• Adobe After Effects Expressions

  Impossible expression

  Posted by Gerardo Morales on April 29, 2009 at 7:34 pm

  Hello fellow animators,

  I have this problem which is troubling my mind beyond sanity. I’m trying to blow up an object composed of many layers and elements. I want to use the same expression, maybe with variations (2 or 3) for all the layers in the position attribute.

  First I came up with this expression:
  
  randomfactor= random(1, 10);
  pos= 1
  neg= -1
  slider=thisComp.layer(“slider”).effect(“Slider Control”)(“Slider”);

  x= value[0]+neg*randomfactor*slider;
  y=value[1]+neg*randomfactor*slider;
  z=value[2]+pos*randomfactor*slider;

  [x,y,z]

  But it didn’t work as I wanted to, because the random function makes the animation jumpy.

  Then tried this one:

  factor= 15;
  pos= 1
  neg= -1
  slider=thisComp.layer(“slider”).effect(“Slider Control”)(“Slider”);

  x= value[0]+neg*factor*slider;
  y=value[1]+neg*factor*slider;
  z=value[2]+pos*factor*slider;

  [x,y,z]
  

  But it was to predictable and the explosion didn’t seem random.

  I think what I really need is a way to produce a random factor to use in the first equation instead of the random function, that way a random number is produced for each layer at the first frame and used for the duration of the animation instead of generating random numbers every frame.

  Anyone know of a way to produce and hold this random number? Or maybe a better solution for this effect?

  Thank you,
  Gerardo.

  Gerardo Morales replied 17 years, 4 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  April 29, 2009 at 8:14 pm

  Start your expression with:

  seedRandom(index,true);

  Dan
• 

  Gerardo Morales

  April 29, 2009 at 9:17 pm

  Worked like a charm.

  Thanks Dan.

  Gerardo

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