assimp.assimp/code/PlyLoader.cpp

/** @file Implementation of the PLY importer class */
#include "PLYLoader.h"
#include "MaterialSystem.h"

#include "../include/IOStream.h"
#include "../include/IOSystem.h"
#include "../include/aiMesh.h"
#include "../include/aiScene.h"
#include "../include/aiAssert.h"

#include <boost/scoped_ptr.hpp>

using namespace Assimp;


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

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

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file. 
bool PLYImporter::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] != 'p' && extension[1] != 'P')return false;
	if (extension[2] != 'l' && extension[2] != 'L')return false;
	if (extension[3] != 'y' && extension[3] != 'Y')return false;

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

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

	// check whether the ply file is large enough to contain
	// at least the file header
	size_t fileSize = file->FileSize();
	if( fileSize < 10)
	{
		throw new ImportErrorException( ".ply File is too small.");
	}

	// allocate storage and copy the contents of the file to a memory buffer
	// (terminate it with zero)
	this->mBuffer = new unsigned char[fileSize+1];
	file->Read( (void*)mBuffer, 1, fileSize);
	this->mBuffer[fileSize] = '\0';

	// the beginning of the file must be PLY
	if (this->mBuffer[0] != 'P' && this->mBuffer[0] != 'p' ||
		this->mBuffer[1] != 'L' && this->mBuffer[1] != 'l' ||
		this->mBuffer[2] != 'Y' && this->mBuffer[2] != 'y')
	{
		throw new ImportErrorException( "Invalid .ply file: Magic number \'ply\' is no there");
	}
	char* szMe = (char*)&this->mBuffer[3];
	SkipSpacesAndLineEnd(szMe,(const char**)&szMe);
	
	// determine the format of the file data
	PLY::DOM sPlyDom;
	if (0 == ASSIMP_strincmp(szMe,"format",6) && IsSpace(*(szMe+6)))
	{
		szMe += 7;
		if (0 == ASSIMP_strincmp(szMe,"ascii",5) && IsSpace(*(szMe+5)))
		{
			szMe += 6;
			SkipLine(szMe,(const char**)&szMe);
			if(!PLY::DOM::ParseInstance(szMe,&sPlyDom))
			{
				throw new ImportErrorException( "Invalid .ply file: Unable to build DOM (#1)");
			}
		}
		else if (0 == ASSIMP_strincmp(szMe,"binary_",7))
		{
			bool bIsBE = false;

			// binary_little_endian
			// binary_big_endian
			szMe += 7;
#if (defined AI_BUILD_BIG_ENDIAN)
			if ('l' == *szMe || 'L' == *szMe)bIsBE = true;
#else
			if ('b' == *szMe || 'B' == *szMe)bIsBE = true;
#endif // ! AI_BUILD_BIG_ENDIAN

			// skip the line, parse the rest of the header and build the DOM
			SkipLine(szMe,(const char**)&szMe);
			if(!PLY::DOM::ParseInstanceBinary(szMe,&sPlyDom,bIsBE))
			{
				throw new ImportErrorException( "Invalid .ply file: Unable to build DOM (#2)");
			}
		}
		else
		{
			throw new ImportErrorException( "Invalid .ply file: Unknown file format");
		}
	}
	else
	{
		throw new ImportErrorException( "Invalid .ply file: Missing format specification");
	}
	this->pcDOM = &sPlyDom;

	// now load a list of vertices. This must be sucessfull in order to procede
	std::vector<aiVector3D> avPositions;
	this->LoadVertices(&avPositions,false);

	if (avPositions.empty())
	{
		throw new ImportErrorException( "Invalid .ply file: No vertices found");
	}

	// now load a list of normals. 
	std::vector<aiVector3D> avNormals;
	this->LoadVertices(&avNormals,true);

	// load the face list
	std::vector<PLY::Face> avFaces;
	this->LoadFaces(&avFaces);

