assimp.assimp/code/IFCLoader.cpp

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

Copyright (c) 2006-2010, ASSIMP Development Team
All rights reserved.

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  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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*/

/** @file  IFC.cpp
 *  @brief Implementation of the Industry Foundation Classes loader 
 */
#include "AssimpPCH.h"

#ifndef ASSIMP_BUILD_NO_IFC_IMPORTER

#include "IFCLoader.h"
#include "STEPFileReader.h"
#include "IFCReaderGen.h"

#include "StreamReader.h"
#include "MemoryIOWrapper.h"
#include "ProcessHelper.h"

#include <boost/tuple/tuple.hpp>

using namespace Assimp;
using namespace Assimp::Formatter;
namespace EXPRESS = STEP::EXPRESS;

const std::string LogFunctions<IFCImporter>::log_prefix = "IFC: ";


/* DO NOT REMOVE this comment block. The genentitylist.sh script
 * just looks for names adhering to the IFC :: IfcSomething naming scheme
 * and includes all matches in the whitelist for code-generation. Thus,
 * all entity classes that are only indirectly referenced need to be
 * mentioned explicitly.

  IFC::IfcRepresentationMap
  IFC::IfcProductRepresentation
  IFC::IfcUnitAssignment
  IFC::IfcClosedShell
  IFC::IfcDoor

 */

namespace {

	// helper for std::for_each to delete all heap-allocated items in a container
template<typename T>
struct delete_fun
{
	void operator()(T* del) {
		delete del;
	}
};


	// intermediate data dump during conversion
struct ConversionData 
{
	ConversionData(const STEP::DB& db, const IFC::IfcProject& proj, aiScene* out,const IFCImporter::Settings& settings)
		: len_scale(1.0)
		, db(db)
		, proj(proj)
		, out(out)
		, settings(settings)
	{}

	~ConversionData() {
		std::for_each(meshes.begin(),meshes.end(),delete_fun<aiMesh>());
		std::for_each(materials.begin(),materials.end(),delete_fun<aiMaterial>());
	}

	float len_scale;

	const STEP::DB& db;
	const IFC::IfcProject& proj;
	aiScene* out;

	aiMatrix4x4 wcs;
	std::vector<aiMesh*> meshes;
	std::vector<aiMaterial*> materials;

	typedef std::map<const IFC::IfcRepresentationItem*, std::vector<unsigned int> > MeshCache;
	MeshCache cached_meshes;

	const IFCImporter::Settings& settings;
};

	// helper used during mesh construction
struct TempMesh
{
	std::vector<aiVector3D> verts;
	std::vector<unsigned int> vertcnt;
	std::vector<unsigned int> mat_idx;

	aiMesh* ToMesh() {
		ai_assert(verts.size() == std::accumulate(vertcnt.begin(),vertcnt.end(),0));

		if (verts.empty()) {
			return NULL;
		}

		std::auto_ptr<aiMesh> mesh(new aiMesh());

		// copy vertices
		mesh->mNumVertices = static_cast<unsigned int>(verts.size());
		mesh->mVertices = new aiVector3D[mesh->mNumVertices];
		std::copy(verts.begin(),verts.end(),mesh->mVertices);

		// and build up faces
		mesh->mNumFaces = static_cast<unsigned int>(vertcnt.size());
		mesh->mFaces = new aiFace[mesh->mNumFaces];

		for(unsigned int i = 0, acc = 0; i < mesh->mNumFaces; ++i) {
			aiFace& f = mesh->mFaces[i];

			f.mNumIndices = vertcnt[i];
			f.mIndices = new unsigned int[f.mNumIndices];
			for(unsigned int a = 0; a < f.mNumIndices; ++a) {
				f.mIndices[a] = acc++;
			}
		}

		// XXX materials
		mesh->mMaterialIndex = UINT_MAX;
		return mesh.release();
	}
};



// forward declarations
float ConvertSIPrefix(const std::string& prefix);
void SetUnits(ConversionData& conv);
void ConvertAxisPlacement(aiMatrix4x4& out, const IFC::IfcAxis2Placement& in, ConversionData& conv);
void SetCoordinateSpace(ConversionData& conv);
void ProcessSpatialStructures(ConversionData& conv);
aiNode* ProcessSpatialStructure(aiNode* parent, const IFC::IfcProduct& el ,ConversionData& conv);
void ProcessProductRepresentation(const IFC::IfcProduct& el, aiNode* nd, ConversionData& conv);
void MakeTreeRelative(ConversionData& conv);

} // anon

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

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

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file. 
bool IFCImporter::CanRead( const std::string& pFile, IOSystem* pIOHandler, bool checkSig) const
{
	const std::string& extension = GetExtension(pFile);
	if (extension == "ifc") {
		return true;
	}

	else if ((!extension.length() || checkSig) && pIOHandler)	{
		// note: this is the common identification for STEP-encoded files, so
		// it is only unambiguous as long as we don't support any further
		// file formats with STEP as their encoding.
		const char* tokens[] = {"ISO-10303-21"};
		return SearchFileHeaderForToken(pIOHandler,pFile,tokens,1);
	}
	return false;
}

// ------------------------------------------------------------------------------------------------
// List all extensions handled by this loader
void IFCImporter::GetExtensionList(std::set<std::string>& app) 
{
	app.insert("ifc");
}


// ------------------------------------------------------------------------------------------------
// Setup configuration properties for the loader
void IFCImporter::SetupProperties(const Importer* pImp)
{
	settings.skipSpaceRepresentations = pImp->GetPropertyBool(AI_CONFIG_IMPORT_IFC_SKIP_SPACE_REPRESENTATIONS,true);
	settings.skipCurveRepresentations = pImp->GetPropertyBool(AI_CONFIG_IMPORT_IFC_SKIP_CURVE_REPRESENTATIONS,false);
}


// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure. 
void IFCImporter::InternReadFile( const std::string& pFile, 
	aiScene* pScene, IOSystem* pIOHandler)
{
	boost::shared_ptr<IOStream> stream(pIOHandler->Open(pFile));
	if (!stream) {
		ThrowException("Could not open file for reading");
	}

	boost::scoped_ptr<STEP::DB> db(STEP::ReadFileHeader(stream));
	const STEP::HeaderInfo& head = const_cast<const STEP::DB&>(*db).GetHeader();

	if(!head.fileSchema.size() || head.fileSchema.substr(0,3) != "IFC") {
		ThrowException("Unrecognized file schema: " + head.fileSchema);
	}

	if (!DefaultLogger::isNullLogger()) {
		LogDebug("File schema is \'" + head.fileSchema + '\'');
		if (head.timestamp.length()) {
			LogDebug("Timestamp \'" + head.timestamp + '\'');
		}
		if (head.app.length()) {
			LogDebug("Application/Exporter identline is \'" + head.app  + '\'');
		}
	}

