#include "opencv2/highgui/highgui.hpp"

#include "opencv2/imgproc/imgproc.hpp"

#include <iostream>

using namespace cv;

using namespace std;

static void help()

{

    cout << "\nThis program demonstrates line finding with the Hough transform.\n"

            "Usage:\n"

            "./houghlines <image_name>, Default is pic1.png\n" << endl;

}

int main(int argc, char** argv)

{

    const char* filename = argc >= 2 ? argv[1] : "pic1.png";

    Mat src = imread(filename, 0);

    if(src.empty())

    {

        help();

        cout << "can not open " << filename << endl;

        return -1;

    }

    Mat dst, cdst;

    Canny(src, dst, 50, 200, 3);

    cvtColor(dst, cdst, CV_GRAY2BGR);

#if 1

    vector<Vec2f> lines;

    HoughLines(dst, lines, 1, CV_PI/180, 100, 0, 0 );

    for( size_t i = 0; i < lines.size(); i++ )

    {

        float rho = lines[i][0], theta = lines[i][1];

        Point pt1, pt2;

        double a = cos(theta), b = sin(theta);

        double x0 = a*rho, y0 = b*rho;

        pt1.x = cvRound(x0 + 1000*(-b));

        pt1.y = cvRound(y0 + 1000*(a));

        pt2.x = cvRound(x0 - 1000*(-b));

        pt2.y = cvRound(y0 - 1000*(a));

        line( cdst, pt1, pt2, Scalar(0,0,255), 3, CV_AA);

    }

#else

    vector<Vec4i> lines;

    HoughLinesP(dst, lines, 1, CV_PI/180, 50, 50, 10 );

    for( size_t i = 0; i < lines.size(); i++ )

    {

        Vec4i l = lines[i];

        line( cdst, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(0,0,255), 3, CV_AA);

    }

#endif

    imshow("source", src);

    imshow("detected lines", cdst);

    waitKey();

    return 0;

}