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It seems that the paintEvent method of the QGLWidget is called before initializeGL, so where am I supposed to put my openGL initialization code?

I'm putting it into the paintEvent method like this:

void MyGLWidget::paintEvent(...)
   makeCurrent();
   ..save modelview and projection matrices..
   // This is initialization code
   GLenum init = glewInit();
    if (GLEW_OK != init)
      /* Problem: glewInit failed, something is seriously wrong. */
      qWarning() << glewGetErrorString(init);
    // Dark blue background
    glClearColor(0.2f, 0.0f, 0.5f, 0.0f);
    // Enable depth test
    glEnable(GL_DEPTH_TEST);
   // End initialization code
   ... drawing code
   QPainter painter(this);
   ...overpainting..
I really don't like the idea of having my glew library initialization function called every time a paintEvent is raised... although that's working.
Any suggestion?
                If I call "updateGL" from paintEvent, and let initializeGL and paintGL do the work, for some reason the screen is rendered okay but then is immediately swapped entirely white. Why is that?
– Johnny Pauling
                Jul 18, 2012 at 19:52
Override initializeGL() function of QGLWidget. It is Created right for the purposes you want
From it's documentation:
  
This virtual function is called once before the first call to
  paintGL() or resizeGL(), and then once whenever the widget has been
  assigned a new QGLContext. Reimplement it in a subclass.
link to documentation: http://doc.qt.io/archives/qt-4.7/qglwidget.html#initializeGL
                as I said, it seems initializeGL is called AFTER paintEvent, so I can't draw in paintEvent without glew extensions and shaders set (which should be done, in my humble opinion, into initializeGL)
– Johnny Pauling
                Jul 18, 2012 at 17:25
                @JohnPell: sorry, I did not notice that. Are you sure it's called after paint event? Try to put break points in both functions and check which one is triggered first
– Andrew
                Jul 18, 2012 at 17:37
                I did that, that's why I wrote that initializeGL is called after paintEvent. It's weird but seems so
– Johnny Pauling
                Jul 18, 2012 at 17:46
                @JohnPell: have you tried putting breakpoints to see if paint is really called before initialize ?
– Andrew
                Jul 18, 2012 at 17:48
                yes, I tried with breakpoints, and it's not necessary to put breakpoints because if I put the initialization code into initializeGL and the normal drawing code in paintEvent, the scene crashes because initializeGL isn't called before paintEvent
– Johnny Pauling
                Jul 18, 2012 at 17:49
        
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