	// obtain a copy of the machine-generated IFC scheme
	EXPRESS::ConversionSchema schema;
	IFC::GetSchema(schema);

	// feed the IFC schema into the reader and pre-parse all lines
	STEP::ReadFile(*db, schema);

	const STEP::LazyObject* proj =  db->GetObject("ifcproject");
	if (!proj) {
		ThrowException("missing IfcProject entity");
	}

	ConversionData conv(*db,proj->To<IFC::IfcProject>(),pScene,settings);
	SetUnits(conv);
	SetCoordinateSpace(conv);
	ProcessSpatialStructures(conv);
	MakeTreeRelative(conv);

#ifdef ASSIMP_IFC_TEST
	db->EvaluateAll();
#endif

	// do final data copying
	if (conv.meshes.size()) {
		pScene->mNumMeshes = static_cast<unsigned int>(conv.meshes.size());
		pScene->mMeshes = new aiMesh*[pScene->mNumMeshes]();
		std::copy(conv.meshes.begin(),conv.meshes.end(),pScene->mMeshes);

		// needed to keep the d'tor from burning us
		conv.meshes.clear();
	}

	if (conv.materials.size()) {
		pScene->mNumMaterials = static_cast<unsigned int>(conv.materials.size());
		pScene->mMaterials = new aiMaterial*[pScene->mNumMaterials]();
		std::copy(conv.materials.begin(),conv.materials.end(),pScene->mMaterials);

		// needed to keep the d'tor from burning us
		conv.materials.clear();
	}

	// apply world coordinate system (which includes the scaling to convert to meters and a -90 degrees rotation around x)
	aiMatrix4x4 scale, rot;
	aiMatrix4x4::Scaling(aiVector3D(conv.len_scale,conv.len_scale,conv.len_scale),scale);
	aiMatrix4x4::RotationX(-AI_MATH_HALF_PI_F,rot);

	pScene->mRootNode->mTransformation = rot * scale * conv.wcs * pScene->mRootNode->mTransformation;

	// this must be last because objects are evaluated lazily as we process them
	if ( !DefaultLogger::isNullLogger() ){
		LogDebug((Formatter::format(),"STEP: evaluated ",db->GetEvaluatedObjectCount()," object records"));
	}
}

namespace {

// ------------------------------------------------------------------------------------------------
bool IsTrue(const EXPRESS::BOOLEAN& in)
{
	return (std::string)in == "TRUE" || (std::string)in == "T";
}

// ------------------------------------------------------------------------------------------------
float ConvertSIPrefix(const std::string& prefix)
{
	if (prefix == "EXA") {
		return 1e18f;
	}
	else if (prefix == "PETA") {
		return 1e15f;
	}
	else if (prefix == "TERA") {
		return 1e12f;
	}
	else if (prefix == "GIGA") {
		return 1e9f;
	}
	else if (prefix == "MEGA") {
		return 1e6f;
	}
	else if (prefix == "KILO") {
		return 1e3f;
	}
	else if (prefix == "HECTO") {
		return 1e2f;
	}
	else if (prefix == "DECA") {
		return 1e-0f;
	}
	else if (prefix == "DECI") {
		return 1e-1f;
	}
	else if (prefix == "CENTI") {
		return 1e-2f;
	}
	else if (prefix == "MILLI") {
		return 1e-3f;
	}
	else if (prefix == "MICRO") {
		return 1e-6f;
	}
	else if (prefix == "NANO") {
		return 1e-9f;
	}
	else if (prefix == "PICO") {
		return 1e-12f;
	}
	else if (prefix == "FEMTO") {
		return 1e-15f;
	}
	else if (prefix == "ATTO") {
		return 1e-18f;
	}
	else {
		IFCImporter::LogError("Unrecognized SI prefix: " + prefix);
		return 1;
	}
}

// ------------------------------------------------------------------------------------------------
void SetUnits(ConversionData& conv)
{
	// see if we can determine the coordinate space used to express
	for(size_t i = 0; i <  conv.proj.UnitsInContext->Units.size(); ++i ) {
		try {
			const EXPRESS::ENTITY& e = conv.proj.UnitsInContext->Units[i]->To<IFC::ENTITY>();
			const IFC::IfcSIUnit& si = conv.db.MustGetObject(e).To<IFC::IfcSIUnit>(); 

			if(si.UnitType == "LENGTHUNIT" && si.Prefix) {
				conv.len_scale = ConvertSIPrefix(si.Prefix);
				IFCImporter::LogDebug("got units used for lengths");
			}
		}
		catch(std::bad_cast&) {
			// not SI unit, not implemented
			continue;
		}
	}

}

// ------------------------------------------------------------------------------------------------
void ConvertColor(aiColor4D& out, const IFC::IfcColourRgb& in)
{
	out.r = in.Red;
	out.g = in.Green;
	out.b = in.Blue;
	out.a = 1.f;
}

// ------------------------------------------------------------------------------------------------
void ConvertColor(aiColor4D& out, const IFC::IfcColourOrFactor* in,ConversionData& conv,const aiColor4D* base)
{
	if (const EXPRESS::REAL* const r = in->ToPtr<EXPRESS::REAL>()) {
		out.r = out.g = out.b = *r;
		if(base) {
			out.r *= base->r;
			out.g *= base->g;
			out.b *= base->b;
			out.a = base->a;
		}
		else out.a = 1.0;
	}
	else if (const IFC::IfcColourRgb* const rgb = in->ResolveSelectPtr<IFC::IfcColourRgb>(conv.db)) {
		ConvertColor(out,*rgb);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcColourOrFactor entity");
	}
}

// ------------------------------------------------------------------------------------------------
void ConvertCartesianPoint(aiVector3D& out, const IFC::IfcCartesianPoint& in)
{
	out = aiVector3D();
	for(size_t i = 0; i < in.Coordinates.size(); ++i) {
		out[i] = in.Coordinates[i];
	}
}

// ------------------------------------------------------------------------------------------------
void ConvertDirection(aiVector3D& out, const IFC::IfcDirection& in)
{
	out = aiVector3D();
	for(size_t i = 0; i < in.DirectionRatios.size(); ++i) {
		out[i] = in.DirectionRatios[i];
	}
	const float len = out.Length();
	if (len<1e-6) {
		IFCImporter::LogWarn("direction vector too small, normalizing would result in a division by zero");
		return;
	}
	out /= len;
}

