[Development] OpenGL drivers

Robert Knight robertknight at gmail.com
Fri Nov 29 15:20:48 CET 2013

> As many of you might already have noticed, OpenGL drivers are not always working as well as would like.

To what extent does this apply to different platforms and vendors? Is
Qt doing anything different from other GL apps on the same platform or
are they facing the same issues?

On 29 November 2013 12:27, Sletta Gunnar <Gunnar.Sletta at digia.com> wrote:
> Hi,
> As many of you might already have noticed, OpenGL drivers are not always working as well as would like. This has always been a problem, but since Qt Creator 3.0 is using Qt Quick 2.0 and Qt Quick 2.0 is also being used in more and more places, the problem is becoming more mainstream. We are aware of several issues and patched Qt to tackle them, but we expect we will need more. To figure out what needs to be done, we need a broader picture.
> Long term, the solution for Qt might be that we bundle a software GL implementation (llvmpipe for instance) and switch to that if a driver is too problematic for us. Hopefully, we can get by with applying workarounds in Qt though.
> So, I'm asking that if you encounter issues with flickering, crashes, bad rendering and similar, help us track which things are problematic by filing a bugreport on bugreports.qt-project.org and use the label "driverissue" in the task. Please  include OS, windowing system, graphics hardware and driver version. And since most of the workarounds have been applied to Qt 5.2, do test against the 5.2 RC1 or later.
> Some other things that might help while identifying the problem is:
> - Does upgrading driver or installing latest vendor supplied driver help?
> - QSG_RENDER_LOOP=basic -> switch Qt Quick to use the GUI thread for rendering
> - QSG_INFO=1 -> make Qt Quick output SG and GL information.
> - LIBGL_ALWAYS_SOFTWARE=1 -> for Linux/Mesa based only, forces use of software Mesa rendering
> - How does other GL applications in the system fare and what about Qt's OpenGL examples?
> - vsynced or not?
> thanks,
> Gunnar
> Please don't reply to this mail to report issues :)
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