColor.g = surf.mColor.b = 0.6f; 
					}
					idx = iDefaultSurface;
				}
				pSorted[idx].push_back(i);
			}
			if (0xffffffff == iDefaultSurface)pSorted.erase(pSorted.end()-1);

			// now generate output meshes
			for (unsigned int p = 0; p < mSurfaces->size();++p)
				if (!pSorted[p].empty())pScene->mNumMeshes++;

			if (!pScene->mNumMeshes)
				throw new ImportErrorException("LWO: There are no meshes");

			pScene->mMeshes = new aiMesh*[pScene->mNumMeshes];
			for (unsigned int p = 0,i = 0;i < mSurfaces->size();++i)
			{
				SortedRep& sorted = pSorted[i];
				if (sorted.empty())continue;

				// generate the mesh 
				aiMesh* mesh = new aiMesh();
				apcMeshes.push_back(mesh);
				mesh->mNumFaces = (unsigned int)sorted.size();

				// count the number of vertices
				SortedRep::const_iterator it = sorted.begin(), end = sorted.end();
				for (;it != end;++it)
				{
					mesh->mNumVertices += layer.mFaces[*it].mNumIndices;
				}

				aiVector3D* pv = mesh->mVertices = new aiVector3D[mesh->mNumVertices];
				aiFace* pf = mesh->mFaces = new aiFace[mesh->mNumFaces];
				mesh->mMaterialIndex = i;

				// find out which vertex color channels and which texture coordinate
				// channels are really required by the material attached to this mesh
				unsigned int vUVChannelIndices[AI_MAX_NUMBER_OF_TEXTURECOORDS];
				unsigned int vVColorIndices[AI_MAX_NUMBER_OF_COLOR_SETS];

#if _DEBUG
				for (unsigned int mui = 0; mui < AI_MAX_NUMBER_OF_TEXTURECOORDS;++mui )
					vUVChannelIndices[mui] = 0xffffffff;
				for (unsigned int mui = 0; mui < AI_MAX_NUMBER_OF_COLOR_SETS;++mui )
					vVColorIndices[mui] = 0xffffffff;
#endif

				FindUVChannels(_mSurfaces[i],layer,vUVChannelIndices);
				FindVCChannels(_mSurfaces[i],layer,vVColorIndices);

				// allocate storage for UV and CV channels
				aiVector3D* pvUV[AI_MAX_NUMBER_OF_TEXTURECOORDS];
				for (unsigned int mui = 0; mui < AI_MAX_NUMBER_OF_TEXTURECOORDS;++mui )
				{
					if (0xffffffff == vUVChannelIndices[mui])break;
					pvUV[mui] = mesh->mTextureCoords[mui] = new aiVector3D[mesh->mNumVertices];

					// LightWave doesn't support more than 2 UV components
					mesh->mNumUVComponents[0] = 2;
				}
		
				aiColor4D* pvVC[AI_MAX_NUMBER_OF_COLOR_SETS];
				for (unsigned int mui = 0; mui < AI_MAX_NUMBER_OF_COLOR_SETS;++mui)	
				{
					if (0xffffffff == vVColorIndices[mui])break;
					pvVC[mui] = mesh->mColors[mui] = new aiColor4D[mesh->mNumVertices];
				}

				// we would not need this extra array, but the code is much cleaner if we use it
				// FIX: we can use the referrer ID array here. invalidate its contents
				// before we resize it to avoid a unnecessary memcpy 
				std::vector<unsigned int>& smoothingGroups = layer.mPointReferrers;
				smoothingGroups.erase (smoothingGroups.begin(),smoothingGroups.end());
				smoothingGroups.resize(mesh->mNumFaces,0);

				// now convert all faces
				unsigned int vert = 0;
				std::vector<unsigned int>::iterator outIt = smoothingGroups.begin();
				for (it = sorted.begin(); it != end;++it,++outIt)
				{
					const LWO::Face& face = layer.mFaces[*it];
					*outIt = face.smoothGroup;