// ------------------------------------------------------------------------------------------------
void AssignMatrixAxes(aiMatrix4x4& out, const aiVector3D& x, const aiVector3D& y, const aiVector3D& z)
{
	out.a1 = x.x;
	out.b1 = x.y;
	out.c1 = x.z;

	out.a2 = y.x;
	out.b2 = y.y;
	out.c2 = y.z;

	out.a3 = z.x;
	out.b3 = z.y;
	out.c3 = z.z;
}

// ------------------------------------------------------------------------------------------------
void ConvertAxisPlacement(aiMatrix4x4& out, const IFC::IfcAxis2Placement3D& in, ConversionData& conv)
{
	aiVector3D loc;
	ConvertCartesianPoint(loc,in.Location);

	aiVector3D z(0.f,0.f,1.f),r(0.f,1.f,0.f),x;

	if (in.Axis) { 
		ConvertDirection(z,*in.Axis.Get());
	}
	if (in.RefDirection) {
		ConvertDirection(r,*in.RefDirection.Get());
	}

	aiVector3D v = r.Normalize();
	aiVector3D tmpx = z * (v*z);

	x = (v-tmpx).Normalize();
	aiVector3D y = (z^x);

	aiMatrix4x4::Translation(loc,out);
	AssignMatrixAxes(out,x,y,z);
}

// ------------------------------------------------------------------------------------------------
void ConvertAxisPlacement(aiMatrix4x4& out, const IFC::IfcAxis2Placement2D& in, ConversionData& conv)
{
	aiVector3D loc;
	ConvertCartesianPoint(loc,in.Location);

	aiVector3D x(1.f,0.f,1.f);
	if (in.RefDirection) {
		ConvertDirection(x,*in.RefDirection.Get());
	}

	const aiVector3D y = aiVector3D(x.y,-x.x,0.f);

	aiMatrix4x4::Translation(loc,out);
	AssignMatrixAxes(out,x,y,aiVector3D(0.f,0.f,1.f));
}

// ------------------------------------------------------------------------------------------------
void ConvertAxisPlacement(aiMatrix4x4& out, const IFC::IfcAxis2Placement& in, ConversionData& conv)
{
	if(const IFC::IfcAxis2Placement3D* pl3 = in.ResolveSelectPtr<IFC::IfcAxis2Placement3D>(conv.db)) {
		ConvertAxisPlacement(out,*pl3,conv);
	}
	else if(const IFC::IfcAxis2Placement2D* pl2 = in.ResolveSelectPtr<IFC::IfcAxis2Placement2D>(conv.db)) {
		ConvertAxisPlacement(out,*pl2,conv);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcAxis2Placement entity");
	}
}

// ------------------------------------------------------------------------------------------------
void SetCoordinateSpace(ConversionData& conv)
{
	const IFC::IfcRepresentationContext* fav = NULL;
	BOOST_FOREACH(const IFC::IfcRepresentationContext& v, conv.proj.RepresentationContexts) {
		fav = &v;
		// Model should be the most suitable type of context, hence ignore the others 
		if (v.ContextType && v.ContextType.Get() == "Model") { 
			break;
		}
	}
	if (fav) {
		if(const IFC::IfcGeometricRepresentationContext* const geo = fav->ToPtr<IFC::IfcGeometricRepresentationContext>()) {
			ConvertAxisPlacement(conv.wcs, *geo->WorldCoordinateSystem, conv);
			IFCImporter::LogDebug("got world coordinate system");
		}
	}
}

// ------------------------------------------------------------------------------------------------
void ConvertTransformOperator(aiMatrix4x4& out, const IFC::IfcCartesianTransformationOperator& op)
{
	aiVector3D loc;
	ConvertCartesianPoint(loc,op.LocalOrigin);

	aiVector3D x(1.f,0.f,0.f),y(0.f,1.f,0.f),z(0.f,0.f,1.f);
	if (op.Axis1) {
		ConvertDirection(x,*op.Axis1.Get());
	}
	if (op.Axis2) {
		ConvertDirection(y,*op.Axis2.Get());
	}
	if (const IFC::IfcCartesianTransformationOperator3D* op2 = op.ToPtr<IFC::IfcCartesianTransformationOperator3D>()) {
		if(op2->Axis3) {
			ConvertDirection(z,*op2->Axis3.Get());
		}
	}

	aiMatrix4x4 locm;
	aiMatrix4x4::Translation(loc,locm);	
	AssignMatrixAxes(out,x,y,z);

	const float sc = op.Scale?op.Scale.Get():1.f;

	aiMatrix4x4 s;
	aiMatrix4x4::Scaling(aiVector3D(sc,sc,sc),s);

	out = locm * out * s;
}

// ------------------------------------------------------------------------------------------------
bool ProcessPolyloop(const IFC::IfcPolyLoop& loop, TempMesh& meshout, ConversionData& conv)
{
	size_t cnt = 0;
	BOOST_FOREACH(const IFC::IfcCartesianPoint& c, loop.Polygon) {
		aiVector3D tmp;
		ConvertCartesianPoint(tmp,c);

		meshout.verts.push_back(tmp);
		++cnt;
	}
	// zero- or one- vertex polyloops simply ignored
	if (cnt >= 1) { 
		meshout.vertcnt.push_back(cnt);
		return true;
	}
	
	if (cnt==1) {
		meshout.vertcnt.pop_back();
	}
	return false;
}

// ------------------------------------------------------------------------------------------------
void ProcessConnectedFaceSet(const IFC::IfcConnectedFaceSet& fset, TempMesh& result, ConversionData& conv)
{
	BOOST_FOREACH(const IFC::IfcFace& face, fset.CfsFaces) {
		TempMesh meshout;

		size_t ob = face.Bounds.size(), cnt = 0;
		BOOST_FOREACH(const IFC::IfcFaceBound& bound, face.Bounds) {
			
			if(const IFC::IfcPolyLoop* const polyloop = bound.Bound->ToPtr<IFC::IfcPolyLoop>()) {
				if(ProcessPolyloop(*polyloop, meshout, conv)) {
					if(bound.ToPtr<IFC::IfcFaceOuterBound>()) {
						ob = cnt;
					}
					++cnt;
				}
			}
			else {
				IFCImporter::LogWarn("skipping unknown IfcFaceBound entity, type is " + bound.Bound->GetClassName());
				continue;
			}

			if(!IsTrue(bound.Orientation)) {
				size_t c = 0;
				BOOST_FOREACH(unsigned int& i, meshout.vertcnt) {
					std::reverse(meshout.verts.begin() + cnt,meshout.verts.begin() + cnt + c);
					cnt += c;
				}
			}
			
