• Adobe After Effects Expressions

  Turning on and off an effect via expressions

  Posted by Tyler Paul on November 7, 2006 at 7:27 pm

  As the subject says, I want to turn on/off effects with a checkbox

  I have on the checkbox
  if(thisComp.layer(“Pen”).effect(“Pen Sketch”)(“Checkbox”)==1) comp(“Pre”).Layer(“Pen”).Effect(“Brush Strokes”).active=1 else comp(“Pre”).Layer(“Pen”).Effect(“Brush Strokes”).active=0

  The checkbox works, just doesn’t turn off the effect.

  Tyler Paul replied 19 years, 6 months ago 3 Members · 5 Replies
• 5 Replies

• 

  Tyler Paul

  November 7, 2006 at 8:20 pm

  well, I know my first problem. I expressions in a proporty can only effect that property….

  So… where do I put the expression to disable a layer? And I know active is for layers but I don’t even know if they work for effects as well…. and… boy do expressions suck… and rock…

  back to reading
• 

  Steve Roberts

  November 7, 2006 at 8:22 pm

  You can’t disable layers with expressions, but you can set their opacity to zero.
• 

  Dan Ebberts

  November 7, 2006 at 8:22 pm

  I see a couple of basic problems. First, you can’t affect a property with an expression applied to a different property. An expression can only control the value of the property it’s applied to.

  Second, an effect’s “active” attribute is read-only.

  What you could do though is apply an expression to the Brush Stroke’s Blend With Original parameter and set it to 0 or 100% based on the checkbox.

  Dan
• 

  Tyler Paul

  November 7, 2006 at 8:46 pm

  Well, dangit, that’s what I had originally and figuared there was a more correct way. So… when would active be used?
• 

  Tyler Paul

  November 7, 2006 at 8:59 pm

  Hey Dan,

  Thanks for the help. I had read your guide before I knew much about expressions and was pretty lost. I just got done reading through it again and it all made sense. Progress! It answered a lot of other questions I had too.

  Thanks again,
  Ty

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