What's a Brep Face if it is NOT a Surface


I was debugging some .Net code where I loop through all the faces of a Brep (Essentially a Box which was cut - through boolean split- with a Nurbs Surface.

I was testing using the “.IsSurface” property of the brep face and got (5 out of 6 times) the answer “false”.
So, it the BrepFace is not a Surface, what is it then? What does this method test? Is it returning “false” if it is a trimmed surface?


You are correct: BrepFace.IsSurface is only true if it is a non-trimmed surface.

See also: http://4.rhino3d.com/5/rhinocommon/html/P_Rhino_Geometry_BrepFace_IsSurface.htm
and http://wiki.mcneel.com/developer/brepstructure for more information on the concept of BREP in Rhino.

Thanks. That helps a lot.