private bool AngleSign() { Point a = (_head.Next - _head); Point b = (_tail - _head); return(FP.Atan2(a.Cross(b), a.Dot(b)) >= 0); }
private FP Angle(Point p) { Point a = (p.Next - p); Point b = (p.Prev - p); return(FP.Atan2(a.Cross(b), a.Dot(b))); }