		}

		result.vertcnt.reserve(meshout.vertcnt.size()+result.vertcnt.size());
		if (meshout.vertcnt.size() <= 1) {
			result.verts.reserve(meshout.verts.size()+result.verts.size());

			std::copy(meshout.verts.begin(),meshout.verts.end(),std::back_inserter(result.verts));
			std::copy(meshout.vertcnt.begin(),meshout.vertcnt.end(),std::back_inserter(result.vertcnt));
			continue;
		}

		IFCImporter::LogDebug("fixing polygon with holes for triangulation via ear-cutting");

		// each hole results in two extra vertices
		result.verts.reserve(meshout.verts.size()+cnt*2+result.verts.size());

		// handle polygons with holes. our built in triangulation won't handle them as is, but
		// the ear cutting algorithm is solid enough to deal with them if we join the inner
		// holes with the outer boundaries by dummy connections.
		size_t outer_polygon_start = 0;
		
		// see if one of the polygons is a IfcFaceOuterBound - treats this as the outer boundary.
		// sadly we can't rely on it, the docs say 'At most one of the bounds shall be of the type IfcFaceOuterBound' 
		std::vector<unsigned int>::iterator outer_polygon = meshout.vertcnt.end(), begin=meshout.vertcnt.begin(),  iit;
		if (ob < face.Bounds.size()) {
			outer_polygon = begin + ob;
			outer_polygon_start = std::accumulate(begin,outer_polygon,0);
		}
		else {
			float area_outer_polygon = 1e-10f;

			// find the polygon with the largest area, it must be the outer bound. 
			size_t max_vcount = 0;
			for(iit = begin; iit != meshout.vertcnt.end(); ++iit) {
				ai_assert(*iit);
				max_vcount = std::max(max_vcount,static_cast<size_t>(*iit));
			}
			std::vector<float> temp((max_vcount+2)*4);
			size_t vidx = 0;
			for(iit = begin; iit != meshout.vertcnt.end(); vidx += *iit++) {

				for(size_t vofs = 0, cnt = 0; vofs < *iit; ++vofs) {
					const aiVector3D& v = meshout.verts[vidx+vofs];
					temp[cnt++] = v.x;
					temp[cnt++] = v.y;
					temp[cnt++] = v.z;
#ifdef _DEBUG
					temp[cnt] = std::numeric_limits<float>::quiet_NaN();
#endif
					++cnt;
				}
				
				aiVector3D nor;
				NewellNormal<4,4,4>(nor,*iit,&temp[0],&temp[1],&temp[2]);
				const float area = nor.SquareLength();

				if (area > area_outer_polygon) {
					area_outer_polygon = area;
					outer_polygon = iit;
					outer_polygon_start = vidx;
				}
			}
		}

		ai_assert(outer_polygon != meshout.vertcnt.end());	

		typedef boost::tuple<unsigned int, unsigned int, unsigned int> InsertionPoint;
		std::vector< InsertionPoint > insertions(*outer_polygon,boost::make_tuple(0u,0u,0u));

		// iterate through all other polyloops and find points in the outer polyloop that are close
		size_t vidx = 0;
		for(iit = begin; iit != meshout.vertcnt.end(); vidx += *iit++) {
			if (iit == outer_polygon) {
				continue;
			}

			size_t best_ofs,best_outer;
			float best_dist = 1e10;
			for(size_t vofs = 0; vofs < *iit; ++vofs) {
				const aiVector3D& v = meshout.verts[vidx+vofs];

				for(size_t outer = 0; outer < *outer_polygon; ++outer) {
					if (insertions[outer].get<0>()) {
						continue;
					}
					const aiVector3D& o = meshout.verts[outer_polygon_start+outer];
					const float d = (o-v).SquareLength();
										
					if (d < best_dist) {
						best_dist = d;
						best_ofs = vofs;
						best_outer = outer;
					}
				}		
			}
		
			// we will later insert a hidden connection line right after the closest point in the outer polygon
			insertions[best_outer] = boost::make_tuple(*iit,vidx,best_ofs);
		}

		// now that we collected all vertex connections to be added, build the output polygon
		cnt = *outer_polygon;
		for(size_t outer = 0; outer < *outer_polygon; ++outer) {
			const aiVector3D& o = meshout.verts[outer_polygon_start+outer];
			result.verts.push_back(o);

			const InsertionPoint& ins = insertions[outer];
			if (!ins.get<0>()) {
				continue;
			}

			for(size_t i = ins.get<2>(); i < ins.get<0>(); ++i) {
				result.verts.push_back(meshout.verts[ins.get<1>() + i]);
			}
			for(size_t i = 0; i < ins.get<2>(); ++i) {
				result.verts.push_back(meshout.verts[ins.get<1>() + i]);
			}

			// we need the first vertex of the inner polygon twice as we return to the
			// outer loop through the very same connection through which we got there.
			result.verts.push_back(meshout.verts[ins.get<1>() + ins.get<2>()]);

			// also append a copy of the initial insertion point to be able to continue the outer polygon
			result.verts.push_back(o);
			cnt += ins.get<0>()+2;
		}
		result.vertcnt.push_back(cnt);
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessPolyLine(const IFC::IfcPolyline& def, TempMesh& meshout, ConversionData& conv)
{
	// this won't produce a valid mesh, it just spits out a list of vertices
	aiVector3D t;
	BOOST_FOREACH(const IFC::IfcCartesianPoint& cp, def.Points) {
		ConvertCartesianPoint(t,cp);
		meshout.verts.push_back(t);
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessClosedProfile(const IFC::IfcArbitraryClosedProfileDef& def, TempMesh& meshout, ConversionData& conv)
{
	if(const IFC::IfcPolyline* poly = def.OuterCurve->ToPtr<IFC::IfcPolyline>()) {
		ProcessPolyLine(*poly,meshout,conv);
		if(meshout.verts.size()>2 && meshout.verts.front() == meshout.verts.back()) {
			meshout.verts.pop_back(); // duplicate element, first==last
		}
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcArbitraryClosedProfileDef entity, type is " + def.GetClassName());
		return;
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessOpenProfile(const IFC::IfcArbitraryOpenProfileDef& def, TempMesh& meshout, ConversionData& conv)
{
	if(const IFC::IfcPolyline* poly = def.Curve->ToPtr<IFC::IfcPolyline>()) {
		ProcessPolyLine(*poly,meshout,conv);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcArbitraryClosedProfileDef entity, type is " + def.GetClassName());
		return;
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessParametrizedProfile(const IFC::IfcParameterizedProfileDef& def, TempMesh& meshout, ConversionData& conv)
{
	if(const IFC::IfcRectangleProfileDef* cprofile = def.ToPtr<IFC::IfcRectangleProfileDef>()) {
		const float x = cprofile->XDim*0.5f, y = cprofile->YDim*0.5f;

