Drawing Shapes (Line, Circle, ..., etc) in C++

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc.hpp> // drawing shapes
#include <iostream>


int main( int argc, char** argv )
{
    // First create a black image. 
    cv::Mat image(500,500, CV_8UC3, cv::Scalar(0,0,0));

    // Check if the image is created successfully. 
    if( !image.data ){
        std::cout <<  "Could not open or find the image" << std::endl ;
        exit(EXIT_FAILURE);
    }
    
    
    //####################(  Draw Line  )##########################
    cv::Point p1(100,100), p2(200,100);
    cv::Scalar colorLine(0,255,0); // Green
    int thicknessLine = 2;
    
    cv::line(image, p1, p2, colorLine, thicknessLine);
    
    //####################(  Draw Circle  )#########################
    // unfilled circle
    cv::Point centerCircle1(250,250);
    int radiusCircle = 30;
    cv::Scalar colorCircle1(0,0,255);
    int thicknessCircle1 = 2;
    
    cv::circle(image, centerCircle1, radiusCircle, colorCircle1, thicknessCircle1);
    
    // filled circle
    cv::Point centerCircle2(400,100);
    cv::Scalar colorCircle2(0,100,0);
    
    cv::circle(image, centerCircle2, radiusCircle, colorCircle2, CV_FILLED);
    
    //####################(  Draw Rectangle  )#######################
    // unfilled 
    cv::Point p3(400,400), p4(450,450);
    cv::Scalar colorRectangle1(0,0,255);
    int thicknessRectangle1 = 3;
    
    cv::rectangle(image, p3, p4, colorRectangle1,thicknessRectangle1);
    
    //   filled
    cv::Point p5(100,400), p6(150,450);
    cv::Scalar colorRectangle2(255,0,255);
     
    cv::rectangle(image, p5, p6, colorRectangle2, CV_FILLED);
    
    
    //#################( Draw Shapes on Image )######################
    cv::namedWindow( "Display window", cv::WINDOW_AUTOSIZE );
    cv::imshow( "Display window", image );                  

    cv::waitKey(0);   
    
    
    return 0;
}

g++ main2.cpp -o main `pkg-config --cflags --libs opencv`