[C#] 求解點到點/點到線距離

whitefox

以下方法都是建立在笛卡爾座標系上使用

1. /// <summary>
   
2. /// 點到點距離
   
3. /// </summary>
   
4. /// <param name="p1"></param>
   
5. /// <param name="p2"></param>
   
6. /// <returns></returns>
   
7. public static double GetDistancePP(Point p1, Point p2)
   
8. {
   
9.     return Math.Sqrt(((p1.X - p2.X) * (p1.X - p2.X)) + ((p1.Y - p2.Y) * (p1.Y - p2.Y)));
   
10. }

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直線算是兩個點的集合

1. /// <summary>
   
2. /// 點到直線距離
   
3. /// </summary>
   
4. /// <param name="p0"></param>
   
5. /// <param name="p1"></param>
   
6. /// <param name="p2"></param>
   
7. /// <returns></returns>
   
8. public static double GetDistancePL(Point p0, Point p1, Point p2)
   
9. {
   
10.     double dist = 0;
    
11.     double x1 = p1.X;
    
12.     double y1 = p1.Y;
    
13.     double x2 = p2.X;
    
14.     double y2 = p2.Y;
    
15.     // 垂直狀況
    
16.     if (Math.Abs(x1 - x2) < 1e-6)
    
17.     {
    
18.         dist = Math.Abs(p0.X - x1);
    
19.     }
    
20.     else
    
21.     {
    
22.         // 根據點到直線距離公式計算
    
23.         // 計算斜率和截距
    
24.         double k = (y2 - y1) / (x2 - x1);
    
25.         double b = (x2 * y1 - x1 * y2) / (x2 - x1);
    
26.         dist = Math.Abs(k * p0.X - p0.Y + b) / Math.Sqrt(k * k + 1);
    
27. 
    
28.         // 根據海龍公式(希羅公式)計算
    
29.         // double lenP1P2 = GetDistancePP(p1, p2);
    
30.         // double lenP0P1 = GetDistancePP(p0, p1);
    
31.         // double lenP0P2 = GetDistancePP(p0, p2);
    
32.         // double len = 0.5 * (lenP0P1 + lenP0P2 + lenP1P2);
    
33.         // double area = Math.Sqrt(len * (len - lenP0P1) * (len - lenP0P2) * (len - lenP1P2));
    
34.         // dist = 2 * area / lenP1P2;
    
35.     }
    
36.     return dist;
    
37. }

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