					// copy all vertices
					for (unsigned int q = 0; q  < face.mNumIndices;++q)
					{
						register unsigned int idx = face.mIndices[q];
						*pv = layer.mTempPoints[idx] + layer.mPivot;
						pv->z *= -1.0f; // DX to OGL
						pv++;

						// process UV coordinates
						for (unsigned int w = 0; w < AI_MAX_NUMBER_OF_TEXTURECOORDS;++w)	
						{
							if (0xffffffff == vUVChannelIndices[w])break;
							aiVector3D*& pp = pvUV[w];
							const aiVector2D& src = ((aiVector2D*)&layer.mUVChannels[vUVChannelIndices[w]].rawData[0])[idx];
							pp->x = src.x;
							pp->y = 1.f-src.y; // DX to OGL
							pp++;
						}

						// process vertex colors
						for (unsigned int w = 0; w < AI_MAX_NUMBER_OF_COLOR_SETS;++w)	
						{
							if (0xffffffff == vVColorIndices[w])break;
							*(pvVC[w])++ = ((aiColor4D*)&layer.mVColorChannels[vVColorIndices[w]].rawData[0])[idx];
						}

#if 0
						// process vertex weights - not yet supported
						for (unsigned int w = 0; w < layer.mWeightChannels.size();++w)
						{
						}
#endif
						face.mIndices[q] = vert + (face.mNumIndices-q-1);
					}
					vert += face.mNumIndices;

					pf->mIndices = face.mIndices;
					pf->mNumIndices = face.mNumIndices;
					unsigned int** p = (unsigned int**)&face.mIndices;*p = NULL; // make sure it won't be deleted
					pf++;
				}

				// compute normal vectors for the mesh - we can't use our GenSmoothNormal-Step here
				// since it wouldn't handle smoothing groups correctly
				ComputeNormals(mesh,smoothingGroups,_mSurfaces[i]);

				++p;
			}
		}

		// generate nodes to render the mesh. Store the parent index
		// in the mParent member of the nodes
		aiNode* pcNode = new aiNode();
		apcNodes.push_back(pcNode);
		pcNode->mName.Set(layer.mName);
		pcNode->mParent = (aiNode*)(uintptr_t)(layer.mParent);
		pcNode->mNumMeshes = (unsigned int)apcMeshes.size() - meshStart;
		pcNode->mMeshes = new unsigned int[pcNode->mNumMeshes];
		for (unsigned int p = 0; p < pcNode->mNumMeshes;++p)
			pcNode->mMeshes[p] = p + meshStart;
	}

	// the RemoveRedundantMaterials step will clean this up later
	pScene->mMaterials = new aiMaterial*[pScene->mNumMaterials = (unsigned int)mSurfaces->size()];
	for (unsigned int mat = 0; mat < pScene->mNumMaterials;++mat)
	{
		MaterialHelper* pcMat = new MaterialHelper();
		pScene->mMaterials[mat] = pcMat;
		ConvertMaterial((*mSurfaces)[mat],pcMat);
	}

	// copy the meshes to the output structure
	if (apcMeshes.size()) // shouldn't occur, just to be sure we don't crash
	{
		pScene->mMeshes = new aiMesh*[ pScene->mNumMeshes = (unsigned int)apcMeshes.size() ];
		::memcpy(pScene->mMeshes,&apcMeshes[0],pScene->mNumMeshes*sizeof(void*));
	}

	// generate the final node graph
	GenerateNodeGraph(apcNodes);
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::ComputeNormals(aiMesh* mesh, const std::vector<unsigned int>& smoothingGroups,
	const LWO::Surface& surface)
{
	// allocate output storage
	mesh->mNormals = new aiVector3D[mesh->mNumVertices];

	// First generate per-face normals
	aiVector3D* out;
	std::vector<aiVector3D> faceNormals;

	if (!surface.mMaximumSmoothAngle)
		out = mesh->mNormals;
	else
	{
		faceNormals.resize(mesh->mNumVertices);
		out = &faceNormals[0];
	}

	aiFace* begin = mesh->mFaces, *const end = mesh->mFaces+mesh->mNumFaces;
	for (; begin != end; ++begin)
	{
		aiFace& face = *begin;