	// if no face list is existing we assume that the vertex
	// list is containing a list of triangles
	if (avFaces.empty())
	{
		if (avPositions.size() < 3)
		{
			throw new ImportErrorException( "Invalid .ply file: Not enough vertices to build "
				"a face list. ");
		}

		unsigned int iNum = avPositions.size() / 3;
		for (unsigned int i = 0; i< iNum;++i)
		{
			PLY::Face sFace;
			sFace.mIndices.push_back((iNum*3));
			sFace.mIndices.push_back((iNum*3)+1);
			sFace.mIndices.push_back((iNum*3)+2);
			avFaces.push_back(sFace);
		}
	}

	// now load a list of all materials
	std::vector<MaterialHelper*> avMaterials;
	this->LoadMaterial(&avMaterials);

	// now load a list of all vertex color channels
	std::vector<aiColor4D> avColors;
	this->LoadVertexColor(&avColors);

	// now replace the default material in all faces and validate all material indices
	this->ReplaceDefaultMaterial(&avFaces,&avMaterials);

	// now convert this to a list of aiMesh instances
	std::vector<aiMesh*> avMeshes;
	this->ConvertMeshes(&avFaces,&avPositions,&avNormals,
		&avColors,&avMaterials,&avMeshes);

	if (avMeshes.empty())
	{
		throw new ImportErrorException( "Invalid .ply file: Unable to extract mesh data ");
	}

	// now generate the output scene object. Fill the material list
	pScene->mNumMaterials = avMaterials.size();
	pScene->mMaterials = new aiMaterial*[pScene->mNumMaterials];
	for (unsigned int i = 0; i < pScene->mNumMaterials;++i)
		pScene->mMaterials[i] = avMaterials[i];

	// fill the mesh list
	pScene->mNumMeshes = avMeshes.size();
	pScene->mMeshes = new aiMesh*[pScene->mNumMeshes];
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
		pScene->mMeshes[i] = avMeshes[i];

	// generate a simple node structure
	pScene->mRootNode = new aiNode();
	pScene->mRootNode->mNumMeshes = pScene->mNumMeshes;
	pScene->mRootNode->mMeshes = new unsigned int[pScene->mNumMeshes];

	for (unsigned int i = 0; i < pScene->mRootNode->mNumMeshes;++i)
		pScene->mRootNode->mMeshes[i] = i;

	// delete the file buffer
	delete[] this->mBuffer;

	// DOM is lying on the stack, will be deconstructed automatically
	return;
}
// ------------------------------------------------------------------------------------------------
void PLYImporter::ConvertMeshes(std::vector<PLY::Face>* avFaces,
	const std::vector<aiVector3D>*			avPositions,
	const std::vector<aiVector3D>*			avNormals,
	const std::vector<aiColor4D>*			avColors,
	const std::vector<MaterialHelper*>*		avMaterials,
	std::vector<aiMesh*>* avOut)
{
	ai_assert(NULL != avFaces);
	ai_assert(NULL != avPositions);
	ai_assert(NULL != avMaterials);

	// split by materials
	std::vector<unsigned int>* aiSplit = new std::vector<unsigned int>[
		avMaterials->size()];

	unsigned int iNum = 0;
	for (std::vector<PLY::Face>::const_iterator
		i =  avFaces->begin();
		i != avFaces->end();++i,++iNum)
	{
		// index has already been checked
		aiSplit[(*i).iMaterialIndex].push_back(iNum);
	}
	// now generate submeshes
	for (unsigned int p = 0; p < avMaterials->size();++p)
	{
		if (aiSplit[p].size() != 0)
		{
			// allocate the mesh object
			aiMesh* p_pcOut = new aiMesh();
			p_pcOut->mMaterialIndex = p;

			p_pcOut->mNumFaces = aiSplit[p].size();
			p_pcOut->mFaces = new aiFace[aiSplit[p].size()];

			// at first we need to determine the size of the output vector array
			unsigned int iNum = 0;
			for (unsigned int i = 0; i < aiSplit[p].size();++i)
			{
				iNum += (*avFaces)[aiSplit[p][i]].mIndices.size();
			}
			p_pcOut->mNumVertices = iNum;
			p_pcOut->mVertices = new aiVector3D[iNum];

			if (!avColors->empty())
				p_pcOut->mColors[0] = new aiColor4D[iNum];
			if (!avNormals->empty())
				p_pcOut->mNormals = new aiVector3D[iNum];

