[Qt-interest] Performance issues with Graphics View Framework

[Enrico Ros]

Also note that:

 -  Painting performance changes a lot depending on that you have to paint. 
QPainter::fillRect() is faster than Painter::drawEllipse() (since the first 
can be accelerated in OpenGL, the other no).

 - Try to use different Qt Versions (later versions aften accelerate more 
painting commands and more efficiently on opengl)

 - Disable antialiasing in QPainter.

 - Make sure that the QGLWidget is constructed without the SampleBuffer 
support (look at QGLWidget doc, I don't have it here. SampleBuffers are 
OpenGL's way to do AntiAliasing).

 - run some OpenGL benchmarchs (like "glxgears" (should report > 2000 fps on 
your desktop)) to make sure OpenGL is accelerated and you're not using the 
software fallback

 - try to see if QPixmap are faster than QImages or vice-versa, and switch to 
that implementation.

 - Note that Poulsbo is known to suck more that anything else [1]. Desktop 
performance should be better indeed.

Ciao,
Enrico

[1] http://www.phoronix.com/scan.php?page=news_item&px=NzAyOQ


On Monday 20 July 2009 13:04:33 Alexis Menard wrote:
> And sometimes it is faster to set the viewport update mode to
> FullUpdate in OpenGl.
>
> On Jul 20, 2009, at 12:48, Srdjan Todorovic wrote:
> > Hi,
> >
> > On 20/07/2009, Simone Artesino <mlist.sa at gmail.com> wrote:
> >> I've got a terrible performance degradation when switch Viewport from
> >> QWidget to QGLWidget. The same qt code (no opengl calls in it) that
> >> make a
> >> simple animation, it runs 10 times slower (from 40 fps to 4 fps).
> >> On the
> >
> > Are you running OpenGL in software-only mode?
> > I know from playing games in Linux, that if you do not have hardware
> > accelerated OpenGL, things are very very slow.
> >
> > Hope that helps,
> > Srdjan
> > _______________________________________________
> > Qt-interest mailing list
> > Qt-interest at trolltech.com
> > http://lists.trolltech.com/mailman/listinfo/qt-interest
>
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