Qt Forum

    • Login
    • Search
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Groups
    • Search
    • Unsolved

    Unsolved Qt + OpenGL: pictures in OpenGL widgets swap.

    General and Desktop
    2
    6
    1671
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • Teh Me
      Teh Me last edited by

      Hello. I have an application that renders multiple OpenGL 'screens'. in multiple windows. Image data for screens is in YUV colorspace. Shaders translate it to RGB. For each screen I use 3 textures: for Y, U and V respectively, and combine them in shader.
      When have 2 windows and add 1 screen to each one, pictures in screens start swapping randomly. It does not happen when I use 1 texture (for example, just drawing RGB images).
      Unfortunately, I can't reproduce this issue in a sketch application. Please give me some hint where I can find info about this issue. Can Qt be involved in this issue, or is it OpenGL or me?

      1 Reply Last reply Reply Quote 0
      • SGaist
        SGaist Lifetime Qt Champion last edited by

        Hi and welcome to devnet,

        If you can't reproduce that in a "dummy" application, then it's likely that you are doing something wrong. However without seeing any code it's pretty difficult to tell you what might be going wrong. Did you check that your context are always current ? Are you sharing one context across several widgets ?

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

        1 Reply Last reply Reply Quote 1
        • Teh Me
          Teh Me last edited by

          Hello, SGaist. Sorry for my late answer.
          Contexts of corresponding widgets are always current at the time of drawing (in paintGL()). And they are always different for different widgets. I did not share them explicitly, can there be any implicit sharing?
          I will try to reproduce the issue again. If I succeed, I will post the code.
          If you have more ideas what can I check, post them, please. Thank you.

          1 Reply Last reply Reply Quote 0
          • Teh Me
            Teh Me last edited by

            @SGaist, take a look please.
            I reproduced the issue successfully.
            This is the example application.
            To reproduce the issue start the application, open .yuv files in each window, then move mouse from and to button several times in any window. OpenGL widget will show a frame from other file.

            1 Reply Last reply Reply Quote 0
            • SGaist
              SGaist Lifetime Qt Champion last edited by

              Sorry, my current system doesn't provide that OpenGL profile currently.

              In any case, what kind of YUV image is it ? 4:4:4 ? 4:2:2 ?

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

              1 Reply Last reply Reply Quote 0
              • Teh Me
                Teh Me last edited by

                @SGaist, files in project are in YV12 format.
                Here is the video of what is happening.
                First, I open yuvnumbers1 file (white background) in first window. Next, I open yuvnumbers2 file (green background) in second window. Pictures swap immediately. Then I move mouse cursor from and to open button (cursor is not seen, but button becomes highlighted), and pictures swap again for a moment. Same for other window.
                Sometimes video in window that opened file second just freezes. UpdateRequest events are received, but Paint events occur only when I move the cursor over button, or move the window.

                1 Reply Last reply Reply Quote 0
                • First post
                  Last post