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Qt OpenGL poor window resizing experience.



  • Hello,

    I've recently started playing around with Qt and was working on animations. They didn't run smoothly, so I decided to switch over to OpenGL as the renderer. All was good until I tried to resize the window.

    Googling did not help at all (probably because I don't know what terms to put in the search bar to find more fitting results).

    Thought maybe this had something to do with me running a 32bit compiler. Tried x64 MSVC2019 and MinGW, still the same.

    Opened up the "Qt Hello GL 2 Example", it's the exact same effect:
    https://youtu.be/XOrXbjkHu0M
    (Though YouTube isn't the best to show the stuttering, it's close enough)
    The window itself runs at 60 FPS, but drops to about 10 when resizing.

    Am I doing something wrong, is this just an OpenGL issue? I'm really confused.

    Thank you for taking your time to read this.

    EDIT: I've checked the GPU usage.
    Spinning the Qt model around used about 10%
    Resizing the window used about 15%

    I also use Qt 5.15.2


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