Function open_chart_ring 

pub fn open_chart_ring(
    model: &Model,
    face: &Shape,
    wire: &Shape,
    largest: bool,
    deflection: Deflection,
    tol: Tolerances,
) -> OgeomResult<Option<Vec<Point2>>>

One wire’s trimming ring on a face whose chart neither repeats nor closes on itself, as face_boundary_in_chart draws it among the face’s other rings; None where the wire leaves no ring there.

On such a chart each ring is drawn from its own wire alone, so a caller asking about a few holes of a face with hundreds draws only those. The one ring drawn differently is a slit (a wire walking out and back along the same vertices, thinner than a micron), which face_boundary drops unless it is the face’s largest ring: largest says whether this wire’s ring is that one.

Errors

As face_boundary, and OgeomError::Construction where the face’s surface repeats or closes in either chart direction.