[Interest] Problem with float texture rendering in QOpenGLWidget on Ivy Bridge/Haswell Intel GPUs on Windows

Viktor Engelmann viktor.engelmann at qt.io
Wed Jun 21 12:28:38 CEST 2017

Hello Elvis,

Haswell and Ivy Bridge indeed ring a bell here. We have a lot of
WebEngine bug reports that affect these GPUs only.
Can you create a bug report please?

OpenGL 3.2 context raises an eyebrow here, because just yesterday I have
seen a qtdiag output from a Debian 7 machine (2013 isn't THAT long ago)
with mesa 8.0.5, which only supports OpenGL 3.0.

Kind regards

On 21.06.2017 11:38, Elvis Stansvik wrote:
> This may or may not be a Qt issue.
> I'm trying to help the VTK folks narrow down a problem with their new
> QVTKOpenGLWidget, which is a newly-introduced QOpenGLWidget-based
> class for letting VTK render into a QOpenGLWidget.
> The problem manifests itself as volume renderings not showing up on
> Windows machines with Ivy Bridge (e.g HD4000) and Haswell (e.g.
> HD4600) Intel GPUs when using the new class. VTKs volume rendering is
> done using float textures.
> Volume renderings works fine on the same machines when using "plain"
> VTK. This is when VTK itself sets up the OpenGL context (using GLEW I
> believe), but apart from that, the rendering pipeline is exactly the
> same I think. This is what leads me to believe that the issue is
> something specific to QOpenGLWidget, or to how VTK uses it.
> VTK requests a OpenGL 3.2 core context, and through some debugging,
> I've verified that VTK is actually getting the context that it is
> requesting.
> The issue is reported by me, here at VTKs GitLab:
>    https://gitlab.kitware.com/vtk/vtk/issues/17058
> The report contains some more information, such as the generated
> fragment shader that VTKs volume rendering backend is using, and a GL
> report from the problematic machine.
> Does this specific issue (float texture rendering not showing up on
> these semi-old Intel GPUs) ring a bell to anyone else?
> Many thanks for any tips/pointers/leads on how to debug this.
> I'm really interested in getting this issue in VTK fixed, since
> laptops with these GPUs are quite common. It's also affecting recent
> versions of ParaView, which has (just like me) recently ported to the
> new QVTKOpenGLWidget.
> Elvis
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest


Viktor Engelmann
Software Engineer

The Qt Company GmbH
Rudower Chaussee 13
D-12489 Berlin
Viktor.Engelmann at qt.io
+49 151 26784521

Geschäftsführer: Mika Pälsi,
Juha Varelius, Mika Harjuaho
Sitz der Gesellschaft: Berlin,
Registergericht: Amtsgericht
Charlottenburg, HRB 144331 B

The Future is Written with Qt

More information about the Interest mailing list