• Adobe After Effects Expressions

  Controlling shape opacity with an expression

  Posted by Neal Strydom on October 8, 2018 at 8:45 am

  Hi guys.

  I’m busy with an animation for a client, that relies heavily upon the expression for sampleImage()
  I’m using the expression on Evan Abrams’ youtube, where the shape’s size or scale is connected to a control layer via the following expression:

  sourceLayer = thisComp.layer(“gradientControlLayer_comp”);
  sampleSize = [1,1];
  samplePoint = transform.position;
  colour= sourceLayer.sampleImage(samplePoint,sampleSize);
  x=colour[0]*16;
  [x,x]

  Now I want to see what the possibility would be, to link this to an opacity property, instead of a size or scale.
  I tried adjusting the expression myself, but failed horribly and I would like to ask if any of you would be bale to assist me?

  The core of this enables me to control the shape of multiple objects, using a gradient animation in a comp as a control layer. I would like to do the same for opacity, if that is possible ?

  Thanks!
  Neal

  sourceLayer = thisComp.layer("gradientControlLayer_comp");
sampleSize = [1,1];
samplePoint = transform.position;
colour= sourceLayer.sampleImage(samplePoint,sampleSize);
x=colour[0]*16;
[x,x]

  Dan Ebberts replied 7 years, 9 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Dan Ebberts

  October 8, 2018 at 1:09 pm

  Try replacing the last two lines with this:

  colour[0]*100

  Dan

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