旋转后点的坐标

二维空间中，给定一个点与一个角度，求其绕另一个点旋转后的坐标。

公式如下，（x1，y1）为要转的点，（x2,y2）为中心点，

x=(x1-x2)cosθ-(y1-y2)sinθ+x2

y=(y1-y2)cosθ+(x1-x2)sinθ+y2

c++实现

void rotate(Point src, Point & dst, float angle)
{
       float theta = angle / 180 * 3.1415926;
       int x1,x2,y1,y2;
       x1 = src.x;  
       x2 = dst.x;
       y1 = src.y; 
       y2 = dst.y;
       dst.x = (x1 - x2) * cos(theta) - (y1 -y2) * sin(theta) + x2;
       dst.y = (y1 - y2) * cos(theta) + (x1 - x2) * sin(theta) + y2;

}

void Location_Rotation(Point2f* Src_Location, Point2f* Dst_Location, float angle, Mat& input)
{
	if (angle != 0)
	{
		angle *= CV_PI / 180;

		Point2f center((float)input.cols*0.5, (float)input.rows*0.5);

		float alpha = cos(angle);
		float beta = sin(angle);

		Mat M(2, 3, CV_32F);

		float* m = (float*)M.data;

		m[0] = alpha;
		m[1] = beta;
		m[2] = (1 - alpha)*center.x - beta*center.y;
		m[3] = -beta;
		m[4] = alpha;
		m[5] = beta*center.x + (1 - alpha)*center.y;

		
		Point2f source = Src_Location[0];

		Dst_Location[0].x = source.x*m[0] + source.y*m[1] + m[2];
		Dst_Location[0].y = source.x*m[3] + source.y*m[4] + m[5];
		
	}
	else
	{
		
		Dst_Location[0] = Src_Location[0];
		
	}
}