Unsolved Font corruption using OpenGL rendering
I just did an upgrade from Qt5.4.1 to Qt5.11.3 on my embedded system. One of the problems I saw is that for some reason, some of the texts have corrupted characters/glyphs. It looks like this:
I tried using various QT environment variables. The only environment variable that helped was QT_QUICK_BACKEND=software. That's not a real solution though, as rendering with CPU is really slow.
I am looking for ideas, because I feel I tried everything (besides digging into the OpenGL stack and GPU drivers). At this point, I just want to rule out problem in Qt.
Here is a minimal reproducible example - a Qt application that just generates a lot of different-sized labels that are updated each 10 seconds or so: https://github.com/pohlondrej/OpenGlTextCorruptionTest
I will be grateful for any suggestion.
I see there are no ideas, so I will list a bunch of things I tried (and that did not work) since I created this post - someone might find these useful, so just for completeness:
- Upgrading to Qt5.12.6
- Updating GPU drivers
- Adding Wayland + Weston stack and running the application under it
- Using and old version of bootloader (I thought perhaps the onboard memory configuration changed, and bootloader is configuring the memory)
- Tried both -system-freetype and -qt-freetype configurations
Any ideas are highly appreciated.
Another observation: the behavior looks almost exactly like https://bugreports.qt.io/browse/QTBUG-12370
Could this be some type of regression?