Bad openings

[ghost]

Hello,

I have a problem with some openings in walls as you can see in this capture done in a build of SimpleViewerExampleQt using the last ifc++ source ( 2021 - 05 - 05 ).

The problem does not appear in the build version of the viewer available to download on the website :

Even if there's another problem on the window on the right of the image.

Here is the same wall viewed in BimVision :

And here is the IFC file containing this wall.

buggy.zip

Thanks for the good job !

Stéphane

[ifcquery]

Carve is the library here used for boolean operations: https://github.com/folded/carve
Probably the issue above has to do with the epsilon value used by carve to determine whether a point is in a plane or not.
You can change this value like this: GeometryConverter::setCsgEps(double eps)

[ghost]

Thanks for your answer, I've tried different values from 1.5e-1

to 1.5e-15

but, unfortunately, it does not fix the problem.

[ifcquery]

CSG operations are a field of its own, that's why it is an external library.
There are possible ways to improve this:

• improve the carve library
• fix and re-triangulate the complete mesh before each subtraction of an opening
  Let me know if you find an improvement :)

[ghost]

Thank you for your answer. With your clues, one of our developer fixed the issue inserting this line :

CSG_Adapter::retriangulateMeshSet( product_meshset );

in RepresentationConverter.h , line 1083, just before

CSG_Adapter::computeCSG( product_meshset, opening_meshset, carve::csg::CSG::A_MINUS_B, result, this, ifc_element );

Perhaps it should be a good idea to propose it as an option in GeometrySettings ?

[ifcquery]

"as an option in GeometrySettings". Good idea, I will put that in the next update soon

[cesss]

I'm interested in this 😃

[ifcquery]

Should be improved with latest update. Yet not perfect...