		// LWO doc: "the normal is defined as the cross product of the first and last edges"
		aiVector3D* pV1 = mesh->mVertices + face.mIndices[0];
		aiVector3D* pV2 = mesh->mVertices + face.mIndices[1];
		aiVector3D* pV3 = mesh->mVertices + face.mIndices[face.mNumIndices-1];

		aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).Normalize();
		for (unsigned int i = 0; i < face.mNumIndices;++i)
			out[face.mIndices[i]] = vNor;
	}
	if (!surface.mMaximumSmoothAngle)return;
	const float posEpsilon = ComputePositionEpsilon(mesh);
	
	// now generate the spatial sort tree
	SGSpatialSort sSort;
	std::vector<unsigned int>::const_iterator it = smoothingGroups.begin();
	for( begin =  mesh->mFaces; begin != end; ++begin, ++it)
	{
		aiFace& face = *begin;
		for (unsigned int i = 0; i < face.mNumIndices;++i)
		{
			register unsigned int tt = face.mIndices[i];
			sSort.Add(mesh->mVertices[tt],tt,*it);
		}
	}
	// sort everything - this takes O(nlogn) time
	sSort.Prepare();
	std::vector<unsigned int> poResult;
	poResult.reserve(20);

	// generate vertex normals. We have O(logn) for the binary lookup, which we need
	// for n elements, thus the EXPECTED complexity is O(nlogn)
	if (surface.mMaximumSmoothAngle < 3.f && !configSpeedFlag)
	{
		const float fLimit = cos(surface.mMaximumSmoothAngle);

		for( begin =  mesh->mFaces, it = smoothingGroups.begin(); begin != end; ++begin, ++it)
		{
			register unsigned int sg = *it;

			aiFace& face = *begin;
			unsigned int* beginIdx = face.mIndices, *const endIdx = face.mIndices+face.mNumIndices;
			for (; beginIdx != endIdx; ++beginIdx)
			{
				register unsigned int idx = *beginIdx;
				sSort.FindPositions(mesh->mVertices[idx],sg,posEpsilon,poResult,true);

				std::vector<unsigned int>::const_iterator a, end = poResult.end();

				aiVector3D vNormals;
				for (a =  poResult.begin();a != end;++a)
				{
					const aiVector3D& v = faceNormals[*a];
					if (v * faceNormals[idx] < fLimit)continue;
					vNormals += v;
				}
				vNormals.Normalize();
				mesh->mNormals[idx] = vNormals;
			}
		}
	}
	else // faster code path in case there is no smooth angle
	{
		std::vector<bool> vertexDone(mesh->mNumVertices,false);

		for( begin =  mesh->mFaces, it = smoothingGroups.begin(); begin != end; ++begin, ++it)
		{
			register unsigned int sg = *it;

			aiFace& face = *begin;
			unsigned int* beginIdx = face.mIndices, *const endIdx = face.mIndices+face.mNumIndices;
			for (; beginIdx != endIdx; ++beginIdx)
			{
				register unsigned int idx = *beginIdx;

				if (vertexDone[idx])continue;
				sSort.FindPositions(mesh->mVertices[idx],sg,posEpsilon,poResult,true);

				std::vector<unsigned int>::const_iterator a, end = poResult.end();

				aiVector3D vNormals;
				for (a =  poResult.begin();a != end;++a)
				{
					const aiVector3D& v = faceNormals[*a];
					vNormals += v;
				}
				vNormals.Normalize();
				for (a =  poResult.begin();a != end;++a)
				{
					mesh->mNormals[*a] = vNormals;
					vertexDone[*a] = true;
				}
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::AddChildren(aiNode* node, uintptr_t parent, std::vector<aiNode*>& apcNodes)
{
	for (uintptr_t i  = 0; i < (uintptr_t)apcNodes.size();++i)
	{
		if (i == parent)continue;
		if (apcNodes[i] && (uintptr_t)apcNodes[i]->mParent == parent)++node->mNumChildren;
	}

	if (node->mNumChildren)
	{
		node->mChildren = new aiNode* [ node->mNumChildren ];
		for (uintptr_t i = 0, p = 0; i < (uintptr_t)apcNodes.size();++i)
		{
			if (i == parent)continue;

			if (apcNodes[i] && parent == (uintptr_t)(apcNodes[i]->mParent))
			{
				node->mChildren[p++] = apcNodes[i];
				apcNodes[i]->mParent = node;

