Module profile_lower

Lower Derived and Composite profiles onto the concrete builders (ADR 0054).

Derived

A derived profile is a basis plus an affine transform. Lowering it means pushing the transform down onto the basis geometry, which is only sound when the transform preserves the SHAPE KIND of what it moves:

• A circle stays a circle only under a CONFORMAL (similarity) linear part. A non-uniform scale or a shear turns it into an ellipse, which this crate cannot extrude, so those are refused rather than silently relabelled. Note a shear has determinant 1, so a determinant check alone would let it through.
• A negative determinant MIRRORS, reversing ring orientation. The extruders assume counter-clockwise outer rings, so mirrored rings are reversed on lowering rather than handed over inside-out.

Composite

Profile::Composite is the IfcCompositeProfileDef case: several profiles acting as ONE section. Members may touch or overlap, so they are unioned rather than concatenated – concatenating overlapping members would double-count the shared area and produce self-intersecting walls.

The exact extrusion and revolution use composite_regions, which unions the members’ exact contours – arcs and member holes included – over one ArcArrangement (ADR 0072) and returns every connected piece. Disjoint members become separate solids in one ExactBRep (#111). lower_composite is the older polygon union, kept for its callers; it refuses arcs, member holes and disjoint members.

Structs

CompositeRegion

One connected piece of a composite section.

Functions

composite_regions

Union a composite’s members exactly and return every connected piece.

lower_composite

Union the members of a composite profile into one section.

lower_derived

Push an affine transform down onto a basis profile.