[Qt-interest] disappearing widgets in QGraphicsScene

[Samuel Rødal]

Yifei Li wrote:
> Hi,
> 
> I kinda fixed the problem by saving and then restoring modelview and projection matrices.
> 
> However, the problem still persists when I enable multiple viewports. I tried glPushAttrib/glPopAttrib, but that did not help.
> 
> Here is what I tried:
> 
> void drawBackground(QPainter*, const QRectF&)
> {
>    glClearColor(...)
>    glClear(...);          // clear depth and color buffer
> 
>    glPushAttrib(GL_ALL_ATTRIB_BITS);
>    glMatrixMode(GL_PROJECTION);
>    glPushMatrix();
>    glMatrixMode(GL_MODELVIEW);
>    glPushMatrix();
> 
>    // render stuff in the 1st viewport
>    ...
>    // render stuff in the 2nd viewport
>    ...
> 
>    glMatrixMode(GL_PROJECTION);
>    glPopMatrix();
>    glMatrixMode(GL_MODELVIEW);
>    glPopMatrix();
>    glPopAttrib();
> }
> 
> Please help me out. Thanks
> 
> Yifei

If you're using Qt 4.6 you can try surrounding the OpenGL code with 
painter->beginNativePainting() and painter->endNativePainting(). That 
should lead to better synchronization when intermixing QPainter and raw 
OpenGL code (even if you don't use the QPainter in drawBackground it's 
used by QGraphicsView).

--
Samuel