			// add all faces
			iNum = 0;
			unsigned int iVertex = 0;
			for (std::vector<unsigned int>::const_iterator
				i =  aiSplit[p].begin();
				i != aiSplit[p].end();++i,++iNum)
			{
				p_pcOut->mFaces[iNum].mNumIndices = (*avFaces)[*i].mIndices.size(); 
				p_pcOut->mFaces[iNum].mIndices = new unsigned int[p_pcOut->mFaces[iNum].mNumIndices];

				// build an unique set of vertices/colors for this face
				// hardcode all combinations to speedup this piece of code
				if (!avColors->empty())
				{
					if (!avNormals->empty())
					{
						for (unsigned int q = 0; q <  p_pcOut->mFaces[iNum].mNumIndices;++q)
						{
							p_pcOut->mFaces[iNum].mIndices[q] = iVertex;
							p_pcOut->mVertices[iVertex]		= (*avPositions)[(*avFaces)[*i].mIndices[q]];
							p_pcOut->mColors[0][iVertex]	= (*avColors)[(*avFaces)[*i].mIndices[q]];
							p_pcOut->mNormals[iVertex]		= (*avNormals)[(*avFaces)[*i].mIndices[q]];
							iVertex++;
						}
					}
					else
					{
						for (unsigned int q = 0; q <  p_pcOut->mFaces[iNum].mNumIndices;++q)
						{
							p_pcOut->mFaces[iNum].mIndices[q] = iVertex;
							p_pcOut->mVertices[iVertex]		= (*avPositions)[(*avFaces)[*i].mIndices[q]];
							p_pcOut->mColors[0][iVertex]	= (*avColors)[(*avFaces)[*i].mIndices[q]];
							iVertex++;
						}
					}
				}
				else
				{
					if (!avNormals->empty())
					{
						for (unsigned int q = 0; q <  p_pcOut->mFaces[iNum].mNumIndices;++q)
						{
							p_pcOut->mFaces[iNum].mIndices[q] = iVertex;
							p_pcOut->mVertices[iVertex]		= (*avPositions)[(*avFaces)[*i].mIndices[q]];
							p_pcOut->mNormals[iVertex]		= (*avNormals)[(*avFaces)[*i].mIndices[q]];
							iVertex++;
						}
					}
					else
					{
						for (unsigned int q = 0; q <  p_pcOut->mFaces[iNum].mNumIndices;++q)
						{
							p_pcOut->mFaces[iNum].mIndices[q] = iVertex;
							p_pcOut->mVertices[iVertex]		= (*avPositions)[(*avFaces)[*i].mIndices[q]];
							iVertex++;
						}
					}
				}
			}
			// add the mesh to the output list
			avOut->push_back(p_pcOut);
		}
	}
	delete[] aiSplit;
	return;
}
// ------------------------------------------------------------------------------------------------
void PLYImporter::ReplaceDefaultMaterial(std::vector<PLY::Face>* avFaces,
										 std::vector<MaterialHelper*>* avMaterials)
{
	bool bNeedDefaultMat = false;

	for (std::vector<PLY::Face>::iterator
		i =  avFaces->begin();i != avFaces->end();++i)
	{
		if (0xFFFFFFFF == (*i).iMaterialIndex)
		{
			bNeedDefaultMat = true;
			(*i).iMaterialIndex = avMaterials->size();
		}
		else if ((*i).iMaterialIndex >= avMaterials->size() )
		{
			// clamp the index
			(*i).iMaterialIndex = avMaterials->size()-1;
		}
	}

	if (bNeedDefaultMat)
	{
		// generate a default material
		MaterialHelper* pcHelper = new MaterialHelper();

		// fill in a default material
		int iMode = (int)aiShadingMode_Gouraud;
		pcHelper->AddProperty<int>(&iMode, 1, AI_MATKEY_SHADING_MODEL);

		aiColor3D clr;
		clr.b = clr.g = clr.r = 0.6f;
		pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_DIFFUSE);
		pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_SPECULAR);

		clr.b = clr.g = clr.r = 0.05f;
		pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_AMBIENT);

		avMaterials->push_back(pcHelper);
	}
	return;
}
// ------------------------------------------------------------------------------------------------
void PLYImporter::LoadVertices(std::vector<aiVector3D>* pvOut, bool p_bNormals)
{
	unsigned int aiPositions[3] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
	PLY::EDataType aiTypes[3];
	PLY::ElementInstanceList* pcList = NULL;
	unsigned int cnt = 0;