		meshout.verts.reserve(meshout.verts.size()+4);
		meshout.verts.push_back( aiVector3D( x, y, 0.f ));
		meshout.verts.push_back( aiVector3D(-x, y, 0.f ));
		meshout.verts.push_back( aiVector3D(-x,-y, 0.f ));
		meshout.verts.push_back( aiVector3D( x,-y, 0.f ));
		meshout.vertcnt.push_back(4);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcParameterizedProfileDef entity, type is " + def.GetClassName());
		return;
	}

	aiMatrix4x4 trafo;
	ConvertAxisPlacement(trafo, *def.Position,conv);

	BOOST_FOREACH(aiVector3D& v, meshout.verts) {
		v *= trafo;
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessExtrudedAreaSolid(const IFC::IfcExtrudedAreaSolid& solid, TempMesh& result, ConversionData& conv)
{
	TempMesh meshout;
	if(const IFC::IfcArbitraryClosedProfileDef* cprofile = solid.SweptArea->ToPtr<IFC::IfcArbitraryClosedProfileDef>()) {
		ProcessClosedProfile(*cprofile,meshout,conv);
	}
	else if(const IFC::IfcArbitraryOpenProfileDef* copen = solid.SweptArea->ToPtr<IFC::IfcArbitraryOpenProfileDef>()) {
		ProcessOpenProfile(*copen,meshout,conv);
	}
	else if(const IFC::IfcParameterizedProfileDef* cparam = solid.SweptArea->ToPtr<IFC::IfcParameterizedProfileDef>()) {
		ProcessParametrizedProfile(*cparam,meshout,conv);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcProfileDef entity, type is " + solid.SweptArea->GetClassName());
		return;
	}

	if(meshout.verts.size()<=1) {
		return;
	}

	aiVector3D dir;
	ConvertDirection(dir,solid.ExtrudedDirection);

	dir *= solid.Depth;

	// assuming that `meshout.verts` is now a list of vertex points forming 
	// the underlying profile, extrude along the given axis, forming new
	// triangles.
	
	const std::vector<aiVector3D>& in = meshout.verts;
	const size_t size=in.size();

	const bool has_area = solid.SweptArea->ProfileType == "AREA" && size>2;

	result.verts.reserve(size*(has_area?4:2));
	result.vertcnt.reserve(meshout.vertcnt.size()+2);

	for(size_t i = 0; i < size; ++i) {
		const size_t next = (i+1)%size;

		result.vertcnt.push_back(4);

		result.verts.push_back(in[i]);
		result.verts.push_back(in[next]);
		result.verts.push_back(in[next]+dir);
		result.verts.push_back(in[i]+dir);
	}

	if(has_area) {
		// leave the triangulation of the profile area to the ear cutting 
		// implementation in aiProcess_Triangulate - for now we just
		// feed in a possibly huge polygon.
		for(size_t i = size; i--; ) {
			result.verts.push_back(in[i]+dir);
		}
		for(size_t i = 0; i < size; ++i ) {
			result.verts.push_back(in[i]);
		}
		result.vertcnt.push_back(size);
		result.vertcnt.push_back(size);
	}

	aiMatrix4x4 trafo;
	ConvertAxisPlacement(trafo, solid.Position,conv);

	aiVector3D vavg;
	BOOST_FOREACH(aiVector3D& v, result.verts) {
		v *= trafo;
		vavg += v;
	}

	// fixup face orientation.
	vavg /= static_cast<float>( result.verts.size() );

	size_t c = 0;
	BOOST_FOREACH(unsigned int cnt, result.vertcnt) {
		if (cnt>2){
			const aiVector3D& thisvert = result.verts[c];
			const aiVector3D normal((thisvert-result.verts[c+1])^(thisvert-result.verts[c+2]));
			if (normal*(thisvert-vavg) < 0) {
				std::reverse(result.verts.begin()+c,result.verts.begin()+cnt+c);
			}
		}
		c += cnt;
	}

	IFCImporter::LogDebug("generate mesh procedurally by extrusion (IfcExtrudedAreaSolid)");
}

// ------------------------------------------------------------------------------------------------
void ProcessSweptAreaSolid(const IFC::IfcSweptAreaSolid& swept, TempMesh& meshout, ConversionData& conv)
{
	if(const IFC::IfcExtrudedAreaSolid* solid = swept.ToPtr<IFC::IfcExtrudedAreaSolid>()) {
		ProcessExtrudedAreaSolid(*solid,meshout,conv);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcSweptAreaSolid entity, type is " + swept.GetClassName());
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessBoolean(const IFC::IfcBooleanResult& boolean, TempMesh& meshout, ConversionData& conv)
{
	if(const IFC::IfcBooleanClippingResult* const clip = boolean.ToPtr<IFC::IfcBooleanClippingResult>()) {
		if(const IFC::IfcBooleanResult* const op0 = clip->FirstOperand->ResolveSelectPtr<IFC::IfcBooleanResult>(conv.db)) {
			ProcessBoolean(*op0,meshout,conv);
		}
		else if (const IFC::IfcSweptAreaSolid* const swept = clip->FirstOperand->ResolveSelectPtr<IFC::IfcSweptAreaSolid>(conv.db)) {
			//ProcessSweptAreaSolid(*swept,meshout,conv);
			// XXX
		}
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcBooleanResult entity, type is " + boolean.GetClassName());
	}
}

// ------------------------------------------------------------------------------------------------
int ConvertShadingMode(const std::string& name)
{
	if (name == "BLINN") {
		return aiShadingMode_Blinn;
	}
	else if (name == "FLAT" || name == "NOTDEFINED") {
		return aiShadingMode_NoShading;
	}
	else if (name == "PHONG") {
		return aiShadingMode_Phong;
	}
	IFCImporter::LogWarn("shading mode "+name+" not recognized by Assimp, using Phong instead");
	return aiShadingMode_Phong;
}

