• Adobe After Effects

  is it possible to us expression for exponential scale?

  Posted by Ryan Chan on April 27, 2005 at 3:21 pm

  hello Dan and everybody, i just wondered if it is possible to use expression to achieve the same result as using exponential scale, so, i can modify the from/to value more easily? say, from 25% scale up to 2500% in 5sec, how to write the expression for this interpolation? thanks

  ryan

  Mike Clasby replied 21 years, 4 months ago 4 Members · 4 Replies
• 4 Replies

• 

  Dan Ebberts

  April 27, 2005 at 3:46 pm

  Try this:

  
  v1 = 25;
  v2 = 2500;
  t1 = 0; //start time
  t2 = 5; //end time
  
  if (time <= t1){
    s = v1;
  }else if (time > t1 && time < t2){
    t = time - t1;
    T = t2 - t1;
    k = Math.log(v2/v1)/T;
    s = v1*Math.exp(k*t)
  }else{
    s = v2;
  }
  [s,s]
  
  
  

  Dan
• 

  Andrew Kramer

  April 27, 2005 at 3:58 pm

  Dan this is very creative how you solved this. Do you think you can explain it a little bit. Also could this be done with a linked slider.

  so if you keyframed the expression slider value at say 10 and then to 100 equal to scale would be 100-10000.

  this way you could alter it visually with keyframes.

  thanks
  Andrew
• 

  Ryan Chan

  April 28, 2005 at 1:53 am

  thanks Dan, you,re incredible! although it is far more complicated than i expected, but i will try to “Digest” this expression, thanks again.
  ryan
• 

  Mike Clasby

  April 28, 2005 at 8:01 pm

  Very cool little expression. It looks great on a 3D solid in Custom view 1, so you can actually see what’s going n. Thanks.

Reply to this Discussion! Login or Sign Up