任意多点按某一方向排序

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List<PointF> SortPoints(PointF[] points) {   List<PointF> result = new List<PointF>();   PointF center = GetGravityPoint(points.ToList());   PointF x = new PointF(center.X+1, center.Y);   PointF OX = new PointF(1,0);   double OX_len = 1;     List<double>  angle = new List<double>();     foreach (PointF point in points)   {     PointF tmpO = new PointF(point.X-center.X,point.Y-center.Y);     double tmp_len = Math.Sqrt((point.X - center.X)*(point.X - center.X)+(point.Y - center.Y)*(point.Y - center.Y));     angle.Add(Math.Asin((tmpO.X)/tmp_len));   }   List<double>  tmpAngle = new List<double>(angle);   tmpAngle.Sort();   List<double> doubles = new List<double>();   for(int i = 0;i< tmpAngle.Count;i++)   {     double tmp = tmpAngle[i];     int v = angle.FindIndex(item => item.Equals(tmp));     result.Add(points[v]);   }         return result; } private PointF GetGravityPoint(List<PointF> lstPol) {     double n, i;   double x1, y1, x2, y2, x3, y3;   double sum_x = 0, sum_y = 0, sum_s = 0;     x1 = lstPol[0].X;   y1 = lstPol[0].Y;   x2 = lstPol[1].X;   y2 = lstPol[1].Y;     n = lstPol.Count;   int k = 2;   for (i = 1; i <= n - 2; i++)   {     x3 = lstPol[k].X;     y3 = lstPol[k].Y;     double s = ((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1)) / 2.0;     sum_x += (x1 + x2 + x3) * s;     sum_y += (y1 + y2 + y3) * s;     sum_s += s;     x2 = x3;     y2 = y3;     k++;   }   PointF center = PointF.Empty;   center.X = Convert.ToSingle(sum_x / sum_s / 3.0);   center.Y = Convert.ToSingle(sum_y / sum_s / 3.0);   //MessageBox.Show("("+center.X.ToString()+","+center.Y.ToString()+")");   return center; }