• Adobe After Effects Expressions

  Pulling min and max data from keyframes

  Posted by Brock Jolet on February 19, 2013 at 9:49 pm

  I’m trying to write an expression that would dynamically adjust according to the minimum and maximum values that are keyed.

  For example, if I keyed the opacity of a layer from 0 to 50 then back to 25, the minimum value would be 0 and the maximum value would be 50.
  If I then changed one of the keyframes to -25, that would dynamically become the new minimum value.

  My goal is to then use these two values (minimum and maximum) in a subsequent linear function that controls a separate process. I’m not sure where to start with this one and any help would be appreciated. I’m hoping it’s a very simple function that I cannot find.

  Brock Jolet replied 13 years, 2 months ago 2 Members · 3 Replies
• 3 Replies

• 

  Dan Ebberts

  February 19, 2013 at 10:34 pm

  Something like this should work:

  
myProp = transform.opacity;
if (myProp.numKeys > 0){
myMin = 9999;
myMax = -9999;
for (i = 1; i <= myProp.numKeys; i++){
myMin = Math.min(myMin,myProp.key(i).value);
myMax = Math.max(myMax,myProp.key(i).value);
}
}else{
myMin = myMax = myProp.value;
}


  Dan
• 

  Brock Jolet

  February 19, 2013 at 10:38 pm

  Thank you very much. This successfully pulls the maximum value and since it’s opacity, the minimum will be zero. Just for curiosity’s sake, how would I extract the minimum from this expression should it differ?
• 

  Brock Jolet

  February 19, 2013 at 10:41 pm

  Nevermind, I figured it out. Brain fart. Thanks again.

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