• Adobe After Effects Expressions

  Rotate with an inertial bounce? Also scale?

  Posted by Jim Dodson on October 12, 2012 at 4:10 am

  My new favorite expression (new to me at least) gives a nice inertial bounce on position values.

  Here it is (with Dan’s fix for divide by zero error):

  amp = .03;
  freq = 3.0;
  decay = 9.0;
  n = 0;
  if (numKeys > 0){
  n = nearestKey(time).index;
  if (key(n).time > time){
  n–;
  }}
  if (n == 0){ t = 0;
  }else{
  t = time – key(n).time;
  }
  if (n > 0 && t < 1){
  v = velocityAtTime(key(n).time – thisComp.frameDuration/10);
  value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
  }else{value}

  My question is: Is there a similar inertial bounce expression for Rotation? ALSO
  For scale?

  Thanks guys!!

  Jim Dodson

  8 Core Intel — Mac – OSX

  Jim Dodson replied 13 years, 7 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  October 12, 2012 at 5:07 am

  Did you try it with scale and rotation? It should be property agnostic.

  Dan
• 

  Jim Dodson

  October 12, 2012 at 2:36 pm

  ** Success**

  Turns out it works for scale (the amplitude was subtle so had to be increased to be noticeable). But, I got this error on orientation:

  “Velocity is not supported for the orientation property.”
  So it had to be used on “Rotation” where it worked PERFECTLY. (I really did test this before I posted Dan, I just didn’t see the bounce in the smaller icons because they were subtle — increasing amplitude helped.)

  As always Dan, thank you for your amazing talents!!

  Jim Dodson

  8 Core Intel — Mac – OSX

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