Help me to track the mistake for measuring angles in opencv

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Hi all,

Here i have put my code which is in c++. I am new in OpenCV. So Please Help me.

I found this code in Python and try to convert it in C++ and thanks to chris loughnane who is original author of this thing.click here for more detail.

enter code here
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include<opencv/cv.h>
#include <iostream>
#include <math.h>
#include <string.h>

using namespace cv;
using namespace std;

int main()
{
    CvCapture *capture  = cvCaptureFromCAM(0);
    cvNamedWindow("Target", 1);
    cvNamedWindow("Threshold1",1);
    cvNamedWindow("Threshold2",1);
    cvNamedWindow("hsv",1);

    //#initiate font
    CvFont *font;
    cvInitFont(font,CV_FONT_HERSHEY_SIMPLEX, 1, 1, 0, 3, 8);
    //instantiate images
    IplImage* hsv_img = cvCreateImage(cvGetSize(cvQueryFrame(capture)),8,3);
    IplImage* threshold_img1 = cvCreateImage(cvGetSize(hsv_img),8,1);
    IplImage* threshold_img1a = cvCreateImage(cvGetSize(hsv_img),8,1);
    IplImage* threshold_img2 = cvCreateImage(cvGetSize(hsv_img),8,1);

    int i=0;
    CvCapture * writer;  // = cvCreateVideoWriter("angle_tracking.avi",CV_FOURCC('M','J','P','G'),30,cvGetSize(hsv_img),1);
    cvCreateVideoWriter("d:/1/1.avi",CV_FOURCC('M','J','P','G'),30,cvGetSize(hsv_img),1);

    while (true)
    {
       // capture the image from the cam
        IplImage *img = cvQueryFrame(capture);

        //convert the image to HSV
        cvCvtColor(img,hsv_img,CV_BGR2HSV);

        //threshold the image to isolate two colors

        cvInRangeS(hsv_img,cvScalar(165,145,100),cvScalar(250,210,160),threshold_img1);     //#red
        cvInRangeS(hsv_img,cvScalar(0,145,100),cvScalar(10,210,160),threshold_img1a);       //#red again
        cvAdd(threshold_img1,threshold_img1a,threshold_img1);                               //#this is combining the two limits for red
        cvInRangeS(hsv_img,cvScalar(105,180,40),cvScalar(120,260,100),threshold_img2);      //#blue


      //  #determine the moments of the two objects
        CvMat stub;
        CvMat *threshold_img1 = cvGetMat(threshold_img1,&stub);
        CvMat *threshold_img2 = cvGetMat(threshold_img2,&stub);

        CvMoments *moments1,*moments2;
        cvMoments(threshold_img1,moments1);
        cvMoments(threshold_img2,moments2);

        double area1 = cvGetCentralMoment(moments1,0,0);
        double area2 = cvGetCentralMoment(moments2,0,0);

        //initialize x and y
        float x1,y1,x2,y2=(1,2,3,4);
        float coord_list=(x1,y1,x2,y2);

        for (i=1; i < 4; i++)
        {
        int x=0;
        //there can be noise in the video so ignore objects with small areas

        if (area1 >200000)
        {
            //x and y coordinates of the center of the object is found by dividing the 1,0 and 0,1 moments by the area
            x1=int(cvGetSpatialMoment(moments1,1,0)/area1);
            y1=int(cvGetSpatialMoment(moments1,0,1)/area1);

            //draw circle
            cvCircle(img,cvPoint(x1,y1),2,CV_RGB(0,255,0),20);

            //write x and y position
            cvPutText(img,char (str(x1)+","+str(y1)),cvPoint(x1,y1+20),font, CV_RGB(255,0,0)); //#Draw the text
        }

        if (area2 >100000)
        {
            //x and y coordinates of the center of the object is found by dividing the 1,0 and 0,1 moments by the area
            x2=int(cvGetSpatialMoment(moments2,1,0)/area2);
            y2=int(cvGetSpatialMoment(moments2,0,1)/area2);

            //draw circle
            cvCircle(img,cvPoint(x2,y2),2,CV_RGB(0,255,0),20);

            //cvPutText(img,str(x2)+","+str(y2),cvPoint(x2,y2+20),font, cvScalar(255)); //#Draw the text
            cvLine(img,cvPoint(x1,y1),cvPoint(x2,y2),CV_RGB(0,255,0),4,CV_AA);
            //#draw ...