Inserting key affects IPO curves

While working on a walk cycle, I found it helpful to let the IPO curve extend past the end of the cycle, as well as having a curve lead into the cycle from before the first frame. But in order to make it cyclic I need to clip off those parts of the curve by inserting a keyframe and using the Constant Interpolation…

The problem is that inserting the frame affects the shape of the curve (see pic below). Is there any way to avoid this? I know I can use the handles to reshape it, but this often seems to create more of a mess.

Steve S.

I’m not sure if preserving the shape of an IPO curve, while adding keys is possible. It seems to me the IPO’s shape is always going to be changed by inserting more keys, unless there is some advanced feature I’m not aware of.

Like you said, using handles to tweak the curves manually would work, but may be a little tedious. There may be another way to do what you want.

Can I ask why you need those extra keys outside of the walk-cycle range?

Thanks for responding. The pics below show an example. It’s the QuatY curve for the Torso bone rotation from the AT-ST I’m working on. In order to give a sense of great mass and inertia, the rotation continues a few frames past the “contact” keyframe.

The green line marks the end of the walk cycle, but the low-point of the curve occurs a few frames after that. So it’s easier to continue the curve beyond the green line, then come back and clip it by inserting a key. But as I mentioned, that ends up distorting the curve.

Steve S.

I think I know what you want to do. I remember having a similar problem when I was making my first walk cycle. I wanted the follow-through of the arm and wrist to occur after the main action, and was wondering how it could fit within the walkcycle range.

A few points to clarify first:

  • I mirrored the first key in order to get the flip pose.
  • I copied an exact duplicate of the first key to the last frame.Therefore:
  • First and last frame were identical.If I remember correctly this is what I did. The flip pose is easy. You can stagger the follow-through action a few frames after as usual. As for the first and last keys which are essentially the same (remember only one gets shown) place the follow-through for the last key just before the first key. Here is a diagram of what I mean.

/key1 # # -------------------- key2 # # -------------------- key3/

/ = start and end of walk-cycle

= follow through keys

This may not have been the best method but it seemed to do the trick for me. It’s a little bit of a mind bender at first, but just remember anything that would normally follow the last key, goes instead after the first key.

Hopefully I understood your question correctly :). Let me know if I didn’t, or if something is not clear in my explanation. good luck!

I need to fire my editor ! :smiley: The above should have read:

…place the follow-through for the last key just after the first key

I wanted the follow-through of the arm and wrist to occur after the main action,

That’s exactly the type of thing I’m after.

I suppose if I wait to do the stagger after I’ve already done the Extend: Cyclic, then I could avoid adding the keyframe at an odd spot on the curve. That should help. Thanks.

Steve S.