• Adobe After Effects Expressions

  Combining expressions

  Posted by Kim Bee on May 27, 2016 at 6:02 pm

  I have 3 “signs” on top of each other. They all swing down together and swing together but almost independently.

  I am currently using this expression:

  veloc = 7;
amplitude = 80;
decay = .7;
startT = thisLayer.startTime;

  amplitude*Math.cos(veloc*(time-startT))/Math.exp(decay*time)

  to make a sign fall down form X space and swing, then stop… However, I want it to continue to sway slowly afterwards without stopping.

  I found this expression (courtesy of https://www.motionscript.com/expressions-lab-ae65/swinging-light.html)

  amplitude = 7;
period = 3; //seconds

  amplitude*Math.sin(time*Math.PI*2/period)….

  And it does exactly what I need it to do except the falling down part. I added this to the end of the first code and it swayed after it swung down but it froze the top layer.

  How do I combine both so it falls down, decay, and then slowly sway for the amount of time I choose (i.e. the duration of the composition)?

  Thanks!

  veloc = 7;
amplitude = 80;
decay = .7;
startT = thisLayer.startTime;

  amplitude*Math.cos(veloc*(time-startT))/Math.exp(decay*time)

  amplitude = 7;
  period = 3; //seconds

  amplitude*Math.sin(time*Math.PI*2/period)

  Kim Bee replied 10 years, 3 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  May 27, 2016 at 6:42 pm

  The easiest might be to just blend the two expressions over a fixed period (I chose from 4 to 5 seconds for this example):

  veloc = 7;
  amplitude = 80;
  decay = .7;
  startT = thisLayer.startTime;
  v1 = amplitude*Math.cos(veloc*(time-startT))/Math.exp(decay*time);

  amplitude = 7;
  period = 3; //seconds
  v2 = amplitude*Math.sin(time*Math.PI*2/period);

  startEase = 4;
  endEase = 5;
  ease(time,startEase,endEase,v1,v2)

  Dan
• 

  Kim Bee

  May 27, 2016 at 6:49 pm

  Thank you!!

  That worked perfectly!!

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