	// serach in the DOM for a vertex entry
	unsigned int _i = 0;
	for (std::vector<PLY::Element>::const_iterator
		i =  this->pcDOM->alElements.begin();
		i != this->pcDOM->alElements.end();++i,++_i)
	{
		if (PLY::EEST_Vertex == (*i).eSemantic)
		{
			pcList = &this->pcDOM->alElementData[_i];

			// load normal vectors?
			if (p_bNormals)
			{
				// now check whether which normal components are available
				unsigned int _a = 0;
				for (std::vector<PLY::Property>::const_iterator
					a =  (*i).alProperties.begin();
					a != (*i).alProperties.end();++a,++_a)
				{
					if ((*a).bIsList)continue;
					if (PLY::EST_XNormal == (*a).Semantic)
					{
						cnt++;
						aiPositions[0] = _a;
						aiTypes[0] = (*a).eType;
					}
					else if (PLY::EST_YNormal == (*a).Semantic)
					{
						cnt++;
						aiPositions[1] = _a;
						aiTypes[1] = (*a).eType;
					}
					else if (PLY::EST_ZNormal == (*a).Semantic)
					{
						cnt++;
						aiPositions[2] = _a;
						aiTypes[2] = (*a).eType;
					}
					if (3 == cnt)break; 
				}
			}
			// load vertex coordinates
			else
			{
				// now check whether which coordinate sets are available
				unsigned int _a = 0;
				for (std::vector<PLY::Property>::const_iterator
					a =  (*i).alProperties.begin();
					a != (*i).alProperties.end();++a,++_a)
				{
					if ((*a).bIsList)continue;
					if (PLY::EST_XCoord == (*a).Semantic)
					{
						cnt++;
						aiPositions[0] = _a;
						aiTypes[0] = (*a).eType;
					}
					else if (PLY::EST_YCoord == (*a).Semantic)
					{
						cnt++;
						aiPositions[1] = _a;
						aiTypes[1] = (*a).eType;
					}
					else if (PLY::EST_ZCoord == (*a).Semantic)
					{
						cnt++;
						aiPositions[2] = _a;
						aiTypes[2] = (*a).eType;
					}
					if (3 == cnt)break; 
				}
			}
			break;
		}
	}
	// check whether we have a valid source for the vertex data
	if (NULL != pcList && 0 != cnt)
	{
		pvOut->reserve(pcList->alInstances.size());
		for (std::vector<ElementInstance>::const_iterator
			i =  pcList->alInstances.begin();
			i != pcList->alInstances.end();++i)
		{
			// convert the vertices to sp floats
			aiVector3D vOut;

			if (0xFFFFFFFF == aiPositions[0])vOut.x = 0.0f;
			else
			{
				vOut.x = PLY::PropertyInstance::ConvertTo<float>(
					(*i).alProperties[aiPositions[0]].avList.front(),aiTypes[0]);
			}

			if (0xFFFFFFFF == aiPositions[1])vOut.y = 0.0f;
			else
			{
				vOut.y = PLY::PropertyInstance::ConvertTo<float>(
					(*i).alProperties[aiPositions[1]].avList.front(),aiTypes[1]);
			}

			if (0xFFFFFFFF == aiPositions[2])vOut.z = 0.0f;
			else
			{
				vOut.z = PLY::PropertyInstance::ConvertTo<float>(
					(*i).alProperties[aiPositions[2]].avList.front(),aiTypes[2]);
			}

