CV-2x3-135 (aka CV-06-135)
Assignment of surface color to surface models (dealing with the backface issue)
Based on IFC2x3
Initiator ISG Meeting-Waltham
Effects Extended Coordination View
Date 2007 03 13
Surface model maybe based on open or closed shells. If backfaces should not be shown differently then the frontface (and in an open shell there is no front and back), the surface style should be assigned as applying to both faces.
This is handled by
* IfcSurfaceStyle.Side = .BOTH.
It would be wrong and excluded from certification to export the face twice, i.e. with a normal to point in both directions.