I'd like use this fonction and I don't manage .Could you send me an example ? Thanks.
Sorry, but trimmed surfaces are not yet implemented in Geant4. The class defined in the BREPS module is meant to be used in the context of an interface to CAD systems for related STEP entities, but the current implementation is not yet complete.
Development abandoned since the existence of alternative approaches to import CAD geometries. Closing obsolete tickets left open...