BetaBetaAdds a roof over a rectangle of a storey: flat, sloping one way, gabled, or hipped on all four
sides. Every slope has the same pitch; its underside meets the outline at baseOffset above
the storey's floor and reaches overhang past it on every side.
The model, the storey, the rectangle, the roof's shape, pitch, thickness and overhang
A new model with the roof
Roofs: flat, mono-pitch, gable and hip roofs over a rectangle, each an
IfcRoofwhose parts are the sloping slabs of its planes. Walls are clipped under a roof withwalls.clipByRoof.