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  • Adobe After Effects

    Expression Opacity

    Posted by Andy Burmeister on September 27, 2006 at 11:07 pm

    I have a bunch of layers and I want them to randomly change opacity within a given time range(frame 100-150)

    Let’s say layer 1 turns off within 15 frames starting on frame 100, then
    layer 2 turns off within 15 frames, lets say on frame 112….etc.

    I need to randomize the time (but have a fixed range) the layer starts fading out, yet I want it to only take 15 frames or so.

    hope I made myself clear

    thanks 🙂

    Andy Burmeister replied 19 years, 7 months ago 2 Members · 2 Replies
  • 2 Replies

  • Dan Ebberts

    September 28, 2006 at 4:50 am

    Something like this should do it:

    fadeMin = 100;
    fadeMax = 150;
    fadeDuration = 15;

    seedRandom(index,true);
    fadeStart = random(fadeMin,fadeMax-fadeDuration);
    d = thisComp.frameDuration;

    linear(time,fadeStart*d,(fadeStart+fadeDuration)*d,100,0)

    Dan

  • Andy Burmeister

    September 28, 2006 at 5:16 am

    works like a charm, you’re a genius Dan,

    thanks 🙂

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