Module hatch 

Hatching in parametric space: parallel lines clipped to a face’s trim.

The rings are the same chart boundary every other consumer walks (face_boundary), so the hatch and the triangulation cannot disagree about where the face is. The lines run at an angle in the chart, spaced evenly, and each is cut to the inside intervals by even-odd crossing counting; holes split segments the same way they split everything else.

Scanlines sit at half-spacing offsets, so a boundary lying exactly on a round coordinate (every axis-aligned face) is not grazed.

Functions

hatch_face

Hatch a face’s chart with parallel lines.