Expression example: Position one layer between two others

This example expression positions and maintains one layer at a balanced distance between two other layers.

  1. Start with three layers. (See Creating layers.)
  2. Animate the positions of the first two layers in the Timeline panel. (See Motion paths.)
  3. Select the third layer, press P to reveal the Position property, and Alt-click (Windows) or Option-click (Mac OS) the stopwatch button to the left of the property name.
  4. Enter the following in the expression field: 
      (thisComp.layer(1).position + thisComp.layer(2).position)/2