I have been working with Blender for about a year almost exclusively to animate 3d models for games. I absolutely love it, save for the entire flow of action strip + NLA. The moment I think I understand fully what is going on and how to operate it, something tweaks out and wrecks my progress.

To put this in a more cogent question form: does anybody have any idea why, when, sometimes I load an action, and then go and load a different action, the two actions' influences will sometimes affect the each other and change the action output, as if it is adding a little something? And then it will transpire that sometimes an action can become sort of permanently distorted when I go back and try to load it after having first loaded other actions into the field?

I'll give an example. I have a character with several animations of him doing things. On a couple of those, he is doing things in the opposite direction than most of the other animations. So if I, for example, load the base action which is a T-pose sort of thing to set a clean slate (??? this seems to work like that sometimes), and then load an animation walking in the normal direction, fine. It works. Then I load another action which has the character looking opposite the typical direction. Fine, that works (actually it doesn't in all cases but let me continue). Finally, loading the exact same second animation walking in a normal direction has him WALKING THE COMPLETE WRONG DIRECTION after I loaded the third action. Mind you, the keyframe button is off and I am not keying anything. (This is all on top of a Rigify rig generated from Blender.)

Finally, in this particular case if I reopen Blender and reload the scene, the now-faulty animation is reverted back to its ok form.

What the hell is going on here? The animations in question are stashed animations, so I understand that the changes are being stored if they are made, but where am I even making changes? It just seems like the action field has a mind of its own, slipping in influences from here and there no matter how painstakingly careful I try to be to keep animations separate. I even have an animation which is permanently damaged from this influence slip and I don't know how to fix it besides just re-animating it. I've tried going in a keyframing IK/FK influences for each of the animations in question and that doesn't do anything to fix it.

And before someone asks, when I run into problems I am making sure that no NLA strips are keyed up on top of the current action which would throw it off. They are just pure stashed actions with nothing running on top of them. It has taken me a very long time to digest the roles of the action editor (or current action) vs. the NLA vs. stashed actions, and this problem of ... just animation influence popping out of the Blender ether and bombing my animations is still something I cannot grasp. Is there another aspect to the file structure that I am missing?

Somebody please help, my liver cannot take more punishment.

  • 1
    $\begingroup$ When you switch actions, anything not animated by the new action gets left with whatever value it had before the switch (eg. if the last action animated it, it will be whatever value the last action had on the current frame). So when you switch between actions that animate different things, you can get a buildup of pieces of different actions. Maybe that's what you're seeing? If you're animating pose bones you can clear all pose bone transforms to remove the influence from previous actions. $\endgroup$
    – scurest
    Sep 26 at 16:12
  • $\begingroup$ That actually explains a lot. Seems to do the trick, too. Jeez, thanks. $\endgroup$
    – Colin
    Sep 26 at 16:56

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