Hello, I’m new to PsychoPy and am currently trying change the opacity of an image depending on the current slider position. What have I tried so far? lightbulb_slider.psyexp (10.5 KB) I created a slider, and put two versions of two images (a lightbulb) at the same coordinates. Lightbulb off on t…

[image] kizilirmak: insight.opacity = opac/100 ‘’‘in theory, this is unnecessary, because this is under every_frame tab and within the GUI for the lightbulb off image the opacity is set to every_frame’’ Either set the opacity as opac/100 every frame or set it in code, not both.

Instead of using slider.getRating(), try using slider.markerPos. The getRating call only provides the marker position after the choice has been made, whereas markerPos will give the current position of the marker

Thank you for the suggestion! I also tried this under Each Frame: opac = aha_slider.markerPos() or 0 # rating from 0 to 100 insight.opacity = opac But it did not work. I thought it may be important to set a marker position at the beginning of the routine, because by then the participant will not h…

What kind of value does markerPos normally contain? An integer? A list of two values [0,0]? It is a pity I cannot find it in the PsychoPy documentation.

I use markerPos in my interactive slider demo. You could take a look there. [image] PsychoPy Online Demos Blog If you have routines or experiments that are likely to be useful to others, please create a post in this thread, editing your post to add new demos so there is on…

It should work, although in your code you called it as a function, but it is a property. So, try without the function call. opac = aha_slider.markerPos or 0

You’re right! The code runs now, but the lightbulb only changes from one state into the other without gradual change in transparency… I hope I find this probably more logical error. Do I need to use the “mask” feature of an image for transparency? Or could my way of laying two identical images with…

Having layered images and changing the opacity should work. Just to confirm, might be worth printing the opacity just to make sure the range of values is between 0 and 1 as a float, and not a 0 or 1 as an integer. # Each Frame print(opac, aha_slider.markerPos)

It works! Thank you for pointing this out! Of course, when I reset the value of opac every frame via those attributes entered via GUI and then also by changing them every frame via code, they overwrite each other all the time. I never thought about it. This code/GUI hybrid is a bit confusing. Here …

Cool. If it works online, perhaps you’d like to add it as a demo to this thread. [image] PsychoPy Online Demos Blog If you have routines or experiments that are likely to be useful to others, please create a post in this thread, editing your post to add new demos so there…

Yes! During all the editing of those few lines, at some point I must have tried without the /100 and forgot it ever since. Have re-added it: opac = 100 - aha_slider.markerPos or 0 # rating from 0 to 100 insight.opacity = opac/100

Change opacity of image continuously with slider position

Builder

wakecarter May 21, 2021, 10:07am 5

I use markerPos in my interactive slider demo. You could take a look there.

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Change opacity of image continuously with slider position

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