• Adobe After Effects Expressions

  Linking positions

  Posted by Marten Kopp on January 9, 2009 at 11:34 pm

  Hi,

  I am kind of new to after effects expressions. I am building a comp with a bunch of clips. The result should be like a video wall. But I would like to make it easy update-able. So I started figuring out the use of expressions and came up with this:

  x = thisComp.layer(thisLayer, -1).transform.position[0] + 800;
  y = thisComp.layer(thisLayer, -1).transform.position[1] + 0;
  z = thisComp.layer(thisLayer, -1).transform.position[2] + 0;

  if ( x >2000) {
  x = thisComp.layer(thisLayer, -1).transform.position[0] – 1600;
  y = thisComp.layer(thisLayer, -3).transform.position[1] + 650;
  }else{
  x = thisComp.layer(thisLayer, -1).transform.position[0] + 800;
  y = thisComp.layer(thisLayer, -1).transform.position[1] + 0;
  z = thisComp.layer(thisLayer, -1).transform.position[2] + 0;
  }

  [x,y,z]

  I have the feeling I am in the right direction, cause is lines up the clips in rows of 3. After every thirth video it put’s the 4th on the next row. But disaster strikes when I start to move my first layer.

  Is there a way to replace the:

  if ( x >2000) {

  with something that would be like:

  If the x is bigger then the x of thisLayer -3 + 2400 then…

  Cause it seems the expresion is mixing up the x of the workarea with the x of the first layer.

  Since I am asking this question, I could also ask another. Just a simple one. I found out you can easily lock positions with other layers. Or just link to there transformation options.

  Is it possible to link the expression of one layer to another? A more easy way then copying the same expression into all the layers?

  Any help is welcome..

  Dan Ebberts replied 17 years, 3 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Dan Ebberts

  January 10, 2009 at 12:46 am

  Something like this is probably closer to what you’re looking for:

  columns = 3;

  row = Math.floor((index-1)/columns);
  col = (index-1)%columns;
  x = width/2 + col*width;
  y = height/2 + row*height;
  [x,y,value[2]]

  Dan

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