In our main function we instantiate this class and set the QGraphicsView parameters that are needed in our case. First of all the viewport needs to be a QGLWidget in order to do OpenGL rendering in our graphics scene. We use the SampleBuffers format specifier to enable multisample anti-aliasing in our rendering code.

    int main(int argc, char **argv)
    {
        QApplication app(argc, argv);

        GraphicsView view;
        view.setViewport(new QGLWidget(
            QGLFormat(QGL::SampleBuffers)));
        view.setViewportUpdateMode(
            QGraphicsView::FullViewportUpdate);
        view.setScene(new OpenGLScene);
        view.show();

        view.resize(1024, 768);
        return app.exec();
    }
Next, we set the viewport update mode of the QGraphicsView to FullViewportUpdate as a QGLWidget cannot perform partial updates. Thus, we need to redraw everything whenever a part of the scene changes. We set as the scene an instance of our OpenGLScene class, a subclass of QGraphicsScene, and resize the view to a decent size.