// ------------------------------------------------------------------------------------------------
unsigned int ProcessMaterials(const IFC::IfcRepresentationItem& item, ConversionData& conv)
{
	aiString name;
	aiColor4D col;

	if (conv.materials.empty()) {
		std::auto_ptr<MaterialHelper> mat(new MaterialHelper());

		name.Set("<IFCDefault>");
		mat->AddProperty(&name,AI_MATKEY_NAME);

		col = aiColor4D(0.6f,0.6f,0.6f,1.0f);
		mat->AddProperty(&col,1, AI_MATKEY_COLOR_DIFFUSE);

		conv.materials.push_back(mat.release());
	}

	STEP::DB::RefMapRange range = conv.db.GetRefs().equal_range(item.GetID());
	for(;range.first != range.second; ++range.first) {
		if(const IFC::IfcStyledItem* const styled = conv.db.GetObject((*range.first).second)->ToPtr<IFC::IfcStyledItem>()) {
			BOOST_FOREACH(const IFC::IfcPresentationStyleAssignment& as, styled->Styles) {
				BOOST_FOREACH(const IFC::IfcPresentationStyleSelect* sel, as.Styles) {
			
					if (const IFC::IfcSurfaceStyle* surf =  sel->ResolveSelectPtr<IFC::IfcSurfaceStyle>(conv.db)) {
						const std::string side = static_cast<std::string>(surf->Side);
						if (side != "BOTH") {
							IFCImporter::LogWarn("ignoring surface side marker on IFC::IfcSurfaceStyle: " + side);
						}

						std::auto_ptr<MaterialHelper> mat(new MaterialHelper());

						name.Set((surf->Name? surf->Name.Get() : "IfcSurfaceStyle_Unnamed"));
						mat->AddProperty(&name,AI_MATKEY_NAME);

						// now see which kinds of surface information are present
						BOOST_FOREACH(const IFC::IfcSurfaceStyleElementSelect* sel2, surf->Styles) {

							if (const IFC::IfcSurfaceStyleShading* shade = sel2->ResolveSelectPtr<IFC::IfcSurfaceStyleShading>(conv.db)) {
								aiColor4D col_base;

								ConvertColor(col_base, shade->SurfaceColour);
								mat->AddProperty(&col,1, AI_MATKEY_COLOR_DIFFUSE);

								if (const IFC::IfcSurfaceStyleRendering* ren = shade->ToPtr<IFC::IfcSurfaceStyleRendering>()) {
									
									if (ren->DiffuseColour) {
										ConvertColor(col, ren->DiffuseColour.Get(),conv,&col_base);
										mat->AddProperty(&col,1, AI_MATKEY_COLOR_DIFFUSE);
									}

									if (ren->SpecularColour) {
										ConvertColor(col, ren->SpecularColour.Get(),conv,&col_base);
										mat->AddProperty(&col,1, AI_MATKEY_COLOR_SPECULAR);
									}

									if (ren->TransmissionColour) {
										ConvertColor(col, ren->TransmissionColour.Get(),conv,&col_base);
										mat->AddProperty(&col,1, AI_MATKEY_COLOR_TRANSPARENT);
									}

									if (ren->ReflectionColour) {
										ConvertColor(col, ren->ReflectionColour.Get(),conv,&col_base);
										mat->AddProperty(&col,1, AI_MATKEY_COLOR_REFLECTIVE);
									}

									const int shading = (ren->SpecularHighlight && ren->SpecularColour)?ConvertShadingMode(ren->ReflectanceMethod):aiShadingMode_Gouraud;
									mat->AddProperty(&shading,1, AI_MATKEY_SHADING_MODEL);

									if (ren->SpecularHighlight) {
										if(const EXPRESS::REAL* rt = ren->SpecularHighlight.Get()->ToPtr<EXPRESS::REAL>()) {
											// at this point we don't distinguish between the two distinct ways of
											// specifying highlight intensities. leave this to the user.
											const float e = *rt;
											mat->AddProperty(&e,1,AI_MATKEY_SHININESS);
										}
										else {
											IFCImporter::LogWarn("unexpected type error, SpecularHighlight should be a REAL");
										}
									}
								}
							}
							else if (const IFC::IfcSurfaceStyleWithTextures* tex = sel2->ResolveSelectPtr<IFC::IfcSurfaceStyleWithTextures>(conv.db)) {
								// XXX
							}
						}

						conv.materials.push_back(mat.release());
						return conv.materials.size()-1;
					}
				}
			}
		}
	}
	return 0;
}

// ------------------------------------------------------------------------------------------------
void ProcessTopologicalItem(const IFC::IfcTopologicalRepresentationItem& topo, std::vector<unsigned int>& mesh_indices, ConversionData& conv)
{
	TempMesh meshtmp;
	if(const IFC::IfcConnectedFaceSet* fset = topo.ToPtr<IFC::IfcConnectedFaceSet>()) {
		ProcessConnectedFaceSet(*fset,meshtmp,conv);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcTopologicalRepresentationItem entity, type is " + topo.GetClassName());
		return;
	}

	aiMesh* const mesh = meshtmp.ToMesh();
	if(mesh) {
		mesh->mMaterialIndex = ProcessMaterials(topo,conv);
		mesh_indices.push_back(conv.meshes.size());
		conv.meshes.push_back(mesh);
	}
}

// ------------------------------------------------------------------------------------------------
void ProcessGeometricItem(const IFC::IfcGeometricRepresentationItem& geo, std::vector<unsigned int>& mesh_indices, ConversionData& conv)
{
	TempMesh meshtmp;
	if(const IFC::IfcShellBasedSurfaceModel* shellmod = geo.ToPtr<IFC::IfcShellBasedSurfaceModel>()) {
		BOOST_FOREACH(const IFC::IfcShell* shell,shellmod->SbsmBoundary) {
			try {
				const EXPRESS::ENTITY& e = shell->To<IFC::ENTITY>();
				const IFC::IfcConnectedFaceSet& fs = conv.db.MustGetObject(e).To<IFC::IfcConnectedFaceSet>(); 

				ProcessConnectedFaceSet(fs,meshtmp,conv);
			}
			catch(std::bad_cast&) {
				IFCImporter::LogWarn("unexpected type error, IfcShell ought to inherit from IfcConnectedFaceSet");
				continue;
			}
		}
	}
	else if(const IFC::IfcSweptAreaSolid* swept = geo.ToPtr<IFC::IfcSweptAreaSolid>()) {
		ProcessSweptAreaSolid(*swept,meshtmp,conv);
	}
	else if(const IFC::IfcManifoldSolidBrep* brep = geo.ToPtr<IFC::IfcManifoldSolidBrep>()) {
		ProcessConnectedFaceSet(brep->Outer,meshtmp,conv);
	}
	else if(const IFC::IfcBooleanResult* boolean = geo.ToPtr<IFC::IfcBooleanResult>()) {
		ProcessBoolean(*boolean,meshtmp,conv);
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcGeometricRepresentationItem entity, type is " + geo.GetClassName());
		return;
	}

	aiMesh* const mesh = meshtmp.ToMesh();

	if(mesh) {
		mesh->mMaterialIndex = ProcessMaterials(geo,conv);
		mesh_indices.push_back(conv.meshes.size());
		conv.meshes.push_back(mesh);
	}
}

