Struct HalfedgeTriangulation 

pub struct HalfedgeTriangulation {
    pub halfedges: Vec<Halfedge>,
    pub contour_end: usize,
}

Triangulation result represented directly as halfedges, ported from HalfedgeTriangulation in C++ polygon_internal.h.

halfedges[0..contour_end] are the exterior contour halfedges (the input edges reversed, so their end_vert holds the original idx of the edge’s start point). halfedges[contour_end..] hold three halfedges per output triangle. All vertex fields are original idx values.

Pairing happens incrementally with a LIFO multimap keyed on (start, end), so duplicate vertex pairs (from degenerate/overlapping polygons) still pair one-to-one within the triangulation. This is what Face2Tri relies on to keep boolean results manifold on exactly-coplanar faces — re-deriving pairs from vertex positions after the fact cannot distinguish duplicates.

Fields

halfedges: Vec<Halfedge>

contour_end: usize

Implementations

impl HalfedgeTriangulation

pub fn num_tri(&self) -> usize