public static SKPath ToSKPath(DGraph2 g, Func <Vector2d, SKPoint> mapF)
        {
            SKPath p = new SKPath();

            foreach (Index3i edge in g.Edges())
            {
                Vector2d a = g.GetVertex(edge.a);
                Vector2d b = g.GetVertex(edge.b);
                p.MoveTo(mapF(a));
                p.LineTo(mapF(b));
                p.Close();
            }

            return(p);
        }