			// and add them to our nice list
			pvOut->push_back(vOut);
		}
	}
	return;
}
// ------------------------------------------------------------------------------------------------
float NormalizeColorValue (PLY::PropertyInstance::ValueUnion val,PLY::EDataType eType)
{
	switch (eType)
	{
	case EDT_Float:
		return val.fFloat;
	case EDT_Double:
		return (float)val.fDouble;

	case EDT_UChar:
		return (float)val.iUInt / (float)0xFF;
	case EDT_Char:
		return (float)(val.iInt+(0xFF/2)) / (float)0xFF;
	case EDT_UShort:
		return (float)val.iUInt / (float)0xFFFF;
	case EDT_Short:
		return (float)(val.iInt+(0xFFFF/2)) / (float)0xFFFF;
	case EDT_UInt:
		return (float)val.iUInt / (float)0xFFFF;
	case EDT_Int:
		return ((float)val.iInt / (float)0xFF) + 0.5f;
	};
	return 0.0f;
}
// ------------------------------------------------------------------------------------------------
void PLYImporter::LoadVertexColor(std::vector<aiColor4D>* pvOut)
{
	unsigned int aiPositions[4] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
	PLY::EDataType aiTypes[4];
	unsigned int cnt = 0;
	PLY::ElementInstanceList* pcList = NULL;

	// serach in the DOM for a vertex entry
	unsigned int _i = 0;
	for (std::vector<PLY::Element>::const_iterator
		i =  this->pcDOM->alElements.begin();
		i != this->pcDOM->alElements.end();++i,++_i)
	{
		if (PLY::EEST_Vertex == (*i).eSemantic)
		{
			pcList = &this->pcDOM->alElementData[_i];

			// now check whether which coordinate sets are available
			unsigned int _a = 0;
			for (std::vector<PLY::Property>::const_iterator
				a =  (*i).alProperties.begin();
				a != (*i).alProperties.end();++a,++_a)
			{
				if ((*a).bIsList)continue;
				if (PLY::EST_Red == (*a).Semantic)
				{
					cnt++;
					aiPositions[0] = _a;
					aiTypes[0] = (*a).eType;
				}
				else if (PLY::EST_Green == (*a).Semantic)
				{
					cnt++;
					aiPositions[1] = _a;
					aiTypes[1] = (*a).eType;
				}
				else if (PLY::EST_Blue == (*a).Semantic)
				{
					cnt++;
					aiPositions[2] = _a;
					aiTypes[2] = (*a).eType;
				}
				else if (PLY::EST_Alpha == (*a).Semantic)
				{
					cnt++;
					aiPositions[3] = _a;
					aiTypes[3] = (*a).eType;
				}
				if (4 == cnt)break; 
			}
			break;
		}
	}
	// check whether we have a valid source for the vertex data
	if (NULL != pcList && 0 != cnt)
	{
		pvOut->reserve(pcList->alInstances.size());
		for (std::vector<ElementInstance>::const_iterator
			i =  pcList->alInstances.begin();
			i != pcList->alInstances.end();++i)
		{
			// convert the vertices to sp floats
			aiColor4D vOut;
			
			if (0xFFFFFFFF == aiPositions[0])vOut.r = 0.0f;
			else
			{
				vOut.r = NormalizeColorValue((*i).alProperties[
					aiPositions[0]].avList.front(),aiTypes[0]);
			}

			if (0xFFFFFFFF == aiPositions[1])vOut.g = 0.0f;
			else
			{
				vOut.g = NormalizeColorValue((*i).alProperties[
					aiPositions[1]].avList.front(),aiTypes[1]);
			}

			if (0xFFFFFFFF == aiPositions[2])vOut.b = 0.0f;
			else
			{
				vOut.b = NormalizeColorValue((*i).alProperties[
					aiPositions[2]].avList.front(),aiTypes[2]);
			}

			// assume 1.0 for the alpha channel ifit is not set
			if (0xFFFFFFFF == aiPositions[3])vOut.a = 1.0f;
			else
			{
				vOut.a = NormalizeColorValue((*i).alProperties[
					aiPositions[3]].avList.front(),aiTypes[3]);
			}

			// and add them to our nice list
			pvOut->push_back(vOut);
		}
	}
	return;
}

// ------------------------------------------------------------------------------------------------
void PLYImporter::LoadFaces(std::vector<PLY::Face>* pvOut)
{
	PLY::ElementInstanceList* pcList = NULL;
	bool bOne = false;