				// recursively add more children
				AddChildren(apcNodes[i],i,apcNodes);
				apcNodes[i] = NULL;
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::GenerateNodeGraph(std::vector<aiNode*>& apcNodes)
{
	// now generate the final nodegraph - generate a root node
	pScene->mRootNode = new aiNode();
	pScene->mRootNode->mName.Set("<LWORoot>");
	AddChildren(pScene->mRootNode,0,apcNodes);

	unsigned int extra = 0;
	for (unsigned int i = 0; i < apcNodes.size();++i)
		if (apcNodes[i] && apcNodes[i]->mNumMeshes)++extra;

	if (extra)
	{
		// we need to add extra nodes to the root
		const unsigned int newSize = extra + pScene->mRootNode->mNumChildren;
		aiNode** const apcNewNodes = new aiNode*[newSize];
		if((extra = pScene->mRootNode->mNumChildren))
			::memcpy(apcNewNodes,pScene->mRootNode->mChildren,extra*sizeof(void*));

		aiNode** cc = apcNewNodes+extra;
		for (unsigned int i = 0; i < apcNodes.size();++i)
		{
			if (apcNodes[i] && apcNodes[i]->mNumMeshes)
			{
				*cc++ = apcNodes[i];
				apcNodes[i]->mParent = pScene->mRootNode;

				// recursively add more children
				AddChildren(apcNodes[i],i,apcNodes);
				apcNodes[i] = NULL;
			}
		}
		delete[] pScene->mRootNode->mChildren;
		pScene->mRootNode->mChildren	= apcNewNodes;
		pScene->mRootNode->mNumChildren	= newSize;
	}
	if (!pScene->mRootNode->mNumChildren)throw new ImportErrorException("LWO: Unable to build a valid node graph");

	// remove a single root node
	// TODO: implement directly in the above loop, no need to deallocate here
	if (1 == pScene->mRootNode->mNumChildren)
	{
		aiNode* pc = pScene->mRootNode->mChildren[0];
		pc->mParent = pScene->mRootNode->mChildren[0] = NULL;
		delete pScene->mRootNode;
		pScene->mRootNode = pc;
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::ResolveTags()
{
	// --- this function is used for both LWO2 and LWOB
	mMapping->resize(mTags->size(),0xffffffff);
	for (unsigned int a = 0; a  < mTags->size();++a)
	{
		for (unsigned int i = 0; i < mSurfaces->size();++i)
		{
			const std::string& c = (*mTags)[a];
			const std::string& d = (*mSurfaces)[i].mName;
			if (!ASSIMP_stricmp(c,d))
			{
				(*mMapping)[a] = i;
				break;
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::ResolveClips()
{
	for( unsigned int i = 0; i < mClips.size();++i)
	{
		Clip& clip = mClips[i];
		if (Clip::REF == clip.type)
		{
			if (clip.clipRef >= mClips.size())
			{
				DefaultLogger::get()->error("LWO2: Clip referrer index is out of range");
				clip.clipRef = 0;
			}
			Clip& dest = mClips[clip.clipRef];
			if (Clip::REF == dest.type)
			{
				DefaultLogger::get()->error("LWO2: Clip references another clip reference");
				clip.type = Clip::UNSUPPORTED;
			}
			else
			{
				clip.path = dest.path;
				clip.type = dest.type;
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::AdjustTexturePath(std::string& out)
{
	// --- this function is used for both LWO2 and LWOB
	if (!mIsLWO2 && ::strstr(out.c_str(), "(sequence)"))
	{
		// remove the (sequence) and append 000
		DefaultLogger::get()->info("LWOB: Sequence of animated texture found. It will be ignored");
		out = out.substr(0,out.length()-10) + "000";
	}

