C#實現計算一個點圍繞另一個點旋轉指定弧度后坐標值的方法

2020-01-24 01:32:48

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本文實例講述了C#實現計算一個點圍繞另一個點旋轉指定弧度后坐標值的方法。分享給大家供大家參考。具體如下：

1.示例圖

P(x1,y1)以點A(a,b)為圓心，旋轉弧度為θ，求旋轉后點Q(x2,y2)的坐標

2.實現方法

先將坐標平移，計算點(x1-a,y1-b)圍繞原點旋轉后的坐標，再將坐標軸平移到原狀態

/// <summary>/// 結構：表示一個點/// </summary>struct Point{ //橫、縱坐標 public double x, y; //構造函數 public Point(double x, double y) {  this.x = x;  this.y = y; } //該點到指定點pTarget的距離 public double DistanceTo(Point p) {  return Math.Sqrt((p.x - x) * (p.x - x) + (p.y - y) * (p.y - y)); } //重寫ToString方法 public override string ToString() {  return string.Concat("Point (",   this.x.ToString("#0.000"), ',',   this.y.ToString("#0.000"), ')'); }}/// <summary>/// 計算點P(x,y)與X軸正方向的夾角/// </summary>/// <param name="x">橫坐標</param>/// <param name="y">縱坐標</param>/// <returns>夾角弧度</returns>private static double radPOX(double x,double y){ //P在(0,0)的情況 if (x == 0 && y == 0) return 0; //P在四個坐標軸上的情況：x正、x負、y正、y負 if (y == 0 && x > 0) return 0; if (y == 0 && x < 0) return Math.PI; if (x == 0 && y > 0) return Math.PI / 2; if (x == 0 && y < 0) return Math.PI / 2 * 3; //點在第一、二、三、四象限時的情況 if (x > 0 && y > 0) return Math.Atan(y / x); if (x < 0 && y > 0) return Math.PI - Math.Atan(y / -x); if (x < 0 && y < 0) return Math.PI + Math.Atan(-y / -x); if (x > 0 && y < 0) return Math.PI * 2 - Math.Atan(-y / x); return 0;}/// <summary>/// 返回點P圍繞點A旋轉弧度rad后的坐標/// </summary>/// <param name="P">待旋轉點坐標</param>/// <param name="A">旋轉中心坐標</param>/// <param name="rad">旋轉弧度</param>/// <param name="isClockwise">true:順時針/false:逆時針</param>/// <returns>旋轉后坐標</returns>private static Point RotatePoint(Point P, Point A,  double rad, bool isClockwise = true){ //點Temp1 Point Temp1 = new Point(P.x - A.x, P.y - A.y); //點Temp1到原點的長度 double lenO2Temp1 = Temp1.DistanceTo(new Point(0, 0)); //∠T1OX弧度 double angT1OX = radPOX(Temp1.x, Temp1.y); //∠T2OX弧度（T2為T1以O為圓心旋轉弧度rad） double angT2OX = angT1OX - (isClockwise ? 1 : -1) * rad; //點Temp2 Point Temp2 = new Point(  lenO2Temp1 * Math.Cos(angT2OX),  lenO2Temp1 * Math.Sin(angT2OX)); //點Q return new Point(Temp2.x + A.x, Temp2.y + A.y);}

3.Main函數調用

static void Main(string[] args){ //求兩點間長度 Point A = new Point(0, 0); Point B = new Point(3, 4); Console.WriteLine("Length of AB: " + A.DistanceTo(B)); Point P = new Point(5, -5); Console.WriteLine(P.ToString() + '/n'); //繞原點(0,0)逆時針旋轉 Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 9, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 10, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 11, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 12, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 13, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 14, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 15, false)); Console.WriteLine(RotatePoint(P, new Point(0, 0), Math.PI / 4 * 16, false)); Console.WriteLine(); //繞點(2.5,2.5)順時針旋轉 Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 1)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 2)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 3)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 4)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 5)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 6)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 7)); Console.WriteLine(RotatePoint(P, new Point(2.5, 2.5), Math.PI / 4 * 8)); Console.ReadLine();}

4.運行結果：