Writing IFC - no success with IfcSurfaceCurveSweptAreaSolid

Developers
1

Dear community,

I’m writing an IFC export interface class for a metal stair design software which runs well regarding all straight profiles and bended parts using C#.

But I’m struggling since days with generating parts of helix type. E.g. I need to export handrails of a spiral stair made from flat profile and that flat must keep the upright orientation.

What I found out is that ‘IfcSurfaceCurveSweptAreaSolid’ is my friend, but we don’t come together. I simply have no success.

I think I have a basic missunderstanding of how Directrix and reference surface must work together, therefore I think posting my successless code makes no sense.

If someone here is familiar with that, I would be happy to get a small running example. What I need is exactly that what is described in the documentation under 8.8.3.41and shown in Figure 8.8.3.41.A.

Thanks, Norbert

2

Hi Norbert,

How do you measure success? Correct visualization in a viewer? If so, which one(s)? I don’t believe IfcSurfaceCurveSweptAreaSolid is included in Model View Definitions such as coordination view, so it’s use will be quite minimal and many viewers will likely not support it.
If you are looking for 3rd party validation of what you are generating, then I have implemented creation of a rhino3d surface in the Geometry Gym IFC plugin (ggRhinoIFC which can be installed as per Installation | Geometry Gym). There are free evaluation licenses for Rhino3d and our plugin. If you don’t wish to install, you can generate a sample and send it (privately or publicly) and I will have a quick review (others here might do the same).

Cheers,

Jon

3

Jon, thanks a lot. Yes, the question is how to define success, as everytime in life.

I tried with two viewers, OpenIFCViewer and BimVision and with a 3D profile based CAD System named HiCAD.

And meanwhile I exported such a helix type profile from other CAD systems and found out, they are not able to do or they do it as Brep.

So I decided for me to use Brep as well, what is an easy job because I already have them generated in my CAD library inside my application.

But Breps are only nice to view, they make no sense regarding part lists or editing the construction, that was the reason I tried anther way before.

Kind regards,
Norbert