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
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