Template matching in webcam

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Hello there, i have a question.

i have a program that does simple template matching. My question is, i want to make the source from my webcam and the result is showed on my webcam. Here's my code

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

int main() 
{
    cv::Mat ref = cv::imread("reference.png");
    cv::Mat tpl = cv::imread("template.png");
    if (ref.empty() || tpl.empty())
        return -1;

    cv::Mat gref, gtpl;
    cv::cvtColor(ref, gref, CV_BGR2GRAY);
    cv::cvtColor(tpl, gtpl, CV_BGR2GRAY);

    cv::Mat res(ref.rows-tpl.rows+1, ref.cols-tpl.cols+1, CV_32FC1);
    cv::matchTemplate(gref, gtpl, res, CV_TM_CCOEFF_NORMED);
    cv::threshold(res, res, 0.8, 1., CV_THRESH_TOZERO);

    while (true) 
    {
        double minval, maxval, threshold = 0.8;
        cv::Point minloc, maxloc;
        cv::minMaxLoc(res, &minval, &maxval, &minloc, &maxloc);

        if (maxval >= threshold)
        {
            cv::rectangle(
                ref, 
                maxloc, 
                cv::Point(maxloc.x + tpl.cols, maxloc.y + tpl.rows), 
                CV_RGB(0,255,0), 2
            );
            cv::floodFill(res, maxloc, cv::Scalar(0), 0, cv::Scalar(.1), cv::Scalar(1.));
        }
        else
            break;
    }

    cv::imshow("reference", ref);
    cv::waitKey();
    return 0;
}

Thank you for your attention. I wait for any of your response.