static public PointF[,] BezierCut(PointF[] points, float t){
            PointF[,] result = new PointF[2, points.Length];
            
            //stでくぎられる点を見つける
            //分割前の P0, Pn が分割後の L0, Rn になる
            result[0,0] = points[0];
            result[1,points.Length-1] = points[points.Length - 1];

            PointF[] prev = points;
            for (int i = 1; i < points.Length; i++)
            {
                PointF[] tmp = new PointF[points.Length - i];
                for (int j = 0; j < points.Length - i; j++)
                {
                    //tmp[j] - tmp[j+1] の間を st で区切る
                    tmp[j].X = prev[j].X + (prev[j + 1].X - prev[j].X) * t;
                    tmp[j].Y = prev[j].Y + (prev[j + 1].Y - prev[j].Y) * t;
                }
                result[0,i].X = tmp[0].X;
                result[0,i].Y = tmp[0].Y;
                result[1,points.Length - i - 1].X = tmp[tmp.Length - 1].X;
                result[1,points.Length - i - 1].Y = tmp[tmp.Length - 1].Y;

                prev = tmp; //算出したものを保持
            }

            return result;
        }