• Adobe After Effects Expressions

  Position change triggers opacity ramp-down event.

  Posted by Waldemar Werbel on May 12, 2013 at 4:42 pm

  Hi all,

  I’d like to use an expression in a layer’s opacity parameter which looks for a change in the same layer’s position. When there is a change in position, I’d like the expression to ramp the layer’s opacity value down from 100 to 0 over 4 frames.

  The layer’s default opacity would be 0 – basically, the layer flashes on briefly every time its position changes. Here’s a .gif to illustrate how it would look in keyframes…

  

  Thanks in advance for any help you can offer!

  Waldemar Werbel replied 13 years, 3 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  May 12, 2013 at 5:27 pm

  I think this will work:

  
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;
ease(t,0,framesToTime(4),100,0);
}else{
0
}


  Dan
• 

  Waldemar Werbel

  May 12, 2013 at 5:33 pm

  Thanks Dan.

  That worked a treat.

  Very much obliged to you!

  Wal.

Reply to this Discussion! Login or Sign Up