• Adobe After Effects Expressions

  Opacity Control via a single slider

  Posted by Nick Guth on March 7, 2009 at 10:34 am

  Hey all,

  I must be tired, but I have a question.

  I am creating a preset of a bunch of effects (to hand out to various members on the project). The idea is so they can drag n drop the preset onto the footage and be done with it.

  I was trying to set it up where I could have an expression control affect the layers opacity that it was dropped onto, without having to ADD an expression to the layer itself, making less work for other members.

  So maybe adding an expression to a slider and making it change the opacity value or something?

  Is this possible?

  Thanks!!

  Filip Vandueren replied 17 years, 5 months ago 3 Members · 4 Replies
• 4 Replies

• 

  Filip Vandueren

  March 7, 2009 at 1:44 pm

  Can’t be done,
  the expression has to be added to the actual property you want to change.

  There should be no problem in adding an expression to an animation preset however.
• 

  Kevin Camp

  March 7, 2009 at 6:49 pm

  [Filip Vandueren] “There should be no problem in adding an expression to an animation preset however”

  what filip is saying here, is that you can add a slider control, then add an expression to the opacity to link the opacity to the slider (just use the expression pick whip and drag to the slider value). your opacity expression would look something like this:

  effect(“Slider Control”)(“Slider”)

  then you can select the layer’s opacity property and the slider effect and choose animation>save animation preset. that preset (with expression and all) will then be available to easily apply whenever needed.

  you could also use the transform effect, which has opacity control as a parameter, without needing to link the layer’s opacity with an expression.

  Kevin Camp
  Senior Designer
  KCPQ, KMYQ & KRCW
• 

  Nick Guth

  March 7, 2009 at 8:38 pm

  Thanks for responses. I knew I could link the expression to the slider control, but when I attempted to “Save Animation Preset” and apply it to a different layer – the expression attached to the layers opacity did not come with it.

  I’m trying to streamline the process so that any other artist doesn’t have to apply the expression to the layer.

  I’ll try again later this evening!
• 

  Filip Vandueren

  March 8, 2009 at 8:34 pm

  Just make sure the Opacity parameter is selected in the left column in the timeline, then save preset.
  Should work fine with expressions.

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