	// format: drive:path/file - we need to insert a slash after the drive
	std::string::size_type n = out.find_first_of(':');
	if (std::string::npos != n)
	{
		out.insert(n+1,"/");
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWOTags(unsigned int size)
{
	// --- this function is used for both LWO2 and LWOB

	const char* szCur = (const char*)mFileBuffer, *szLast = szCur;
	const char* const szEnd = szLast+size;
	while (szCur < szEnd)
	{
		if (!(*szCur))
		{
			const unsigned int len = (unsigned int)(szCur-szLast);
			mTags->push_back(std::string(szLast,len));
			szCur += len & 1;
			szLast = szCur;
		}
		szCur++;
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWOPoints(unsigned int length)
{
	// --- this function is used for both LWO2 and LWOB but for
	// LWO2 we need to allocate 25% more storage - it could be we'll 
	// need to duplicate some points later.
	register unsigned int regularSize = (unsigned int)mCurLayer->mTempPoints.size() + length / 12;
	if (mIsLWO2)
	{
		mCurLayer->mTempPoints.reserve	( regularSize + (regularSize>>2u) );
		mCurLayer->mTempPoints.resize	( regularSize );

		// initialize all point referrers with the default values
		mCurLayer->mPointReferrers.reserve	( regularSize + (regularSize>>2u) );
		mCurLayer->mPointReferrers.resize	( regularSize, 0xffffffff );
	}
	else mCurLayer->mTempPoints.resize( regularSize );

	// perform endianess conversions
#ifndef AI_BUILD_BIG_ENDIAN
	for (unsigned int i = 0; i < length>>2;++i)
		ByteSwap::Swap4( mFileBuffer + (i << 2));
#endif
	::memcpy(&mCurLayer->mTempPoints[0],mFileBuffer,length);
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2Polygons(unsigned int length)
{
	LE_NCONST uint16_t* const end	= (LE_NCONST uint16_t*)(mFileBuffer+length);
	uint32_t type = GetU4();

	if (type != AI_LWO_FACE)
	{
		DefaultLogger::get()->warn("LWO2: Only POLS.FACE chunks are supported.");
		return;
	}

	// first find out how many faces and vertices we'll finally need
	uint16_t* cursor		= (uint16_t*)mFileBuffer;

	unsigned int iNumFaces = 0,iNumVertices = 0;
	CountVertsAndFacesLWO2(iNumVertices,iNumFaces,cursor,end);

	// allocate the output array and copy face indices
	if (iNumFaces)
	{
		cursor = (uint16_t*)mFileBuffer;

		mCurLayer->mFaces.resize(iNumFaces);
		FaceList::iterator it = mCurLayer->mFaces.begin();
		CopyFaceIndicesLWO2(it,cursor,end);
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::CountVertsAndFacesLWO2(unsigned int& verts, unsigned int& faces,
	uint16_t*& cursor, const uint16_t* const end, unsigned int max)
{
	while (cursor < end && max--)
	{
		AI_LSWAP2P(cursor);
		uint16_t numIndices = *cursor++;
		numIndices &= 0x03FF;
		verts += numIndices;++faces;

		for(uint16_t i = 0; i < numIndices; i++)
			ReadVSizedIntLWO2((uint8_t*&)cursor);
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::CopyFaceIndicesLWO2(FaceList::iterator& it,
	uint16_t*& cursor, 
	const uint16_t* const end)
{
	while (cursor < end)
	{
		LWO::Face& face = *it;++it;
		if((face.mNumIndices = (*cursor++) & 0x03FF)) // swapping has already been done
		{
			face.mIndices = new unsigned int[face.mNumIndices];
			for(unsigned int i = 0; i < face.mNumIndices; i++)
			{
				face.mIndices[i] = ReadVSizedIntLWO2((uint8_t*&)cursor) + mCurLayer->mPointIDXOfs;
				if(face.mIndices[i] > mCurLayer->mTempPoints.size())
				{
					DefaultLogger::get()->warn("LWO2: face index is out of range");
					face.mIndices[i] = (unsigned int)mCurLayer->mTempPoints.size()-1;
				}
			}
		}
		else DefaultLogger::get()->warn("LWO2: face has 0 indices");
	}
}


// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2PolygonTags(unsigned int length)
{
	LE_NCONST uint8_t* const end = mFileBuffer+length;

	AI_LWO_VALIDATE_CHUNK_LENGTH(length,PTAG,4);
	uint32_t type = GetU4();

	if (type != AI_LWO_SURF && type != AI_LWO_SMGP)
		return;

	while (mFileBuffer < end)
	{
		unsigned int i = ReadVSizedIntLWO2(mFileBuffer) + mCurLayer->mFaceIDXOfs;
		unsigned int j = GetU2();

		if (i >= mCurLayer->mFaces.size())
		{
			DefaultLogger::get()->warn("LWO2: face index in PTAG is out of range");
			continue;
		}

		switch (type)
		{
		case AI_LWO_SURF:
			mCurLayer->mFaces[i].surfaceIndex = j;
			break;
		case AI_LWO_SMGP:
			mCurLayer->mFaces[i].smoothGroup = j;
			break;
		};
	}
}

// ------------------------------------------------------------------------------------------------
template <class T>
VMapEntry* FindEntry(std::vector< T >& list,const std::string& name, bool perPoly)
{
	for (typename std::vector< T >::iterator it = list.begin(), end = list.end();
		 it != end; ++it)
	{
		if ((*it).name == name)
		{
			if (!perPoly)
			{
				DefaultLogger::get()->warn("LWO2: Found two VMAP sections with equal names");
			}
			return &(*it);
		}
	}
	list.push_back( T() );
	VMapEntry* p = &list.back();
	p->name = name;
	return p;
}

// ------------------------------------------------------------------------------------------------
template <class T>
void CreateNewEntry(std::vector< T >& list, unsigned int srcIdx)
{
	for (typename std::vector< T >::iterator 
		it =  list.begin(), end = list.end();
		it != end;++it)
	{
		T& chan = *it;

		chan.abAssigned[srcIdx] = true;
		chan.abAssigned.resize(chan.abAssigned.size()+1,false);

		for (unsigned int a = 0; a < chan.dims;++a)
			chan.rawData.push_back(chan.rawData[srcIdx*chan.dims+a]);
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::DoRecursiveVMAPAssignment(VMapEntry* base, unsigned int numRead, 
	unsigned int idx, float* data)
{
	ai_assert(NULL != data);
	LWO::ReferrerList& refList	= mCurLayer->mPointReferrers;
	unsigned int i;

	base->abAssigned[idx] = true;
	for (i = 0; i < numRead;++i) 
		base->rawData[idx*base->dims+i]= data[i];

	if (0xffffffff != (i = refList[idx]))
		DoRecursiveVMAPAssignment(base,numRead,i,data);
}

// ------------------------------------------------------------------------------------------------
void AddToSingleLinkedList(ReferrerList& refList, unsigned int srcIdx, unsigned int destIdx)
{
	if(0xffffffff == refList[srcIdx])
	{
		refList[srcIdx] = destIdx;
		return;
	}
	AddToSingleLinkedList(refList,refList[srcIdx],destIdx);
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2VertexMap(unsigned int length, bool perPoly)
{
	LE_NCONST uint8_t* const end = mFileBuffer+length;

	AI_LWO_VALIDATE_CHUNK_LENGTH(length,VMAP,6);
	unsigned int type = GetU4();
	unsigned int dims = GetU2();

	VMapEntry* base;

