Using QPainter over OpenGL in QGLWidget when using shaders

Question

Many of you Qt (4.6 specifically) users will be familiar with the Overpainting example supplied in the OpenGL tutorials, I\'m trying to do something very similar but using s

Answer 1

Call beginNativePainting() before making OpenGL calls. A glPush/Pop of the OpenGL state may also be necessary. Try something like the following:

QPainter p( this );
p.beginNativePainting();

// Maybe necessary
glPushAttrib(GL_ALL_ATTRIB_BITS);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glMatrixMode(GL_MODELVIEW);
glPushMatrix();

// Put OpenGL code here

// Necessary if used glPush-es above
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glPopAttrib();

p.endNativePainting();

p.fillRect( 10, 10, 100, 100,
        QColor( 255, 0, 0 ) );