Problems Exporting Pre-tessellated Geometry to STEP

Hello,

I'm working with a large project that is using Occ 6.9.0. I need to write out triangular meshes as STEP files. The meshes are just collections of vertices and vertex indices as would be used in an OpenGL render buffer.

I've tried the following, incomplete, code which gets a wireframe STEP file but is quite slow on export.

for( int p=0; p<srcMesh.m_indx.Length(); p+=3 )
{
	int v0 = srcMesh.m_indx[p+0];
	int v1 = srcMesh.m_indx[p+1];
	int v2 = srcMesh.m_indx[p+2];

	BRepBuilderAPI_MakePolygon poly;
	poly.Add( gp_Pnt(srcMesh.m_vert[v0].x, srcMesh.m_vert[v0].y, srcMesh.m_vert[v0].z) );
	poly.Add( gp_Pnt(srcMesh.m_vert[v1].x, srcMesh.m_vert[v1].y, srcMesh.m_vert[v1].z) );
	poly.Add( gp_Pnt(srcMesh.m_vert[v2].x, srcMesh.m_vert[v2].y, srcMesh.m_vert[v2].z) );
	poly.Close();

	TopoDS_Shape shape = poly.Shape();

	status = aWriter.Transfer( shape, STEPControl_AsIs );
}

So I tried the following which I had hoped would be faster.

STEPControl_Writer aWriter;
BRep_Builder builder;

...

TColgp_Array1OfPnt points(1, (Standard_Integer)srcMesh.m_vert.Length());
for( int v=0; v<srcMesh.m_vert.Length(); ++v )
{
	points(v+1) = gp_Pnt(srcMesh.m_vert[v].x, srcMesh.m_vert[v].y, srcMesh.m_vert[v].z);
}

Poly_Array1OfTriangle tris(1, (Standard_Integer)srcMesh.m_indx.Length()/ 3);
for( int p=0, q=1; p<srcMesh.m_indx.Length(); p+=3, ++q )
{
	int v0 = srcMesh.m_indx[p+0];
	int v1 = srcMesh.m_indx[p+1];
	int v2 = srcMesh.m_indx[p+2];
	tris.ChangeValue(q) = Poly_Triangle( v0+1, v1+1, v2+1 );
}

Poly_Triangulation * triangulation = new Poly_Triangulation( points, tris );
TopoDS_Face face;
builder.MakeFace(face, triangulation);

status = aWriter.Transfer( face, STEPControl_FacetedBrep );
if( status != IFSelect_RetDone )
{
	printf("Failed %s\n", ToString(status));
}

The problem with the 2nd block of code is that STEPControl_Writer::Transfer() always returns IFSelect_RetFail because deep inside XSControl_Controller.cxx the function TransferFinder() fails to find a Transfer_Binder from a map it creates earlier in the process.

So is there a fast and correct way of transferring triangle data into the OpenCascade environment so it can be exported to STEP?

Is there a problem with the 2nd block of code that can easily be fixed or should I go with creating the triangles one at a time?

Thanks in advance.