	// read the name of the vertex map 
	std::string name;
	GetS0(name,length);

	switch (type)
	{
	case AI_LWO_TXUV:
		if (dims != 2)
		{
			DefaultLogger::get()->warn("LWO2: Found UV channel with != 2 components"); 
		}
		base = FindEntry(mCurLayer->mUVChannels,name,perPoly);
		break;
	case AI_LWO_WGHT:
		if (dims != 1)
		{
			DefaultLogger::get()->warn("LWO2: found vertex weight map with != 1 components"); 
		}
		base = FindEntry(mCurLayer->mWeightChannels,name,perPoly);
		break;
	case AI_LWO_RGB:
	case AI_LWO_RGBA:
		if (dims != 3 && dims != 4)
		{
			DefaultLogger::get()->warn("LWO2: found vertex color map with != 3&4 components"); 
		}
		base = FindEntry(mCurLayer->mVColorChannels,name,perPoly);
		break;
	default: return;
	};
	base->Allocate((unsigned int)mCurLayer->mTempPoints.size());

	// now read all entries in the map
	type = std::min(dims,base->dims); 
	const unsigned int diff = (dims - type)<<2;

	LWO::FaceList& list	= mCurLayer->mFaces;
	LWO::PointList& pointList = mCurLayer->mTempPoints;
	LWO::ReferrerList& refList = mCurLayer->mPointReferrers;

	float temp[4];

	const unsigned int numPoints = (unsigned int)pointList.size();
	const unsigned int numFaces  = (unsigned int)list.size();

	while (mFileBuffer < end)
	{
		unsigned int idx = ReadVSizedIntLWO2(mFileBuffer) + mCurLayer->mPointIDXOfs;
		if (idx >= numPoints)
		{
			DefaultLogger::get()->warn("LWO2: vertex index in vmap/vmad is out of range");
			mFileBuffer += base->dims*4;continue;
		}
		if (perPoly)
		{
			unsigned int polyIdx = ReadVSizedIntLWO2(mFileBuffer) + mCurLayer->mFaceIDXOfs;
			if (base->abAssigned[idx])
			{
				// we have already a VMAP entry for this vertex - thus
				// we need to duplicate the corresponding polygon.
				if (polyIdx >= numFaces)
				{
					DefaultLogger::get()->warn("LWO2: VMAD polygon index is out of range");
					mFileBuffer += base->dims*4;continue;
				}

				LWO::Face& src = list[polyIdx];
				refList.resize(refList.size()+src.mNumIndices, 0xffffffff);

				// generate new vertex positions
				for (unsigned int i = 0; i < src.mNumIndices;++i)
				{
					register unsigned int srcIdx = src.mIndices[i];
					if (idx == srcIdx)
					{
						idx = (unsigned int)pointList.size();
					}
					src.mIndices[i] = (unsigned int)pointList.size();

					// store the index of the new vertex in the old vertex
					// so we get a single linked list we can traverse in
					// only one direction
					AddToSingleLinkedList(refList,srcIdx,src.mIndices[i]);
					pointList.push_back(pointList[srcIdx]);

					CreateNewEntry(mCurLayer->mVColorChannels,	srcIdx );
					CreateNewEntry(mCurLayer->mUVChannels,		srcIdx );
					CreateNewEntry(mCurLayer->mWeightChannels,	srcIdx );
				}
			}
		}
		for (unsigned int l = 0; l < type;++l)
			temp[l] = GetF4();

		DoRecursiveVMAPAssignment(base,type,idx, temp);
		mFileBuffer += diff;
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2Clip(unsigned int length)
{
	AI_LWO_VALIDATE_CHUNK_LENGTH(length,CLIP,10);

	mClips.push_back(LWO::Clip());
	LWO::Clip& clip = mClips.back();

	// first - get the index of the clip
	clip.idx = GetU4();

	IFF::SubChunkHeader* const head = IFF::LoadSubChunk(mFileBuffer);
	switch (head->type)
	{
	case AI_LWO_STIL:
		GetS0(clip.path,head->length);
		clip.type = Clip::STILL;
		break;

	case AI_LWO_ISEQ:
		{
			uint8_t digits = GetU1();  mFileBuffer++;
			int16_t offset = GetU2();  mFileBuffer+=4;
			int16_t start  = GetU2();  mFileBuffer+=4;

