• Adobe After Effects Expressions

  Bounce at regular interval

  Posted by Aharon Rabinowitz on July 18, 2007 at 9:07 pm

  Hi there-

  Can anyone help me with an expression that makes a layer bounce at a constant pace. I want to time a bouncing layer to the beat of some music, so the expression would need to be minutely adjustable.

  The bounce part needs to be a linear keyframe and the zenith of the actual bounce needs to be an ease in/out. I will animate the position X by hand – possibly with a null, if the expression does not alow the layer to have its position keyframed.

  So basically, like a karaoke ball standing in place.

  Make sense?

  Thanks.

  Aharon

  —————————————-
  Aharon Rabinowitz
  arabinowitz(AT)yahoo(DOT)com
  http://www.allbetsareoff.com

  —————————————-
  Click the link below to subscribe to the Creative Cow After Effects Podcast, and get free AE video tutorials:

  https://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=111087911

  Dan Ebberts replied 18 years, 10 months ago 2 Members · 3 Replies
• 3 Replies

• 

  Dan Ebberts

  July 18, 2007 at 9:44 pm

  Aharon,

  If you keyframe one cycle of the bounce with three keyframes, add a slider to set the bounce period and another for the bounce start time, something like this should work:

  period = effect(“period”)(“Slider”);
  bounceStart = effect(“start”)(“Slider”);

  t = ((time – bounceStart)%period)/period;
  valueAtTime(linear(t, key(1).time, key(3).time))

  You’ll probably want to reduce the slider ranges to give you finer control.

  Dan
• 

  Aharon Rabinowitz

  July 19, 2007 at 7:18 pm

  Thanks. I’ll give this a shot.

  So my understanding is that the distance between the keyframes doesn’t matter, right? The expression is what controls the actual timing?

  —————————————-
  Aharon Rabinowitz
  arabinowitz(AT)yahoo(DOT)com
  http://www.allbetsareoff.com

  —————————————-
  Click the link below to subscribe to the Creative Cow After Effects Podcast, and get free AE video tutorials:

  https://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=111087911
• 

  Dan Ebberts

  July 19, 2007 at 7:39 pm

  Yup, that’s how it should work.

  Dan

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