• Adobe After Effects Expressions

  Random fade in/out of multiple layers so only one layer is visible at a time

  Posted by Al Mach on October 13, 2021 at 8:45 pm

  I have 27 layers that I want to randomly appear (quick fade on then fade off), but not overlap so that if one is at full opacity the others are invisible. Is this possible?

  Al Mach replied 4 years, 10 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  October 13, 2021 at 9:20 pm

  Just as a quick demo, create a null named “Control” with a Slider Control and keep this layer at the bottom of your layer stack (below your 27 layers). Add this expression to the slider:

  n = 27;
  period = 1;
  seg = Math.floor(time/period);
  seedRandom(seg,true);
  Math.floor(random(n)) + 1;

  This will broadcast an integer between 1 and 27 for the other layers to use to decide whether to fade up or not. Apply this opacity expression to your 27 layers:

  period = 1;
  fadeTime = .25;
  t = time%period;
  targetLayer  = thisComp.layer("Control").effect("Slider Control")("Slider");
  if (targetLayer == index){
    if (t < fadeTime)
      ease(t,0,fadeTime,0,100)
    else
      ease(t,fadeTime,fadeTime*2,100,0);
  }else
    0

  Adjust the period and fadeTime (fadeTime should be half the period, or less).
• 

  Al Mach

  October 13, 2021 at 9:43 pm

  Thank you, it worked perfectly.

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