Qt6 topics merged with General

OpenGL RPi2 Arch Qt5 blank screen hangs no display

  • update when launching a QML app from platform mode
    example:# ./app -platform linuxfb
    what other options should I use ? for example dose "Graphical Effects" need to know anything? like driver?

    So in qtcreator there is several examples
    The "gallery" (QT Quick Extras - Gallery) one uses sliders menu and is great demo! ( it uses OpenGL it looks like )

    On the Rpi2 with Archlinux, the "gallery" app will run in Xfce4 but its painfully slow, like sad slow as if Open GL is getting emulated like 10+ years ago when you'd play q3atest.

    and trying to run without X11 xorg, from console " ./app -platform linuxfb " it looks to launch but nothing pops up on the screen and the system seems to hang. (it doesn't hang because i can ssh reboot and things comeback)

    i'm thinking there is a conflict with the mesa-lib (that gets installed with qt5-base) AND the secret sauce broadcom GPU stuff. I can't remove mesa without removing qt5 :-/
    I was told this is all supposed to be ironed out Qt + RPi , also why i think its a library Arch Linux install issue maybe?

    note a generic hello world design thing qt app runs both ways. (but i'm guessing isn't open gl

    Thanks :-)

  • same thing happens with Debian Jessie on the pi .
    now to try raspbian (which my work won't let me use, but i can at-least test against it)

  • Hi sirmonkey,

    Where did you get the debian jessie image?

    I ask because when using a raspbian image all hw use is optimized and opengl 2 is used if i recall correctly. I doubt your images has been tuned for the pi hw.


  • @Eddy http://sjoerd.luon.net/posts/2015/02/debian-jessie-on-rpi2/ is where i started.
    do you know of an image that works?

    Tonight I'm going to try to do a
    apt-get dist-upgrade
    on Raspbian and see what happends

  • Update:
    after some reading. it looks like the ArchLinuxARM package of Qt5 is compiled with OpenGL3
    the RaspberryPi2 is OpenGL2. so in X it gets emulated in Mesa.

    but there is probably other issues aswell maybe? I don't know

    Is it possible to tell Qt on the command line which to use, or do I have to recompile Qt5 on the pi?

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