// ------------------------------------------------------------------------------------------------
void AssignAddedMeshes(std::vector<unsigned int>& mesh_indices,aiNode* nd,ConversionData& conv)
{
	if (!mesh_indices.empty()) {

		// make unique
		std::sort(mesh_indices.begin(),mesh_indices.end());
		std::vector<unsigned int>::iterator it_end = std::unique(mesh_indices.begin(),mesh_indices.end());
		
		const size_t size = std::distance(mesh_indices.begin(),it_end);

		nd->mNumMeshes = size;
		nd->mMeshes = new unsigned int[nd->mNumMeshes];
		for(unsigned int i = 0; i < nd->mNumMeshes; ++i) {
			nd->mMeshes[i] = mesh_indices[i];
		}
	}
}

// ------------------------------------------------------------------------------------------------
bool TryQueryMeshCache(const IFC::IfcRepresentationItem& item, std::vector<unsigned int>& mesh_indices, ConversionData& conv) 
{
	ConversionData::MeshCache::const_iterator it = conv.cached_meshes.find(&item);
	if (it != conv.cached_meshes.end()) {
		std::copy((*it).second.begin(),(*it).second.end(),std::back_inserter(mesh_indices));
		return true;
	}
	return false;
}

// ------------------------------------------------------------------------------------------------
void PopulateMeshCache(const IFC::IfcRepresentationItem& item, const std::vector<unsigned int>& mesh_indices, ConversionData& conv)
{
	conv.cached_meshes[&item] = mesh_indices;
}

// ------------------------------------------------------------------------------------------------
bool ProcessRepresentationItem(const IFC::IfcRepresentationItem& item, std::vector<unsigned int>& mesh_indices, ConversionData& conv)
{
	// XXX should we make a choice? handle only one of them?
	if(const IFC::IfcTopologicalRepresentationItem* const topo = item.ToPtr<IFC::IfcTopologicalRepresentationItem>()) {
		if (!TryQueryMeshCache(item,mesh_indices,conv)) {
			ProcessTopologicalItem(*topo,mesh_indices,conv);
			PopulateMeshCache(item,mesh_indices,conv);
		}
		
	}
	else if(const IFC::IfcGeometricRepresentationItem* const geo = item.ToPtr<IFC::IfcGeometricRepresentationItem>()) {
		if (!TryQueryMeshCache(item,mesh_indices,conv)) {
			ProcessGeometricItem(*geo,mesh_indices,conv);	
			PopulateMeshCache(item,mesh_indices,conv);
		}
	}
	else {
		return false;
	}

	return true;
}

// ------------------------------------------------------------------------------------------------
void ResolveObjectPlacement(aiMatrix4x4& m, const IFC::IfcObjectPlacement& place, ConversionData& conv)
{
	if (const IFC::IfcLocalPlacement* const local = place.ToPtr<IFC::IfcLocalPlacement>()){
		ConvertAxisPlacement(m, *local->RelativePlacement, conv);

		if (local->PlacementRelTo) {
			aiMatrix4x4 tmp;
			ResolveObjectPlacement(tmp,local->PlacementRelTo.Get(),conv);
			m = tmp * m;
		}
	}
	else {
		IFCImporter::LogWarn("skipping unknown IfcObjectPlacement entity, type is " + place.GetClassName());
	}
}

// ------------------------------------------------------------------------------------------------
void GetAbsTransform(aiMatrix4x4& out, const aiNode* nd, ConversionData& conv)
{
	aiMatrix4x4 t;
	if (nd->mParent) {
		GetAbsTransform(t,nd->mParent,conv);
	}
	out = t*nd->mTransformation;
}

// ------------------------------------------------------------------------------------------------
void ProcessMappedItem(const IFC::IfcMappedItem& mapped, aiNode* nd_src, std::vector< aiNode* >& subnodes_src, ConversionData& conv)
{
	// insert a custom node here, the cartesian transform operator is simply a conventional transformation matrix
	std::auto_ptr<aiNode> nd(new aiNode());
	nd->mName.Set("MappedItem");
	
	std::vector<unsigned int> meshes;

	const IFC::IfcRepresentation& repr = mapped.MappingSource->MappedRepresentation;
	BOOST_FOREACH(const IFC::IfcRepresentationItem& item, repr.Items) {
		if(!ProcessRepresentationItem(item,meshes,conv)) {
			IFCImporter::LogWarn("skipping unknown IfcMappedItem entity, type is " + item.GetClassName());
		}
	}
	AssignAddedMeshes(meshes,nd.get(),conv);
		
	// handle the cartesian operator
	aiMatrix4x4 m;
	ConvertTransformOperator(m, *mapped.MappingTarget);

	aiMatrix4x4 msrc;
	ConvertAxisPlacement(msrc,*mapped.MappingSource->MappingOrigin,conv);

	aiMatrix4x4 minv = msrc;
	minv.Inverse();

	//aiMatrix4x4 correct;
	//GetAbsTransform(correct,nd_src,conv);

	nd->mTransformation = nd_src->mTransformation * minv * m * msrc;
	subnodes_src.push_back(nd.release());
}

// ------------------------------------------------------------------------------------------------
void ProcessProductRepresentation(const IFC::IfcProduct& el, aiNode* nd, std::vector< aiNode* >& subnodes, ConversionData& conv)
{
	if(!el.Representation) {
		return;
	}

	if(conv.settings.skipSpaceRepresentations) {
		if(const IFC::IfcSpace* const space = el.ToPtr<IFC::IfcSpace>()) {
			IFCImporter::LogWarn("skipping space representation due to importer settings");
			return;
		}
	}

	std::vector<unsigned int> meshes;
	
	BOOST_FOREACH(const IFC::IfcRepresentation& repr, el.Representation.Get()->Representations) {
		if (conv.settings.skipCurveRepresentations && repr.RepresentationType && repr.RepresentationType.Get() == "Curve2D") {
			IFCImporter::LogWarn("skipping Curve2D representation item due to importer settings");
			return;
		}
		BOOST_FOREACH(const IFC::IfcRepresentationItem& item, repr.Items) {
			if(!ProcessRepresentationItem(item,meshes,conv)) {
				if(const IFC::IfcMappedItem* const geo = item.ToPtr<IFC::IfcMappedItem>()) {
					ProcessMappedItem(*geo,nd,subnodes,conv);			
				}
				else {
					IFCImporter::LogWarn("skipping unknown IfcRepresentationItem entity, type is " + item.GetClassName());
				}
			}
		}
	}

