/// <summary>
/// Bond a triangle to a subsegment.
/// </summary>
internal void SegBond(ref Osub os)
{
tri.subsegs[orient] = os;
os.seg.triangles[os.orient] = this;
}
/// <summary>
/// Finds a subsegment abutting a triangle.
/// </summary>
internal void Pivot(ref Osub os)
{
os = tri.subsegs[orient];
}