Function hatch_face 

pub fn hatch_face(
    model: &Model,
    face: &Shape,
    angle: f64,
    spacing: f64,
    deflection: Deflection,
    tol: Tolerances,
) -> OgeomResult<Vec<[Point2; 2]>>

Hatch a face’s chart with parallel lines.

angle is the line direction in the chart, radians from the u axis; spacing the perpendicular distance between lines. Returns the clipped segments in chart coordinates, each as its two endpoints; lifting them to space is the surface’s own point_at, and which chart step is fine enough for that lift is the caller’s deflection question, not this one.

Errors

OgeomError::Construction if the spacing is not finite and positive, plus whatever the boundary walk refuses.