• Adobe After Effects Expressions

  creative random flickers

  Posted by Adam Chen on February 3, 2012 at 1:34 pm

  I want to craeative some random flickers，and I can control the flash speed.
  so I write this Expression，

  position：

  tot = linear(time,0,4,1.5,8);
  r = random(-4,1);
  c = clamp(r,0,1);
  wiggle(tot,700*c)

  brightness:

  len = length(effect(“Optical Flares”)(“Position XY”),effect(“Optical Flares”)(“Center Position”));
  k = random(0.8,1.4);
  if(len>100) {
  120*k;
  }else{
  0
  }

  It can work but not so perfect,cause it`s position bases on random wiggle.and falsh speed also hard to control.
  Did you have any better ideas?

  Adam Chen replied 14 years, 2 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Immanuel Morales

  February 12, 2012 at 4:44 pm

  I always end up telling people the same thing when it comes to controlling expressions: use the expression controls in the effects and presets and plug your variables into that. so for instance..

  speed = thisComp.layer("whichever layers you'll use").effect("Slider Control")("Slider");
amplitude = thisComp.layer("same layer as above").effect("Slider Control 2")("Slider");

  tot = linear(time, 0, 4, 1.5, 8);
r = random(speed, amplitude);
c = clamp(r, 0, 1);
wiggle(tot, 700*c)
• 

  Adam Chen

  February 15, 2012 at 7:00 am

  Thanks for you reply，I will try it.

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