• Adobe After Effects

  Expression Help with moving a null layer to the left 120 pixels every 3 seconds

  Posted by Matt Sonberg on October 18, 2006 at 6:22 pm

  Every 3 seconds I’d like to move my null layer to the left by 120 pixels. I have to do this many times over. How can I write an expression to do this? I figure it’s pretty simple, but I have very little experience with expressions.

  Thanks as always!

  Mike Clasby replied 19 years, 7 months ago 4 Members · 5 Replies
• 5 Replies

• 

  Julian Sixx

  October 18, 2006 at 6:45 pm

  Hi
  yikesmikes it’s my turn this time 😉

  hold_time=3;
  l=Math.floor(time/hold_time)
  value+[l*-120]
• 

  Mike Clasby

  October 18, 2006 at 6:57 pm

  Drats! Foiled again.
• 

  Matt Sonberg

  October 18, 2006 at 8:50 pm

  This is perfect… almost. I guess I should have asked this in the first place. How can I ease in and out of each of these movements? I want the null to slide to the left, starting and stop in a smooth motion.

  yikesmikes… I’m giving you another shot!
• 

  Dan Ebberts

  October 18, 2006 at 9:11 pm

  Something like this maybe:

  period = 3;
  deltaX = -120;
  easeTime = .5;

  t = time % period;
  prevX = Math.floor(time/3)*deltaX;
  nextX = prevX + deltaX;
  currX = ease(t,0,easeTime,prevX, nextX);
  value + [currX,0];

  Decrease “easeTime” to reduce travel time between positions.

  Dan
• 

  Mike Clasby

  October 18, 2006 at 9:52 pm

  Or you could keyframe one cycle of the movment the way you like, ease keyframe for 3rd keyframe (and tweak its bezier if you want), then add this loop expression.

  loop_out(“offset”,0)

Reply to this Discussion! Login or Sign Up