Function belted_wire 

pub fn belted_wire(
    model: &mut Model,
    surface: SurfaceId,
    wires: &[Shape],
    tol: Tolerances,
) -> OgeomResult<Option<Shape>>

The one wire a face on a B-spline closed round in u takes when its file bounds it by rings alone and writes no seam: each ring runs the whole period along the chart, from one end column to the other, and without a seam no ring meets another, so the boundary encloses nothing in the chart. The seam is the surface’s own column at the period’s join, exact (the iso-curve the control columns trace), from where one ring’s walk ends to where the next begins; walked up one end column and back down the other, it closes the two rings into one loop. A single ring opposite a row the surface collapses to a point (a dome’s pole) takes the seam to that point and back, and the pole’s run across the chart is laid by closed_at_poles.

None where the face is not that shape: another surface, one closed the other way or periodic, a wire of more than one edge, or a ring whose image does not run end column to end column along one row.

Errors

OgeomError::Dangling if the surface, an edge or a pcurve is not in this model.