Fade images using Shader Effect

[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

[timday]

@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.

[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.

[timday]

@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.