用OpenCV计算到红点的距离

我是openCV的新手。刚刚设法安装并将其设置为Visual2013。我用笔记本电脑相机的实时流示例对其进行了测试。现在，我想通过网络摄像头与将位于屏幕中间的红色激光点（Live_stream）计算距离。告诉我从哪里开始？我知道我必须从屏幕中间找到R（红色）像素，但我不知道该怎么做以及可以使用什么功能。请问吗？来自网络摄像头的实时流如下所示：

   #include "opencv2/highgui/highgui.hpp"
   #include <opencv2/objdetect/objdetect.hpp>
   #include <opencv2/imgproc/imgproc.hpp>
   #include <iostream>
   #include <vector>
   #include <stdio.h>
 int main()
 {
 //Data Structure to store cam.
 CvCapture* cap=cvCreateCameraCapture(0);
 //Image variable to store frame
 IplImage* frame;
 //Window to show livefeed
 cvNamedWindow("Imagine Live",CV_WINDOW_AUTOSIZE);
while(1)
{
//Load the next frame
frame=cvQueryFrame(cap);
//If frame is not loaded break from the loop
if(!frame)
    printf("nno");;
//Show the present frame
cvShowImage("Imagine Live",frame);
//Escape Sequence
char c=cvWaitKey(33);
//If the key pressed by user is Esc(ASCII is 27) then break out of the loop
if(c==27)
   break;
}
//CleanUp
cvReleaseCapture(&cap);
cvDestroyAllWindows();
}