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class MyOGL : public QGLWidget
{
protected:
    virtual void initializeGL();
    virtual void resizeGL(int nWidth,int nHeight);
    virtual void paintGL();
public:
    MyOGL(QWidget *parent = 0);
};

MyOGL::MyOGL(QWidget *parent) : QGLWidget(parent)
{

}

void MyOGL::initializeGL()
{
    qglClearColor(Qt::black);
    glViewport(0,0,200,200);
}
void MyOGL::resizeGL(int nWidth,int nHeight)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glViewport(0,0,(GLint)nWidth,(GLint) nHeight);
    glOrtho (0,100,100,0,-1,-1);

}

 void MyOGL::paintGL()
{
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

     glBegin(GL_QUADS);

         glColor3f(1,0,0);
         glVertex2f(0,0);

         glColor3f(1,0,0);
         glVertex2f(0,200);

         glColor3f(1,0,0);
         glVertex2f(100,200);

         glColor3f(1,0,0);
         glVertex2f(100,0);


     glEnd();


}

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

    MyOGL test;
    test.resize(200,200);
    test.show();

    return a.exec();
}

void glOrtho(
GLdouble left, 
GLdouble right, 
GLdouble bottom, 
GLdouble top, 
GLdouble near, 
GLdouble far 
);

glOrtho(0, nWidth, 0, nHeight, -1, 1 );