• Adobe After Effects Expressions

  camera wobble

  Posted by Jglenn on June 5, 2007 at 5:06 pm

  i’m having trouble understanding harry frank’s (greymachine.com) camera wobble tutorial.
  heres the expression:

  t=time – key(2).time;
  if (t<0){
  value;
  }else{
  veloc = 18;
  amplitude = 60;
  decay =2;

  x=amplitude*Math.sin(veloc*time)/Math.exp(decay*time)
  value+ [x,x]}

  i understand the wobble part but don't understand what triggers the wobble. From the tutorial i think it has something to do with the second keyframe minus current time? i don't know. any way any help would be great.

  also could i use this expression for multiple camera movements in the same comp? each time the camera stops it wobbles?

  Thanks

  Kevin Camp replied 18 years, 11 months ago 3 Members · 2 Replies
• 2 Replies

• 

  Victor Nash

  June 5, 2007 at 6:05 pm

  Here is an expression for bouncing every other keyframe..

  n = 0;
  if (numKeys > 0){
  n = nearestKey(time).index;
  if (key(n).time > time){
  n–;
  }
  }
  if (n == 0 || n%2 != 0){
  value
  }else{
  t = time – key(n).time;
  veloc = 30;
  amplitude = 50;
  decay = 2;
  y = amplitude*Math.cos(veloc*t)/Math.exp(decay*t);
  value+[0,0,y];
  }

  “kis” it
  Keep it Simple
• 

  Kevin Camp

  June 5, 2007 at 8:56 pm

  t=time – key(2).time
  if (t<0){
  value

  i'm pretty new to expression, but not bad at math... what i believe this part of the expression says is that until the second keyframe (where current time would exceed the point in time of the second keyframe) just use the current value (i assume for position).

  but after that point (else) use the following expression to determine position:

  veloc = 18;
  amplitude = 60;
  decay =2;
  x=amplitude*Math.sin(veloc*time)/Math.exp(decay*time)
  value+ [x,x]}

  Kevin Camp
  Designer – KCPQ, KMYQ & KRCW

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