YLScsDrawing.Geometry.Vector.IsClockwise C# (CSharp) Method

        public static bool IsClockwise(PointF pt1, PointF pt2, PointF pt3)
        {
            Vector V21 = new Vector(pt2, pt1);
            Vector v23 = new Vector(pt2, pt3);
            return V21.CrossProduct(v23) < 0; // sin(angle pt1 pt2 pt3) > 0, 0<angle pt1 pt2 pt3 <180
        }