	// index of the vertex index list
	unsigned int iProperty = 0xFFFFFFFF;
	PLY::EDataType eType;
	bool bIsTristrip = false;

	// index of the material index property
	unsigned int iMaterialIndex = 0xFFFFFFFF;
	PLY::EDataType eType2;

	// serach in the DOM for a face entry
	unsigned int _i = 0;
	for (std::vector<PLY::Element>::const_iterator 
		i =  this->pcDOM->alElements.begin();
		i != this->pcDOM->alElements.end();++i,++_i)
	{
		// face = unique number of vertex indices
		if (PLY::EEST_Face == (*i).eSemantic)
		{
			pcList = &this->pcDOM->alElementData[_i];
			unsigned int _a = 0;
			for (std::vector<PLY::Property>::const_iterator 
				a =  (*i).alProperties.begin();
				a != (*i).alProperties.end();++a,++_a)
			{
				if (PLY::EST_VertexIndex == (*a).Semantic)
				{
					// must be a dynamic list!
					if (!(*a).bIsList)continue;
					iProperty	= _a;
					bOne		= true;
					eType		= (*a).eType;		
				}
				else if (PLY::EST_MaterialIndex == (*a).Semantic)
				{
					if ((*a).bIsList)continue;
					iMaterialIndex	= _a;
					bOne			= true;
					eType2		= (*a).eType;		
				}
			}
			break;
		}
		// triangle strip
		// TODO: triangle strip and material index support???
		else if (PLY::EEST_TriStrip == (*i).eSemantic)
		{
			// find a list property in this ...
			pcList = &this->pcDOM->alElementData[_i];
			unsigned int _a = 0;
			for (std::vector<PLY::Property>::const_iterator 
				a =  (*i).alProperties.begin();
				a != (*i).alProperties.end();++a,++_a)
			{
				// must be a dynamic list!
				if (!(*a).bIsList)continue;
				iProperty	= _a;
				bOne		= true;
				bIsTristrip	= true;
				eType		= (*a).eType;	
				break;
			}
			break;
		}
	}
	// check whether we have at least one per-face information set
	if (pcList && bOne)
	{
		if (!bIsTristrip)
		{
			pvOut->reserve(pcList->alInstances.size());
			for (std::vector<ElementInstance>::const_iterator 
				i =  pcList->alInstances.begin();
				i != pcList->alInstances.end();++i)
			{
				PLY::Face sFace;

				// parse the list of vertex indices
				if (0xFFFFFFFF != iProperty)
				{
					const unsigned int iNum = (*i).alProperties[iProperty].avList.size();
					sFace.mIndices.resize(iNum);

					std::list<PLY::PropertyInstance::ValueUnion>::const_iterator p = 
						(*i).alProperties[iProperty].avList.begin();

					for (unsigned int a = 0; a < iNum;++a,++p)
					{
						sFace.mIndices[a] = PLY::PropertyInstance::ConvertTo<unsigned int>(*p,eType);
					}
				}

				// parse the material index
				if (0xFFFFFFFF != iMaterialIndex)
				{
					sFace.iMaterialIndex = PLY::PropertyInstance::ConvertTo<unsigned int>(
						(*i).alProperties[iMaterialIndex].avList.front(),eType2);
				}
				pvOut->push_back(sFace);
			}
		}
		else // triangle strips
		{
			// normally we have only one triangle strip instance where
			// a value of -1 indicates a restart of the strip
			for (std::vector<ElementInstance>::const_iterator
				i =  pcList->alInstances.begin();
				i != pcList->alInstances.end();++i)
			{
				int aiTable[2] = {-1,-1};
				for (std::list<PLY::PropertyInstance::ValueUnion>::const_iterator 
					a =  (*i).alProperties[iProperty].avList.begin();
					a != (*i).alProperties[iProperty].avList.end();++a)
				{
					int p = PLY::PropertyInstance::ConvertTo<int>(*a,eType);
					if (-1 == p)
					{
						// restart the strip ...
						aiTable[0] = aiTable[1] = -1;
						continue;
					}
					if (-1 == aiTable[0])
					{
						aiTable[0] = p;
						continue;
					}
					if (-1 == aiTable[1])
					{
						aiTable[1] = p;
						continue;
					}
				
