Module contour_lower

Lower an arbitrary contour profile onto the arc-ring extruder (ADR 0053).

Why this is an adapter, not new geometry

ContourProfile carries segments of any Curve2 kind. The arc-ring extruder already builds exact walls for the two kinds that matter here – Line2 becomes a planar wall, Circle2 becomes a cylindrical one – so lowering a contour to an ArcRing is a translation, not a construction.

Anything else is REFUSED rather than sampled. Tessellating an ellipse or a spline into short chords would produce a solid that looks right, passes every closure check, and silently is not the requested shape.

Functions

arc_ring_signed_area

Signed area of a bulge-encoded ring; positive when counter-clockwise.

contour_to_arc_ring

Convert one closed contour into an arc ring.

orient_arc_ring

Force a ring to the winding a boundary role requires.

reverse_arc_ring

Reverse an arc ring in place, preserving its arcs.