• Adobe After Effects Expressions

  ExtendScript – add expression to opacity property

  Posted by Paul Connors on November 1, 2016 at 3:49 pm

  Hello,

  I’m currently writing a script and am stuck on trying to automatically add an expression to a specific composition. Currently my script creates a new comp named: “Precomp1”. It also creates another composition within “Precomp1” named: “Item 1”. I’m trying to then automatically add an expression to the opacity property for “Item 1.” Here is my current code:

  var MasterComp = app.project.activeItem;
  var Precomp1 = app.project.items.addComp("Precomp1", 1920, 1080, 1, 60, 29.97);
  MasterComp.layers.add(Precomp1);

  var Item001Comp = app.project.items.addComp("Item 1", 1920, 1080, 1, 60, 29.97);

  Precomp1.layers.add(Item001Comp);

  Any ideas?

  Thank you!

  Paul Connors replied 9 years, 6 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  November 1, 2016 at 4:45 pm

  Like this, I think:

  var MasterComp = app.project.activeItem;
  var Precomp1 = app.project.items.addComp(“Precomp1”, 1920, 1080, 1, 60, 29.97);
  MasterComp.layers.add(Precomp1);
  var Item001Comp = app.project.items.addComp(“Item 1”, 1920, 1080, 1, 60, 29.97);
  var myLayer = Precomp1.layers.add(Item001Comp);
  myLayer.property(“Opacity”).expression = “75”;

  Dan
• 

  Paul Connors

  November 1, 2016 at 6:17 pm

  Hi Dan. That’s fantastic! Thank you very much. I’m able to get it to work with a simple expression like “75” or even “wiggle(2,50)” but I’m struggling to add a more complex expression to that opacity property. I have an expression from another project I’m trying to incorporate here. That working expression looks like this:

  C = comp("Master");
  ctrl = C.layer("Controls").effect("Slider Control")("Slider");
  L = C.layer(thisComp.name);
  val = Math.round(ctrl.valueAtTime(time+L.startTime));
  if (val == index) 100 else 0

  
  Do you know how would go about incorporating that to opacity expression help you offered above?

  Thanks!

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