					PLY::Face sFace;
					sFace.mIndices.push_back((unsigned int)aiTable[0]);
					sFace.mIndices.push_back((unsigned int)aiTable[1]);
					sFace.mIndices.push_back((unsigned int)p);
					pvOut->push_back(sFace);

					aiTable[0] = aiTable[1];
					aiTable[1] = p;
				}
			}
		}
	}
	return;
}
// ------------------------------------------------------------------------------------------------
void GetMaterialColor(const std::vector<PLY::PropertyInstance>& avList,
					  unsigned int aiPositions[4], 
					  PLY::EDataType aiTypes[4],
					  aiColor4D* clrOut)
{
	ai_assert(NULL != clrOut);

	if (0xFFFFFFFF == aiPositions[0])clrOut->r = 0.0f;
	else
	{
		clrOut->r = NormalizeColorValue(avList[
			aiPositions[0]].avList.front(),aiTypes[0]);
	}

	if (0xFFFFFFFF == aiPositions[1])clrOut->g = 0.0f;
	else
	{
		clrOut->g = NormalizeColorValue(avList[
			aiPositions[1]].avList.front(),aiTypes[1]);
	}

	if (0xFFFFFFFF == aiPositions[2])clrOut->b = 0.0f;
	else
	{
		clrOut->b = NormalizeColorValue(avList[
			aiPositions[2]].avList.front(),aiTypes[2]);
	}

	// assume 1.0 for the alpha channel ifit is not set
	if (0xFFFFFFFF == aiPositions[3])clrOut->a = 1.0f;
	else
	{
		clrOut->a = NormalizeColorValue(avList[
			aiPositions[3]].avList.front(),aiTypes[3]);
	}

	return;
}
// ------------------------------------------------------------------------------------------------
void PLYImporter::LoadMaterial(std::vector<MaterialHelper*>* pvOut)
{
	// diffuse[4], specular[4], ambient[4]
	// rgba order
	unsigned int aaiPositions[3][4] = {

		{0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
		{0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
		{0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
	};

	// dto.
	PLY::EDataType aaiTypes[3][4];
	PLY::ElementInstanceList* pcList = NULL;

	unsigned int iPhong = 0xFFFFFFFF;
	PLY::EDataType ePhong;

	unsigned int iOpacity = 0xFFFFFFFF;
	PLY::EDataType eOpacity;

	// serach in the DOM for a vertex entry
	unsigned int _i = 0;
	for (std::vector<PLY::Element>::const_iterator
		i =  this->pcDOM->alElements.begin();
		i != this->pcDOM->alElements.end();++i,++_i)
	{
		if (PLY::EEST_Material == (*i).eSemantic)
		{
			pcList = &this->pcDOM->alElementData[_i];

			// now check whether which coordinate sets are available
			unsigned int _a = 0;
			for (std::vector<PLY::Property>::const_iterator
				a =  (*i).alProperties.begin();
				a != (*i).alProperties.end();++a,++_a)
			{
				if ((*a).bIsList)continue;

				// pohng specularity      -----------------------------------
				if (PLY::EST_PhongPower == (*a).Semantic)
				{
					iPhong		= _a;
					ePhong		= (*a).eType;
				}

				// general opacity        -----------------------------------
				if (PLY::EST_Opacity == (*a).Semantic)
				{
					iOpacity		= _a;
					eOpacity		= (*a).eType;
				}

