void SplitSegment(Segment2D s)
{
Vertex2D a = s.a, b = s.b;
var mv = new Vertex2D(s.Midpoint());
// add mv to V
// the index is between a and b.
var idxA = V.IndexOf(a);
var idxB = V.IndexOf(b);
if (Mathf.Abs(idxA - idxB) == 1)
{
var idx = (idxA > idxB) ? idxA : idxB;
V.Insert(idx, mv);
}
else
{
V.Add(mv);
}
UpdateTriangulation(mv.Coordinate);
// Add two halves to S
var sidx = S.IndexOf(s);
S.RemoveAt(sidx);
S.Add(new Segment2D(s.a, mv));
S.Add(new Segment2D(mv, s.b));
}
bool ExternalPSLG(Segment2D s)
{
return(ExternalPSLG(s.Midpoint()));
}