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Fade images using Shader Effect

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  • L Offline
    L Offline
    luca
    wrote on last edited by luca
    #1

    Hi all,
    I'm interested in Shader Effect because I thinks to understand it's less hungry of resources.
    Is there a very simple example to fade an image using QML/ShaderEffect ?

    Thanks

    timdayT 1 Reply Last reply
    0
    • L luca

      Hi all,
      I'm interested in Shader Effect because I thinks to understand it's less hungry of resources.
      Is there a very simple example to fade an image using QML/ShaderEffect ?

      Thanks

      timdayT Offline
      timdayT Offline
      timday
      wrote on last edited by
      #2

      @luca You can fade an image in and out more simply by simply animating its opacity smoothly between 0.0 and 1.0. Cross fade between images by stacking one on top of the other and fading the top one out.

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      • L Offline
        L Offline
        luca
        wrote on last edited by
        #3

        Thanks, I already faded images as you describe but I'm running my application on a BeagleBone (embedded linux) and it's not so smooth.
        I'd like to try some alternatives to get better result.

        timdayT 1 Reply Last reply
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        • L luca

          Thanks, I already faded images as you describe but I'm running my application on a BeagleBone (embedded linux) and it's not so smooth.
          I'd like to try some alternatives to get better result.

          timdayT Offline
          timdayT Offline
          timday
          wrote on last edited by
          #4

          @luca Seems surprising. I'd have assumed QML element opacity was implemented very efficiently using OpenGL. If that's not smooth it suggests the BeagleBone has very very underpowered OpenGL HW, or is falling back on a SW OpenGL emulation. Either way ShaderEffect isn't likely to help.

          Quick google of "BeagleBone OpenGL" suggests it's non-trivial to get OpenGL HW acceleration to work. Are you absolutely sure graphics HW is being used? Personal experience is that Linux systems can fall back to Mesa SW emulation very easily and transparently, and often poor performance (accompanied by high CPU load) is the only clue that SW fallback is being used.

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