				// diffuse color channels -----------------------------------
				if (PLY::EST_DiffuseRed == (*a).Semantic)
				{
					aaiPositions[0][0]	= _a;
					aaiTypes[0][0]		= (*a).eType;
				}
				else if (PLY::EST_DiffuseGreen == (*a).Semantic)
				{
					aaiPositions[0][1]	= _a;
					aaiTypes[0][1]		= (*a).eType;
				}
				else if (PLY::EST_DiffuseBlue == (*a).Semantic)
				{
					aaiPositions[0][2]	= _a;
					aaiTypes[0][2]		= (*a).eType;
				}
				else if (PLY::EST_DiffuseAlpha == (*a).Semantic)
				{
					aaiPositions[0][3]	= _a;
					aaiTypes[0][3]		= (*a).eType;
				}
				// specular color channels -----------------------------------
				else if (PLY::EST_SpecularRed == (*a).Semantic)
				{
					aaiPositions[1][0]	= _a;
					aaiTypes[1][0]		= (*a).eType;
				}
				else if (PLY::EST_SpecularGreen == (*a).Semantic)
				{
					aaiPositions[1][1]	= _a;
					aaiTypes[1][1]		= (*a).eType;
				}
				else if (PLY::EST_SpecularBlue == (*a).Semantic)
				{
					aaiPositions[1][2]	= _a;
					aaiTypes[1][2]		= (*a).eType;
				}
				else if (PLY::EST_SpecularAlpha == (*a).Semantic)
				{
					aaiPositions[1][3]	= _a;
					aaiTypes[1][3]		= (*a).eType;
				}
				// ambient color channels -----------------------------------
				else if (PLY::EST_AmbientRed == (*a).Semantic)
				{
					aaiPositions[2][0]	= _a;
					aaiTypes[2][0]		= (*a).eType;
				}
				else if (PLY::EST_AmbientGreen == (*a).Semantic)
				{
					aaiPositions[2][1]	= _a;
					aaiTypes[2][1]		= (*a).eType;
				}
				else if (PLY::EST_AmbientBlue == (*a).Semantic)
				{
					aaiPositions[22][2]	= _a;
					aaiTypes[2][2]		= (*a).eType;
				}
				else if (PLY::EST_AmbientAlpha == (*a).Semantic)
				{
					aaiPositions[2][3]	= _a;
					aaiTypes[2][3]		= (*a).eType;
				}
			}
			break;
		}
	}
	// check whether we have a valid source for the material data
	if (NULL != pcList)
	{
		for (std::vector<ElementInstance>::const_iterator
			i =  pcList->alInstances.begin();
			i != pcList->alInstances.end();++i)
		{
			aiColor4D clrOut;
			MaterialHelper* pcHelper = new MaterialHelper();
	
			// build the diffuse material color
			GetMaterialColor((*i).alProperties,aaiPositions[0],aaiTypes[0],&clrOut);
			pcHelper->AddProperty<aiColor4D>(&clrOut,1,AI_MATKEY_COLOR_DIFFUSE);

			// build the specular material color
			GetMaterialColor((*i).alProperties,aaiPositions[1],aaiTypes[1],&clrOut);
			pcHelper->AddProperty<aiColor4D>(&clrOut,1,AI_MATKEY_COLOR_SPECULAR);

			// build the ambient material color
			GetMaterialColor((*i).alProperties,aaiPositions[2],aaiTypes[2],&clrOut);
			pcHelper->AddProperty<aiColor4D>(&clrOut,1,AI_MATKEY_COLOR_AMBIENT);

			// handle phong power and shading mode
			int iMode;
			if (0xFFFFFFFF != iPhong)
			{
				float fSpec = PLY::PropertyInstance::ConvertTo<float>(
					(*i).alProperties[iPhong].avList.front(),ePhong);

				// if shininess is 0 (and the pow() calculation would therefore always
				// become 1, not depending on the angle) use gouraud lighting
				if (0.0f != fSpec)
				{

					// scale this with 15 ... hopefully this is correct
					fSpec += 15;

					pcHelper->AddProperty<float>(&fSpec, 1, AI_MATKEY_SHININESS);

					iMode = (int)aiShadingMode_Phong;
				}
				else iMode = (int)aiShadingMode_Gouraud;
			}
			else iMode = (int)aiShadingMode_Gouraud;
			pcHelper->AddProperty<int>(&iMode, 1, AI_MATKEY_SHADING_MODEL);

			// handle opacity
			if (0xFFFFFFFF != iOpacity)
			{
				float fOpacity = PLY::PropertyInstance::ConvertTo<float>(
					(*i).alProperties[iPhong].avList.front(),eOpacity);

				pcHelper->AddProperty<float>(&fOpacity, 1, AI_MATKEY_OPACITY);
			}

			// add the newly created material instance to the list
			pvOut->push_back(pcHelper);
		}
	}
	return;
}