• Adobe After Effects

  Changing color of a light randomly with expressions

  Posted by Helgi Johannsson on August 28, 2005 at 9:12 pm

  Hi,

  I’m somewhat familiar with expressions, but this leaves me with no clue. How can I randomly change color of a light with expressions. Change maybe every half a second or so. And I would certainly prefer only to use 5-6 colors.

  Is this possible?

  Helgi Johannsson replied 20 years, 8 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  August 28, 2005 at 10:27 pm

  In expressions, color is represented as an array of [red,green,blue,alpha] where the values have to be between 0 and 1. (Leave the alpha value set to 1 – it doesn’t do anything but it has to be there. So this would be one way to change the color at random every half second:

  
  
  period = 0.5; // change color every .5 seconds
  colors = [[1,0,0,1], // red
            [0,1,0,1], // green
            [0,0,1,1], // blue
            [1,0,1,1], // magenta
            [1,1,0,1], // yellow
            [0,1,1,1]] // cyan
  
  seed = Math.floor(time/period);
  seedRandom(seed,true);
  idx = Math.floor(random(colors.length));
  colors[idx]
  
  

  Dan
• 

  Helgi Johannsson

  September 2, 2005 at 4:46 pm

  Thank you very much Dan, you are incredible 🙂

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