• Adobe After Effects Expressions

  Control layer opacity with “Master Null” whilst respecting existing keyframes?

  Posted by Wick Van den belt on September 9, 2016 at 10:04 am

  Hi all!

  I was trying to achieve something, however I haven’t found a good solution for it.
  I have a Pre-comp (Let’s call it “Overlay”), now I would like to control it’s opacity with a checkbox with the master null (e.g. Layer on/off).. -However the layers in the precomp already have opacity keyframes (going from 0 – 50).

  So in the master comp I would like to be able to use the switch to control the on/off for this layer (basically by changing it’s opacity between 0 – 50) but in that scenario the keyframes are no longer respected.

  I have created a null called “UNIVERSAL CONTROLLER” with a checkbox called “” and I use the following expression on the Overlay-layer :

  cb = comp(“Universal Controller Video”).layer(“UNIVERSAL CONTROLLER”).effect(“Overlay”)(“Checkbox”);
  if (cb.value) 100 else 0;

  Is there something I could do with the expression to respect the existing keyframes, or is there a workaround that might do the trick?

  I hope I’ve explained the idea well enough to understand 🙂

  Thanks a lot!

  cb = comp("Universal Controller Video").layer("UNIVERSAL CONTROLLER").effect("Overlay")("Checkbox");
if (cb.value) 100 else 0;

  WickieMedia.net

  Wick Van den belt replied 9 years, 11 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  September 9, 2016 at 11:02 am

  Try changing the last line to this:

  if (cb.value) value else 0;

  Dan
• 

  Wick Van den belt

  September 9, 2016 at 3:22 pm

  That was it!
  Thanks so much, you’re really THE expression guru 🙂

  WickieMedia.net

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