			std::string s;std::stringstream ss;
			GetS0(s,head->length);
      head->length -= (unsigned int)s.length()+1;
			ss << s;
			ss << std::setw(digits) << offset + start;
			GetS0(s,head->length);
			ss << s;
			clip.path = ss.str();
			clip.type = Clip::SEQ;
		}
		break;

	case AI_LWO_STCC:
		DefaultLogger::get()->warn("LWO2: Color shifted images are not supported");
		break;

	case AI_LWO_ANIM:
		DefaultLogger::get()->warn("LWO2: Animated textures are not supported");
		break;

	case AI_LWO_XREF:
		clip.type = Clip::REF;
		clip.clipRef = GetU4();
		break;

	default:
		DefaultLogger::get()->warn("LWO2: Encountered unknown CLIP subchunk");
	}
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2File()
{
	LE_NCONST uint8_t* const end = mFileBuffer + fileSize;
	while (true)
	{
		if (mFileBuffer + sizeof(IFF::ChunkHeader) > end)break;
		IFF::ChunkHeader* const head = IFF::LoadChunk(mFileBuffer);

		if (mFileBuffer + head->length > end)
		{
			throw new ImportErrorException("LWO2: Chunk length points behind the file");
			break;
		}
		uint8_t* const next = mFileBuffer+head->length;
		unsigned int iUnnamed = 0;
		switch (head->type)
		{
			// new layer
		case AI_LWO_LAYR:
			{
				// add a new layer to the list ....
				mLayers->push_back ( LWO::Layer() );
				LWO::Layer& layer = mLayers->back();
				mCurLayer = &layer;

				AI_LWO_VALIDATE_CHUNK_LENGTH(head->length,LAYR,16);

				// and parse its properties, e.g. the pivot point
				mFileBuffer += 2;
				mCurLayer->mPivot.x = GetF4();
				mCurLayer->mPivot.y = GetF4();
				mCurLayer->mPivot.z = GetF4();
				mFileBuffer += 2;
				GetS0(layer.mName,head->length-16);

				// if the name is empty, generate a default name
				if (layer.mName.empty())
				{
					char buffer[128]; // should be sufficiently large
					::sprintf(buffer,"Layer_%i", iUnnamed++);
					layer.mName = buffer;
				}

				if (mFileBuffer + 2 <= next)
					layer.mParent = GetU2();

				break;
			}

			// vertex list
		case AI_LWO_PNTS:
			{
				unsigned int old = (unsigned int)mCurLayer->mTempPoints.size();
				LoadLWOPoints(head->length);
				mCurLayer->mPointIDXOfs = old;
				break;
			}
			// vertex tags
		case AI_LWO_VMAD:
			if (mCurLayer->mFaces.empty())
			{
				DefaultLogger::get()->warn("LWO2: Unexpected VMAD chunk");
				break;
			}
			// --- intentionally no break here
		case AI_LWO_VMAP:
			{
				if (mCurLayer->mTempPoints.empty())
					DefaultLogger::get()->warn("LWO2: Unexpected VMAP chunk");
				else LoadLWO2VertexMap(head->length,head->type == AI_LWO_VMAD);
				break;
			}
			// face list
		case AI_LWO_POLS:
			{
				unsigned int old = (unsigned int)mCurLayer->mFaces.size();
				LoadLWO2Polygons(head->length);
				mCurLayer->mFaceIDXOfs = old;
				break;
			}
			// polygon tags 
		case AI_LWO_PTAG:
			{
				if (mCurLayer->mFaces.empty())
					DefaultLogger::get()->warn("LWO2: Unexpected PTAG");
				else LoadLWO2PolygonTags(head->length);
				break;
			}
			// list of tags
		case AI_LWO_TAGS:
			{
				if (!mTags->empty())
					DefaultLogger::get()->warn("LWO2: SRFS chunk encountered twice");
				else LoadLWOTags(head->length);
				break;
			}

			// surface chunk
		case AI_LWO_SURF:
			{
				LoadLWO2Surface(head->length);
				break;
			}

			// clip chunk
		case AI_LWO_CLIP:
			{
				LoadLWO2Clip(head->length);
				break;
			}
		}
		mFileBuffer = next;
	}
}