IFC Syntax : Geometry Brep, CSG and Clipping

Boundary representation (Brep) describes a solid by explicitly listing the surfaces, edges and vertices that bound it, instead of by a parametric recipe such as an extrusion. Brep is the escape hatch of IFC geometry : imported meshes, free-form shapes, anything a tool cannot round-trip as a swept solid. This skill also owns CSG (Boolean combinations of solids) and clipping (the half-space subtract that cuts openings and sloped tops into extruded elements).

Applies to IFC2x3, IFC4, and IFC4.3. The faceted Brep, CSG and clipping families exist from IFC2x3 ; the advanced (curved-face) Brep family is IFC4 and later. See Version Differences.

Quick Reference

When to use Brep, CSG, or clipping