Module wire2d 

Offsetting a closed planar wire: the sketch-plane operation everything in this crate stands on.

Each edge is offset on its own (a segment to the parallel segment, an arc to the concentric arc) and the corners decide the rest. Where the corner turns away from the offset side the pieces separate, and the gap is closed by the chosen join: an arc about the old corner, or the extension of both pieces to their meeting. Where it turns toward the offset side the pieces overlap, and both are trimmed to their intersection. The result is a new wire with history: every input edge modified into its offset, every join generated from the corner it rounds.

The limits, refused by name: edges that are neither straight nor circular, a corner trim that consumes an offset edge whole, an arc whose concentric offset has no radius left, and an offset that consumes the wire whole. Where the raw offset crosses itself it is split there, and each sub-piece stands or falls by the offset’s own definition (a point of the true offset boundary is a full offset from the source, a collapsed sliver is closer), so an offset the collapse severs into islands comes back as a compound of loops.

Enums

Join

How a gap at a corner is closed: by a planar wire’s offset, or where a thick solid’s walls meet across an edge.

Functions

offset_wire

Offset a closed planar wire by offset: positive moves outward, away from the enclosed region, negative moves inward.