• Adobe After Effects

  Expression to control opacity of a layer from another comp help?

  Posted by Michael Combs on July 20, 2007 at 11:59 pm

  I’m trying to control a series of layers from another comp and I’m having a bit o’ trouble getting my idea around what I’m supposed to do.

  This is what I’m trying:

  I created a comp called “Open Houses” with a solid layer and added a series of Checkbox expression controls to it, renaming them “Property 1”, “Property 2”, etc.

  Then in the comps that I want to control, I add an expression to the opacity value – “comp(“Open Houses”).effect(“Property 1”)(“Checkbox”)*100″

  The idea, as far as I can figure, is to grab the value from the Open House Comp and the Property 1 checkbox and multiply it by 100. So, if the switch is on, then the value for the opacity is 100. If the switch is on, the value is returned as 0. That’s what I think should happen. I think I was being clever.

  This is the error I get:
  After Effects Warning: Function comp().effect is undefined. Expression Disabled. Error Occured at line 1. Comp:’property 1′ Layer: 2(‘open house info.psd’) Property: ‘opacity’

  Help?

  Darby Edelen replied 18 years, 9 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Darby Edelen

  July 21, 2007 at 2:05 am

  [Michael combs] “This is the error I get:
  After Effects Warning: Function comp().effect is undefined. Expression Disabled. Error Occured at line 1. Comp:’property 1′ Layer: 2(‘open house info.psd’) Property: ‘opacity'”

  You need to tell it what layer in the comp has the effect on it:

  
comp("Open Houses").layer("My Null Controller").effect...

  Like that =)

  Darby Edelen
  DVD Menu Artist
  Left Coast Digital
  Aptos, CA

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