• Adobe After Effects Expressions

  Opacity swoosh across multiple solids.

  Posted by Nico Jones on June 18, 2009 at 2:38 pm

  Hi guys,

  I’m trying to create an effect with a grid of 50 solids arranged in 10 columns of 5.

  Basically, I want them all to be completely invisible to begin with, then from top left to bottom right (in horizontal lines, if that makes sense), I want them to flash on and off smoothly in sequence, but in an overlapping fashion.

  So solid A goes in opacity from 0% to 100% to 0%, but as it gets to, say 50% opacity on the way up, Solid B gets to 20%. If that makes sense!

  I’d like to do it with as few keyframes as possible, but could never quite figure out the ‘take opacity from the layer above and etc etc.’ part of expressions and am now in something of a hurry to achieve this effect.

  Many thanks,

  Nico

  Nico Jones replied 17 years, 2 months ago 2 Members · 4 Replies
• 4 Replies

• 

  Dan Ebberts

  June 18, 2009 at 3:17 pm

  You could start with an opacity expression like this. Tweak the first two parameters and see if it gets close to what you’re after. It should sequence the layers with overlap.

  transTime = 1; // duration of 0 > 100% > 0 transition
  delayPct = 15; // delay percentage for next layer

  delay = transTime*(delayPct/100)*(index-1);
  if (time < delay + transTime/2){ ease(time,delay,delay+transTime/2,0,100) }else{ ease(time,delay+transTime/2,delay+transTime,100,0) } Dan
• 

  Nico Jones

  June 18, 2009 at 3:33 pm

  Hi Dan,

  Thanks for that,

  I’ve applied it to a solid’s opacity but it doesn’t seem to react to any change in the opacity of the layer either below or above it. Is there an obvious step I’ve missed out?

  Thanks,

  Nico

  Nico J BB
• 

  Dan Ebberts

  June 18, 2009 at 3:39 pm

  You would apply it to each layer. The expression responds to its position in the layer stack. This will sequence all the layers, but I’m starting to suspect that you want multiple rows going at the same time. Is that correct?

  Dan
• 

  Nico Jones

  June 18, 2009 at 3:46 pm

  Nope, that was exactly what I was after!

  Thanks alot – definitely gonna be using that one again!

  Nico J BB

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