• Adobe After Effects Expressions

  keyframe overshoot based on another layer’s movement

  Posted by Matt Howarth on October 7, 2015 at 9:46 am

  Hi all

  I’m trying to give a puppet tool pin inertial bounce when the tubby pig character moves. I was using the fantastic expression from Dan Ebbert’s moitionscript.com (again!!!, it’s a brilliant site – nice one Dan) and thought if I changed the line:

  n = nearestKey(time).index;

  to

  n =transform.position.nearestKey(time).index;

  it would work, but it tells me:
  this property has no keyframe number 2

  even though it does have two keyframes.

  I then tried driving it with a null:
  n=thisComp.layer(“Null4”).transform.position.nearestKey(time).index;

  and got the same error.

  What am I doing wrong?

  thanks

  Matt

  freq = 3;
decay = 5;

  n = 0;
if (numKeys > 0){
n =transform.position.nearestKey(time).index;
if (key(n).time > time) n--;
}
if (n > 0){
t = time - key(n).time;
amp = velocityAtTime(key(n).time - .001);
w = freq*Math.PI*2;
value + amp*(Math.sin(t*w)/Math.exp(decay*t)/w);
}else
value

  Visual tinkerer and easily distracted admirer of all things shiny! – writer – animator – digital artist

  Matt Howarth replied 10 years, 7 months ago 2 Members · 3 Replies
• 3 Replies

• 

  Dan Ebberts

  October 7, 2015 at 8:05 pm

  I think it would be more like this:

  
freq = 3;
decay = 5;

  p = transform.position;

  n = 0;
if (p.numKeys > 0){
n =p.nearestKey(time).index;
if (p.key(n).time > time) n--;
}
if (n > 0){
t = time - p.key(n).time;
amp = p.velocityAtTime(p.key(n).time - .001);
w = freq*Math.PI*2;
value + amp*(Math.sin(t*w)/Math.exp(decay*t)/w);
}else
value


  Dan
• 

  Matt Howarth

  October 8, 2015 at 8:06 am

  Dan,

  many thanks once again for taking the time to respond. You have a knack for replying with the correct response without making the person asking the question feel stupid in any way. It’s very much appreciated. : )

  I will give it a try this morning

  cheers

  Matt

  Visual tinkerer and easily distracted admirer of all things shiny! – writer – animator – digital artist
• 

  Matt Howarth

  October 8, 2015 at 11:01 am

  Hi Dan

  that worked an absolute treat!

  Many thanks

  Matt: )

  Visual tinkerer and easily distracted admirer of all things shiny! – writer – animator – digital artist

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