Using Tuhopuu, I made a classic leg armature with a bone at the heel to direct an IK solver and another to point the foot. Then I thought that using the “follow path” constraint on the heel bone would be such a powerful tool…
Well, I was able to constraint the heel bone to a path but not to make it move either “free hand” or by starting the animation…
I guess that I dreamt too far… ?
Jean
Something like this?
Just make sure the Path has a Speed IPO, it won’t work otherwise. I haven’t had time to solve that bug yet 
Or maybe I didn’t understood your problem?
Martin
The abscence of a speed IPO was the culprit.
Check http://pages.infinit.net/bobois/patte01.zip ; this is going to become an extremely powerful tool for character animation, making it possible to quickly make complex animations very fluid and easy to control.
Bravo Martin !
How to include it into the workflow of the Action and NLA windows though ?
Jean
You use this to control general motion and use the NLA to control added motion. For example, you could have a robotic arm that moves on a path. You’d use the path to control the position of the arm, and the NLA to make the arm grab something or wave or …
Martin
Well, yes, that would be simply overlapping some actions (grabbing, scratching one’s nose…) with the path animation. What I’d really like to do is to make the path-animation that “IK_solves” the character into an action itself so I could manipulate it into the Action and NLA windows…
Jean
You could do that by baking the action (using the Bake button). That would create keyframes correspoding to the constraint motion, so you could then delete the constraint and reuse the action in the NLA.
It would be nice if Baking would have a fequency setting… uhm maybe I’ll look into that.
Martin
You made me perplexed there for a few seconds since the simple fact of having the constraint “follow path” doesn’t create any action. But it was enough to insert a set of loc/rot keys at frame 1, the start of the path_anim and another set at frame 100 and then bake.
It would be nice if Baking would have a fequency setting… uhm maybe I’ll look into that.
Martin
“Nice” for what purpose ? Is it that the baked actions are too demanding for the machine ? It makes for a smaller file for sure though with now 100 Kb instead of the former 43 Kb of the non baked version.
Anyway, this is so much fun : I can’t wait to see what I can do for some interactive presentation in real time that I have in mind.
Here’s the baked version for those who are curious : http://pages.infinit.net/bobois/patte02.zip
Thanks Martin.
Jean
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No no, it’s not too demanding for a machine, but a frequency based baking could be used to keyframe just one frame out of 3. The interpolation would do the rest. It makes a cleaner Action block that way IMHO.
Anyhow, a more intelligent baking process would remove uneeded keyframes (like for a chain of bones that are controled only with an IK, that would mean only one keyframe instead of one each frame).
Martin
[quote=“theeth”"]
Yes but that would depend on the shape of the resulting IPO ; for example, a broken line (ligne brisée) requires a key at each change of direction. The matter wouldn’t be so simple.
Strangely, I noticed that the baked action is translated to a set of IPO that are of the bezier type : since there’s a key for each frame a linear IPO would do as well (that’s what I did in the second example). Would it be faster to compute ?
Jean
OK, while we are on the subject of simplification, once the action has been baked, it is possible to get rid of the path and the “follow path” constraint put on the heel (talon) bone, obviously, but also of the tigh (cuisse), leg (jambe) and foot (pied) channels. Heel and toe must remain as well as their constraints…
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This would mislead the reader. Indeed I had the best success by getting rid of the toe (orteil) and heel (talon) bones and all constraints and keeping the tigh, leg and foot. Understand that this is much a WIP as well as a learning process for myself.
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OK, time to sleep.
Night.
Jean
Faster yes, but not by much.
Martin