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    Unsolved Font corruption using OpenGL rendering

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    • P
      pohlondrej last edited by pohlondrej

      Hi,

      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:

      corrupt_text

      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.

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      • P
        pohlondrej last edited by

        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.

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        • P
          pohlondrej last edited by

          Another observation: the behavior looks almost exactly like https://bugreports.qt.io/browse/QTBUG-12370

          Could this be some type of regression?

          kshegunov 1 Reply Last reply Reply Quote 0
          • kshegunov
            kshegunov Moderators @pohlondrej last edited by

            @pohlondrej said in Font corruption using OpenGL rendering:

            Could this be some type of regression?

            Yes of course, or some change introduced a (new) bug or something else. Otherwise your code looks fine to me.
            My advice: post this on bugracker with the MRE alongside.

            Read and abide by the Qt Code of Conduct

            1 Reply Last reply Reply Quote 0
            • P
              pohlondrej last edited by

              @kshegunov thank you for reply!

              Just FYI, the link to the bug: https://bugreports.qt.io/browse/QTBUG-82703

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