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Font corruption using OpenGL rendering

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    pohlondrej
    wrote on last edited by pohlondrej
    #1

    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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      pohlondrej
      wrote on last edited by
      #2

      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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        pohlondrej
        wrote on last edited by
        #3

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

        Could this be some type of regression?

        kshegunovK 1 Reply Last reply
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        • P pohlondrej

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

          Could this be some type of regression?

          kshegunovK Offline
          kshegunovK Offline
          kshegunov
          Moderators
          wrote on last edited by
          #4

          @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

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            pohlondrej
            wrote on last edited by
            #5

            @kshegunov thank you for reply!

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

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