[Development] OpenGL Issues in Qt5.7

[Kai Koehne]

> -----Original Message-----
> From: Liu, Jeff (SRDC SW) [mailto:Jeff1.Liu at amd.com]
> Sent: Wednesday, October 26, 2016 7:09 AM
> To: gunnar.sletta at jollamobile.com; gunnar at sletta.org; Liang Qi
> <Liang.Qi at qt.io>; Kai Koehne <Kai.Koehne at qt.io>; development at qt-
> project.org
> Subject: RE: OpenGL Issues in Qt5.7
> 
> 
> 
> Spread to Qt mail-list to ask for help.
> 
> 
> 
> From: Liu, Jeff (SRDC SW)
> Sent: Tuesday, October 25, 2016 2:26 PM
> To: 'gunnar.sletta at jollamobile.com'; 'gunnar at sletta.org'; 'liang.qi at qt.io';
> 'kai.koehne at qt.io'
> Subject: OpenGL Issues in Qt5.7
> 
> 
> 
> Hi Sletta, Qi and Koehne,

Hi Jeff!

> This is Jeff from AMD, recently a customer reports a game issue with AMD
> cards, but the game runs well on Nvidia card, after some debug, I find out
> that the issues are caused by Qt libraries, when Qt programs with OpenGL
> API, it doesn’t follow the OpenGL programming specification strictly, so it will
> report errors on AMD platform.
> 
> Now we find out the two following issues, both issues come from Qt paint
> engine.
> 
> 1.       QTBUG-56234 - OpenGL glVertexAttribArray API usage error in
> Qt5Guid.dll
> 
> I submit a ticket to address this issue, and this issue is assigned to Sletta, but
> it seems no one starts to work on it, the usage of glVertexAttribArray API is
> wrong, it is still used in the old way (OpenGL 3.0), but it apparently violate the
> latest OpenGL specification (OpenGL 4.1)

Liang already commented on this one. Laszlo (the new assignee) probably
has a better idea about this, too.

> 2.       I don’t submit the ticket for the second issue yet,  Qt paint engine uses
> GL_RED to upload the texture, so based on the spec, the texture will be
> (GL_RED value, 0,0,1), but in pixel shader, it uses src * mask.a, which is a
> constant 0 value in AMD platform, if changed to src * mask.r, then everything
> will be correct, I will submit a ticket to address it later.

Feel free to report this, too.

> I don’t know what’s the right way to report and fix Qt issues, there may be
> more issues later in the game, so I write an email to you guys (I find your
> emails from code.qt.io), please tell me what should I do to co-work with you
> and make these issues fixed.

Reporting them on bugreports.qt.io is certainly a good start :) If you're a
commercial customer you should also go through Qt Support - often enough
the support team can help directly, or escalate things.

Regards

Kai