Fri, 05/12/2000 - 15:59
Forums:
I am having a little trouble with OpenCascade's IGES import routines. The IGES entity I am principally interested in is number 128, and I would like to represent this in OpenCascade as a Geom_BSplineSurface object, but the IGES example code I have looked at all deals with using Topological representations, rather than Geometric ones. Can I directly import my IGES 128 entities into Geom_BSplineSurface forms, or do I need to read into TopoDS_Shapes and convert?
Fri, 05/12/2000 - 16:22
Hello,
Open CASCADE data exchange processors (IGES and STEP) are intended to transfer data between Open CASCADE topology (given as TopoDS_Shape) and neutral format entities. Of course, mapping at the level of geometry also exists but it is an intermediate level, while topology is an API.
To recover a geometrical surface (Geom_Surface) from received topological face (TopoDS_Face) you can use:
IGESControlStd_Reader aReader = ...;
...
TopoDS_Shape aResult = aReader.OneShape();
for (TopExp_Explorer anExp (aResult, TopAbs_FACE); anExp.More(); anExp.Next()) {
TopoDS_Face aFace = anExp.Current();
Handle(Geom_Surface) aSurface = BRep_Tool::Surface (aFace);
// working with aSurface
if (aSurface->IsKind (STANDARD_TYPE (Geom_BSplineSurface)) {
...
}
}
If you are extremely interested in the intermediary level of mapping geometry, please have a look at IGESToBRep_BasisSurface class.
Best regards, Roman
Tue, 11/13/2007 - 14:38
Hi
Any example code to use this class IGESToBRep_TopoSurface ?
Say I have OCC geometrical surface (for eg. spherical surface or rect. trimmed cylindrical surface ) and toplogical face ( b-spline surface with a circular hole in between).
Now I export these surfaces/face in IGES format.
When I read it back using the OCC IGES reader, I should be able to read the geometrical surfaces as OCC geometrical surfaces and the toplogical face as OCC brep face itself.
Can the above class help in this regard ???