• Adobe After Effects Expressions

  Question regarding randomSeed()

  Posted by Jeff Holcomb on April 17, 2016 at 4:35 am

  As I understand it, having a seed as a constant, like randomSeed(3), should generate the same set of random numbers. However, I’ve put this expression into a shape layer’s position and duplicated it, and it creates two shapes that randomly jump around, but not in unison with eachother:

  seedRandom(3,false);
  x = random(-10,10);
  Y = random(-10,10);
  [x,y];

  Because both shapes have the seed being set to 3, shouldn’t they have the same set of random values? Is there something I’m missing?

  Dan Ebberts replied 10 years, 4 months ago 2 Members · 3 Replies
• 3 Replies

• 

  Dan Ebberts

  April 17, 2016 at 6:23 am

  Behind the scenes, the layer ID somehow gets factored into the seed, so each layer exhibits different random behavior.

  Dan
• 

  Jeff Holcomb

  April 17, 2016 at 6:42 am

  Hi Dan, thanks for the response. So does that mean that putting any value into randomSeed() is pretty much pointless then, whether it’s a numerical value or ‘index’?
• 

  Dan Ebberts

  April 17, 2016 at 6:57 am

  It does affect the random sequence for that layer.

  If you need to correlate the random behavior of multiple layers, you can sometimes do it by doing the random calculation in a single expression in a central location (slider, point control, text layer, etc.) and “publishing” the result for the randomized layers. The specifics would depend on what you’re trying to do exactly.

  Dan

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