• 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, 4 months ago 1 Member · 0 Replies
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