• Adobe After Effects Expressions

  Smoothing the rotation while using auto-orient

  Posted by Ben Jaffe on April 25, 2008 at 3:27 pm

  Hi everyone!
  I’m working on a series of animations demonstrating bicycle maneuvers. They are all from a top view, and I’m really ust animating sprites. I’ve set the bike to auto-orient, but it looks strange when the bike hits a keyframe (and goes from moving straight to curving), it doesn’t smooth into the rotation like I want it to.

  I’ll put it another way for any math people:
  When the bike hits a keyframe, going from moving in a straight line to moving in a curve, the bike’s rotational velocity jumps from 0 to some positive value. I want it to smooth from 0 to the positive value.

  Now there are two ways I can see doing this. One is to tweak the position keyframes so the rotation velocity does not jump. I have had no luck with that at all. The other is to smooth the rotation with expressions. How can I do this? I already have code that calculates the biker’s rotation (since auto-orient is on). I’d love to calculate an offset for the first 5 or 10 frames which will smooth the rotation by cancelling the change in rotation out to lesser and lesser degrees through the 5 or 10 frames. In other words, kinda preemptively ramping into it.

  Thanks in advance for any and all help you can offer. This one has been driving me mad!

  Ben Jaffe replied 18 years ago 1 Member · 0 Replies
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