• Adobe After Effects Expressions

  Controlling parameters of multiple expressions from a “master” expression or layer

  Posted by Shawn Marshall on November 22, 2011 at 10:35 pm

  Hi:

  I’m using this expression on 60 layers to mimic aerial expression, making each layer dissolve out as it gets farther from the camera (thank you Dan, et. al.):

  L = thisLayer
  P = L.toWorld(L.anchorPoint);
  dist = P[2] – thisComp.activeCamera.position[2];
  linear(dist,20000,60000,100,0)

  This works great, but now I want each layer to start at, say, 85% opacity. The brute force way for me to revise this would be to change the 100 to 85 and copy and paste this new expression into the 59 other layers. There must be a more efficient way to do this. I’m guessing there’s a way to assign a variable for each of the four parameters in this aerial perspective expression and assign a value to those parameters in a different expression or something so that by changing the values in that one “master” expression it will ripple through all 60 layers with the aerial perspective expression. I think I know how to set up the variables in this aerial perspective expression, but I’m not sure how to point those to another expression or layer or how I assign the values I want in that “master” expression.

  Any suggestions are appreciated.

  Thank you.

  Shawn Marshall
  Marshall Arts Motion Graphics

  Shawn Marshall replied 14 years, 9 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  November 22, 2011 at 11:30 pm

  You could link any variables you want to slider controls on a master control layer. You’d still have to update all the expressions, but actually that’s pretty easy if you select the property with the updated expression, then Edit > Copy Expression Only, select all the other layers, and Edit > Paste. It’s pretty fast, even with a lot of layers.

  Dan
• 

  Shawn Marshall

  November 23, 2011 at 2:29 am

  Hi:

  Thanks for the quick reply. I figured sliders and my friend the pick whip would serve me well, and they did. I never noticed the Copy Expression Only command. That should really come in handy in the future.

  Cheers.

  Shawn Marshall
  Marshall Arts Motion Graphics

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