//glwidget.h


#ifndef _GLWIDGET_H
#define _GLWIDGET_H

#include <QtOpenGL/QGLWidget>

class GLWidget : public QGLWidget {

    Q_OBJECT // must include this if you use Qt signals/slots

public:
    GLWidget(QWidget *parent = NULL);
    int op;
    int cirx, ciry;
protected:
    void initializeGL();
    void resizeGL(int w, int h);
    void paintGL();


};

#endif  /* _GLWIDGET_H */

//glwidget.cpp

#include <QtGui/QMouseEvent>
#include <QtOpenGL>
#include <GL/freeglut.h>
#include "glwidget.h"

GLWidget::GLWidget(QWidget *parent) : QGLWidget(parent) {
    setMouseTracking(true);
    op=0;
}

void GLWidget::initializeGL() {
    glDisable(GL_TEXTURE_2D);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_COLOR_MATERIAL);
    glEnable(GL_BLEND);
    glEnable(GL_POLYGON_SMOOTH);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glClearColor(0, 0, 0, 0);
}

void GLWidget::resizeGL(int w, int h) {
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, w, 0, h); // set origin to bottom left corner
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();



}

void GLWidget::paintGL() {
    glClear(GL_COLOR_BUFFER_BIT);



    glColor3f(0,1,0);
    glBegin(GL_QUADS);
    glVertex2f(450,450);
    glVertex2f(600,450);
    glVertex2f(600,600);
    glVertex2f(450,600);
    glEnd();
    swapBuffers();
}

//main.cpp


#include <QtGui/QApplication>
#include <QtOpenGL/QGLWidget>
#include "glwidget.h"

int main(int argc, char *argv[]) {

    QApplication app(argc, argv);

    GLWidget window;
    window.resize(1600,1200);
    window.show();

    return app.exec();
}