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Grating stim opacity on Raspberry Pi

I don’t think that opacity is being recognised on my Pi:

    grate = visual.GratingStim(win=mywin,  size=20,  sf=0.8, contrast=0.3)
    mask  = visual.GratingStim(win=mywin,  size=20,  sf=0.4, contrast=0.3, ori = 90, opacity=0.5)
.....
       grate.draw()  
        mask.draw()

Only shows the mask on a Pi, but shows the plaid fine on a Intel Linux and Mac. Is this a known bug ? How to generate the plaid on the Pi ?

thanks
chris

Sort of - but not a known bug with PsychoPy. All of our visual stimuli rely on OpenGL to draw, and OpenGL is only partially supported on Pi, so while some PsychoPy functions will work on Pi, we don’t officially support it.

Does opacity work for other stimuli? If not then I’d guess that the alpha channel on OpenGL colours isn’t recognised by Pi

The RPi is not currently supported. We need to rework the graphics pipeline to make it happen. It’s something that is planned though.

Thanks both for your reply. For now, I have made the stimuli in Numpy arrays, and these work fine

chris