• Adobe After Effects Expressions

  Wiggle + Inertial Bounce

  Posted by Andres Torres on January 4, 2010 at 4:17 pm

  I’m trying to wiggle only the Y position property of a 3D layer AND have the “inertial bounce” expression applied.

  I’d also like to pickwhip the position of a second layer to the position of the 1st (the wiggle+inertial bounce layer) and apply the position before the inertial bounce (i.e. the original position of layer 1 before inertial bounce affects the values)

  Many thanks to the geniuses!!

  // Inertial Bounce (moves settle into place after bouncing around a little)
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){
v = velocityAtTime(key(n).time - thisComp.frameDuration/10);
amp = .05;
freq = 4.0;
decay = 2.0;
value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
}else{
value;
}

  Benjamin Ducroz replied 16 years, 3 months ago 3 Members · 4 Replies
• 4 Replies

• 

  Dan Ebberts

  January 4, 2010 at 6:37 pm

  Interesting problem. You left out some important details, so this is just a guess as to what you’re after. This expression adds a y wiggle in addition to the inertial bounce. It also “publishes” the value without the inertial bounce at negative times:

  wAmp = 100;
  wFreq = 1;
  if (time < 0){ w = wiggle(wFreq,wAmp,1,0.5,-time); [valueAtTime(-time)[0],w[1]]; }else{ w = wiggle(wFreq,wAmp); 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){
  v = velocityAtTime(key(n).time – thisComp.frameDuration/10);
  amp = .05;
  freq = 4.0;
  decay = 2.0;
  [value[0],w[1]] + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
  }else{
  [value[0],w[1]];
  }
  }

  If you want another layer to follow the non-inertial-bounce motion of the original layer, you’d use an expression like this:

  thisComp.layer(“Black Solid 1”).transform.position.valueAtTime(-time)

  I hope that’s close to what you were after.

  Dan
• 

  Benjamin Ducroz

  April 17, 2010 at 7:37 am

  this is a really handy script for the job i’m working on.
  i can’t find the co-ordinates in this.
  how can i make it wIggle on both X & Y?
• 

  Dan Ebberts

  April 17, 2010 at 2:11 pm

  Try changing the last part of the expression to this:

  [w[0],w[1],value[2]] + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
  }else{
  [w[0],w[1],value[2]];
  }
  }

  Dan
• 

  Benjamin Ducroz

  April 18, 2010 at 12:22 am

  Thank you Dan, much appreciated!
  it did not work at first, but I got the error

  Class ‘Array’ has no property or method named ‘2’.

  I tried replacing the 2 with 1 and this worked.
  So the full working script is as follows:

  i’ve used this expression on puppet pins. and it works really well for what i’m doing.

  really appreciate the help, thanks again!

  wAmp = 100;
wFreq = 1;
if (time < 0){
w = wiggle(thisComp.layer("WIGGLE").effect("wiggle_amount")("Slider"),thisComp.layer("WIGGLE").effect("wiggle_rate")("Slider"),1,1,-time);
[valueAtTime(-time)[0],w[1]];
}else{
w = wiggle(thisComp.layer("WIGGLE").effect("wiggle_amount")("Slider"),thisComp.layer("WIGGLE").effect("wiggle_rate")("Slider"));
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){
  v = velocityAtTime(key(n).time - thisComp.frameDuration/10);
  amp = .05;
  freq = 4.0;
  decay = 2.0;
  [w[0],w[1],value[1]] + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
  }else{
  [w[0],w[1],value[1]];
  }
  }

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