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Forums Adobe After Effects Expressions Smooth Change Color linked to a slider

  • Smooth Change Color linked to a slider

  • massimo ghidini

    May 3, 2020 at 1:23 pm

    Hi everyone!
    This is my little problem:

    I need to create some bars go up&down with different colors applied within this range:

    0-30% red
    30-70% yellow
    70-100% green

    All of that must be linked to a slider. So, there aren’t any problems if the color change on the limit, in a pop way I mean,
    because I wrote something like this on the stroke property:

    r= thisComp.layer(“100%”).effect(“Control Number”)(“Slider”);
    if (r<=30){[255,0,0,1]};
    if(r>30 && r<70){[255,234,0,1]};

    But I really need to create smooth transition from one color to the other one.
    I tried different ways…but nothing works!

    The last script I wrote is this one:

    Col=thisComp.layer(“100%”).effect(“Control Number”)(“Slider”);

    if(Col>30 && Col<70){yellow};


    And the color returns always yellow.
    I found some other topic similar to this one but it was around hex numbers, so I had some problems to convert that model into the one I need…

    Hope to get back some useful tips!!!
    Thank you so much!


  • Dan Ebberts

    May 3, 2020 at 4:29 pm

    It’s not clear how you want the colors to change exactly, but this example would change from red to green (with yellow in the middle) across the full range of the slider:

    Col=thisComp.layer("100%").effect("Control Number")("Slider");
    if (Col < 50)
    linear (Col,0,50,red,yellow)
    linear (Col,50,100,yellow,green)


  • massimo ghidini

    May 3, 2020 at 4:44 pm

    Hi Dan!
    Thanks so much…it works perfectly!!! ☺

    Can I ask you to explain why You use the arrays with values 1 or 1.5 instead of 2**, please?
    I’m a beginner with all this process.
    Thanks a lot anyway!


  • Dan Ebberts

    May 3, 2020 at 5:07 pm

    Oops, there’s a mistake in there. Yellow should be:


    In expressions, the color values are normalized to be between 0.0 and 1.0 and expressed as arrays:


    So red is [1,0,0,1], white is [1,1,1,1] etc.


  • Nithish kumar

    May 5, 2020 at 2:00 am

    Hi massimo ghidini

    Pls pay attention that ita a comma between 1 and 5. It’s not 1.5…coz color values can be only from 0 to 1….


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