	AssignAddedMeshes(meshes,nd,conv);
}

// ------------------------------------------------------------------------------------------------
aiNode* ProcessSpatialStructure(aiNode* parent, const IFC::IfcProduct& el, ConversionData& conv)
{
	const STEP::DB::RefMap& refs = conv.db.GetRefs();

	// add an output node for this spatial structure
	std::auto_ptr<aiNode> nd(new aiNode());
	nd->mName.Set(el.GetClassName()+"_"+(el.Name?el.Name:el.GlobalId));
	nd->mParent = parent;

	if(el.ObjectPlacement) {
		ResolveObjectPlacement(nd->mTransformation,el.ObjectPlacement.Get(),conv);
	}

	// convert everything contained directly within this structure,
	// this may result in more nodes.
	std::vector< aiNode* > subnodes;
	try {

		ProcessProductRepresentation(el,nd.get(),subnodes,conv);

		// locate aggregates and 'contained-in-here'-elements of this spatial structure and add them in recursively
		STEP::DB::RefMapRange range = refs.equal_range(el.GetID());

		for(STEP::DB::RefMapRange range2=range;range2.first != range.second; ++range2.first) {
			if(const IFC::IfcRelContainedInSpatialStructure* const cont = conv.db.GetObject((*range2.first).second)->
				ToPtr<IFC::IfcRelContainedInSpatialStructure>()) {
				
				BOOST_FOREACH(const IFC::IfcProduct& pro, cont->RelatedElements) {		
					subnodes.push_back( ProcessSpatialStructure(nd.get(),pro,conv) );
				}
				break;
			}
		}

		for(;range.first != range.second; ++range.first) {
			if(const IFC::IfcRelAggregates* const aggr = conv.db.GetObject((*range.first).second)->ToPtr<IFC::IfcRelAggregates>()) {

				// move aggregate elements to a separate node since they are semantically different than elements that are merely 'contained'
				std::auto_ptr<aiNode> nd_aggr(new aiNode());
				nd_aggr->mName.Set("$Aggregates");
				nd_aggr->mParent = nd.get();

				nd_aggr->mChildren = new aiNode*[aggr->RelatedObjects.size()]();
				BOOST_FOREACH(const IFC::IfcObjectDefinition& def, aggr->RelatedObjects) {
					if(const IFC::IfcProduct* const prod = def.ToPtr<IFC::IfcProduct>()) {
						nd_aggr->mChildren[nd_aggr->mNumChildren++] = ProcessSpatialStructure(nd_aggr.get(),*prod,conv);
					}
				}
			
				subnodes.push_back( nd_aggr.release() );
				break;
			}
		}

		if (subnodes.size()) {
			nd->mChildren = new aiNode*[subnodes.size()]();
			BOOST_FOREACH(aiNode* nd2, subnodes) {
				nd->mChildren[nd->mNumChildren++] = nd2;
				nd2->mParent = nd.get();
			}
		}
	}
	catch(...) {
		// it hurts, but I don't want to pull boost::ptr_vector into -noboost only for these few spots here
		std::for_each(subnodes.begin(),subnodes.end(),delete_fun<aiNode>());
		throw;
	}

	return nd.release();
}

// ------------------------------------------------------------------------------------------------
void ProcessSpatialStructures(ConversionData& conv)
{
	// process all products in the file. it is reasonable to assume that a
	// file that is relevant for us contains at least a site or a building.
	const STEP::DB::ObjectMapByType& map = conv.db.GetObjectsByType();
	STEP::DB::ObjectMapRange range = map.equal_range("ifcsite");

	if (range.first == map.end()) {
		range = map.equal_range("ifcbuilding");
		if (range.first == map.end()) {
			// no site, no building - try all ids. this will take ages, but it should rarely happen.
			range = STEP::DB::ObjectMapRange(map.begin(),map.end());
		}
	}

	
	for(;range.first != range.second; ++range.first) {
		const IFC::IfcSpatialStructureElement* const prod = (*range.first).second->ToPtr<IFC::IfcSpatialStructureElement>();
		if(!prod) {
			continue;
		}
		IFCImporter::LogDebug("looking at spatial structure `" + (prod->Name ? prod->Name.Get() : "unnamed") + "`" + (prod->ObjectType? " which is of type " + prod->ObjectType.Get():""));
	
		// the primary site is referenced by an IFCRELAGGREGATES element which assigns it to the IFCPRODUCT
		const STEP::DB::RefMap& refs = conv.db.GetRefs();
		STEP::DB::RefMapRange range = refs.equal_range(conv.proj.GetID());
		for(;range.first != range.second; ++range.first) {
			if(const IFC::IfcRelAggregates* const aggr = conv.db.GetObject((*range.first).second)->ToPtr<IFC::IfcRelAggregates>()) {
			
				BOOST_FOREACH(const IFC::IfcObjectDefinition& def, aggr->RelatedObjects) {
					// comparing pointer values is not sufficient, we would need to cast them to the same type first
					// as there is multiple inheritance in the game.
					if (def.GlobalId == prod->GlobalId) { 
						IFCImporter::LogDebug("selecting this spatial structure as root structure");
						// got it, this is the primary site.
						conv.out->mRootNode = ProcessSpatialStructure(NULL,*prod,conv);
						return;
					}
				}

			}
		}
	}


	IFCImporter::ThrowException("Failed to determine primary site element");
}

// ------------------------------------------------------------------------------------------------
void MakeTreeRelative(aiNode* start, const aiMatrix4x4& combined)
{
	// combined is the parent's absolute transformation matrix
	aiMatrix4x4 old = start->mTransformation;

	if (!combined.IsIdentity()) {
		start->mTransformation = aiMatrix4x4(combined).Inverse() * start->mTransformation;
	}

	// All nodes store absolute transformations right now, so we need to make them relative
	for (unsigned int i = 0; i < start->mNumChildren; ++i) {
		MakeTreeRelative(start->mChildren[i],old);
	}
}

// ------------------------------------------------------------------------------------------------
void MakeTreeRelative(ConversionData& conv)
{
	MakeTreeRelative(conv.out->mRootNode,aiMatrix4x4());
}

} // !anon



#endif