• Adobe After Effects Expressions

  Undulation seamless loop

  Posted by Shannon Towell on September 11, 2020 at 8:30 am

  Hi! I’m using the Dan Ebbert’s expression for undulation (https://www.motionscript.com/expressions-lab-ae65/undulations.html), as I want my objects to look like they’re moving like a wave. I’m having trouble making a seamless loop. My composition has 5 objects using this expression, and is 3 seconds long. I’d appreciate any help you can muster, thanks!

  —–

  The undulation expression is:
  Position:

  xAmp = 3; //height of undulations (pixels)
  xFreq = .3; //undulations per second
  xSpeed = 150; //speed of wave (pixels per second)
  
  wl = xSpeed/xFreq; //wavelength (pixels)
  phaseOffset = ((position[0]%wl)/wl)*2*Math.PI;
  y = xAmp*Math.sin(2*Math.PI*xFreq*time + phaseOffset);
  value + [0,y]

  Rotation:

  xFreq = .3; //undulations per second
  xSpeed = 150; //speed of wave (pixels per second)
  damping = 15; //undulation damping factor
  
  wl = xSpeed/xFreq; //wavelength (pixels)
  phaseOffset = ((position[0]%wl)/wl)*2*Math.PI;
  theta = Math.atan(Math.cos(2*Math.PI*xFreq*time + phaseOffset));
  radiansToDegrees(theta)/damping;

  Shannon Towell replied 6 years ago 2 Members · 2 Replies
• 2 Replies

• 

  Filip Vandueren

  September 11, 2020 at 9:23 am

  the frequency of .3 doesn’t fit exactly in 3 seconds. But 0.333333 would.

  To be absolutley sure, you might want to express the undulations as 1 undulation over the entire comp’s time like this:

  xFreq = 1 / thisComp.duration; 

  (or simply 1/3 in this case)
• 

  Shannon Towell

  September 22, 2020 at 7:13 am

  Thank you very much, that worked a treat! I hope you have had a good weekend!

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