[Interest] OpenGL Issues in Qt5.7

[Liu, Jeff (SRDC SW)]

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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,

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)

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.

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.

Look forward to your reply, thanks for your time!


Thanks
Jeff Liu
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