• Adobe After Effects Expressions

  Shuffle layers order while keeping track mattes link??

  Posted by Antoine Dupont on December 27, 2020 at 8:41 pm

  app.beginUndoGroup("Randomize");
  var myComp = app.project.activeItem;
  var n = myComp.numLayers;
  var myLayers = [];
  var myIdx = [];
  for (var i = 1; i<= n; i++){ 
      myIdx[i-1] = i; 
      myLayers[i-1] = myComp.layer(i); 
  } 
  var idx;
  var temp; 
  for (var i = 0; i < myIdx.length; i++){ 
      idx = i + Math.floor(Math.random()*(myIdx.length - i)); 
      temp = myIdx[i]; 
      myIdx[i] = myIdx[idx]; 
      myIdx[idx] = temp; 
  } 
  for (var i = 0; i < myIdx.length; i++){ 
      myLayers[myIdx[i]-1].moveToBeginning(); 
  }
  app.endUndoGroup();

  This code shuffle the order of the layers.

  How can I shuffle the order of track mattes without breaking their link?

  Thank you!

  Filip Vandueren replied 5 years, 8 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Filip Vandueren

  December 28, 2020 at 9:19 pm

  Like this:

  app.beginUndoGroup("Randomize - keep Mattes");
  var myComp = app.project.activeItem;
  var n = myComp.numLayers;
  var myLayers = [];
  var myIdx = [];
  for (var i = 1; i<= n; i++){ 
      if (myComp.layer(i).isTrackMatte) {
          continue
      }
      myLayers.push(myComp.layer(i)); 
  } 
  while(myLayers.length) {
      randomIndex = Math.floor(Math.random()*myLayers.length)
      l=myLayers.splice(randomIndex,1)[0];
      if (l.hasTrackMatte) {
          myIndex = l.index;
          l.moveToBeginning();
          // matte now has the same index as it's target had beofre it was moved up
          myComp.layer(myIndex).moveToBeginning();
      } else {
          l.moveToBeginning();
      }
   }
  app.endUndoGroup();

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