Hi Patrick, The bug is not known to me, but it looks like there is a bug with the geometry being passed to OpenGL by the rendering code. A hint that may help you track down the root of the problem could be too specify the environment variable QSG_RENDERER_DEBUG=upload and look at the vertexdata. There'll be a lot of output there, but it might help to provide some pointer as to where the problem lies.
If you manage to make a testcase that consistently reproduces it, please file the bug to bugreports.qt.io. cheers, Gunnar > On 19 Oct 2016, at 23:22, patrick.fl...@continental-corporation.com wrote: > > Hi, > I got the recommodation to send my question/problem to this mailing list. > > On our i.MX6 based target device we can observe sporadic rendering problems > when using QtQuick. > As the problem is only happening sporadic we were not able to create a > specific code that is causing the rendering problem. > > Background information: our system has two framebuffers, Qt is rendering in > the foreground framebuffer. > We are using Qt 5.6 running on a Linux Kernel 3.10.17 (patches from NXP for > the iMX6 are applied), including latest opengl libraries from NXP. > > We have seen two issues: > 1. Triangle showing parts of the background framebuffer. > > 2. Warped Graphics > > We have already started a discussion with NXP regarding that issue. > The last statement from NXP is: > 1. Eventually I suspect here an error in the QT framework when passing > the mesh to OpenGL. It can be that for example a very simple geometry is used > in the vertex buffer (e.g. 2 triangles defining the full frame buffer) but in > the end 3 or more triangles are specified due to an application software > error, so the OpenGL pipeline tries to render a 3rd triangle. For that it > reads the coordinates from the vertex buffer (that contains valid data only > for 2 triangles !), and thus invalid data is read therefore random triangles > appear on the screen. > 2. In this example again it looks like a geometry problem. Because the > texture containing the gauge appears to be mapped on a strange 2d mesh > composed by two incomplete circles. My idea with alpha was just to confirm > that some draw primitives are corrupted, which is pretty clear now. > > Does anybody know about existing Qt bugs which could cause the issue we can > observe? > Any ideas how to debug this issue? > > Thanks a lot. > > Patrick > > http://www.continental-corporation.com > > <Mail Attachment.jpeg> > ________________________________________________________________________ > > Continental Automotive GmbH, Vahrenwalder Str. 9, D-30165 Hannover > Vorsitzender des Aufsichtsrats/Chairman of the Supervisory Board: Helmut > Matschi > Geschaeftsfuehrer/Managing Director: Georg Sistermanns, Harald Stuhlmann > Sitz der Gesellschaft/Registered Office: Hannover > Registergericht/Registered Court: Amtsgericht Hannover, HRB 59424, > USt.-ID-Nr./VAT-ID-No. DE814950663 > ________________________________________________________________________ > > Proprietary and confidential. Distribution only by express authority of > Continental AG or its subsidiaries. > > <issue_1.jpg><issue_2.jpg>_______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
