C# 点到直线的垂直距离

 private void btnShortLen_Click(object sender, EventArgs e)
        {
            System.Diagnostics.Stopwatch sw0 = new System.Diagnostics.Stopwatch();
            sw0.Start();

            int i = 0;
            while (i < 100000)
            {
                Point pi1 = new Point(0, 0);
                Point pst = new Point(0, 4);
                Point ped = new Point(4, 0);
                double dis = GetMinDistance(pst, ped, pi1);
                i++;
            }
            sw0.Stop();
            var s0 = sw0.ElapsedMilliseconds; //4  此方法省时

            System.Diagnostics.Stopwatch sw1 = new System.Diagnostics.Stopwatch();
            sw1.Start(); i = 0;
            while (i < 100000)
            {
                Vector3 point_a = new Vector3(0f, 0f, 1.0f);
                Vector3 point_b = new Vector3(0f, 4.0f, 1.0f);
                Vector3 point_c = new Vector3(4f, 0f, 1.0f);
                VectorCalculate vec_Calculate = new VectorCalculate(point_b, point_c, point_a);
                float res = vec_Calculate.DistanceCalculate();
                i++;
            }
            sw1.Stop();
            var s1 = sw1.ElapsedMilliseconds;  //10
        }
        /****点到直线的距离*** c#版本 
           * 过点（x1,y1）和点（x2,y2）的直线方程为：KX -Y + (x2y1 - x1y2)/(x2-x1) = 0
           * 设直线斜率为K = (y2-y1)/(x2-x1),C=(x2y1 - x1y2)/(x2-x1)
           * 点P(x0,y0)到直线AX + BY +C =0DE 距离为：d=|Ax0 + By0 + C|/sqrt(A*A + B*B)
           * 点（x3,y3）到经过点（x1,y1）和点（x2,y2）的直线的最短距离为：
           * distance = |K*x3 - y3 + C|/sqrt(K*K + 1)
           */
        public static double GetMinDistance(PointF pstart, PointF pend, PointF poxy)
        {
            double dis = 0;
            if (pstart.X == pend.X)
            {
                dis = Math.Abs(poxy.X - pstart.X);
                return dis;
            }
            double lineK = (pend.Y - pstart.Y) / (pend.X - pstart.X);
            double lineC = (pend.X * pstart.Y - pstart.X * pend.Y) / (pend.X - pstart.X);
            dis = Math.Abs(lineK * poxy.X - poxy.Y + lineC) / (Math.Sqrt(lineK * lineK + 1));
            return dis;
        }
    }
    class VectorCalculate
    {

        public VectorCalculate(Vector3 point_a, Vector3 point_b, Vector3 point_c)
        {
            _point_a = point_a;
            _point_b = point_b;
            _point_c = point_c;
        }
        public float DistanceCalculate()
        {
            Vector3 vec_ab = _point_b - _point_a;
            Vector3 vec_ac = _point_c - _point_a;
            float distance = 0.0f;
            Vector3 vec_Normalize = Vector3.Normalize(vec_ab);
            float projection_length = Vector3.Dot(vec_ac, vec_Normalize); //计算出投影向量的模
            Vector3 vec_Projection = Vector3.Multiply(projection_length, vec_Normalize); //计算出投影向量
            distance = Vector3.Distance(vec_ac, vec_Projection);
            return distance;
        }

        private Vector3 _point_a;
        private Vector3 _point_b;
        private Vector3 _point_c;
    }