Body part randomly stretched during animation

[Captain Meatshield]

During an animation project, the toes on one of my characters have suddenly moved half-way up their shins. They weren't moved, or altered in anyway. It's just a single-frame jump out of nowhere.
I've been able to realign them by moving the bones back, and using a sharp keyframe (using step tangent) to set a new position, but there's still a jarring half-frame jump as the animation plays.
I'm still fairly new to SFM, so any help is appreciated.

Screenshot of the issue:
https://drive.google.com/file/d/1rv6eMVf56kXNReZPaTGdmIzUcraAIfCH/view?usp=drive_link

[Zappy]

Originally posted by Captain Meatshield:

Body part randomly stretched during animation

I'm not sure why it happened in the first place, and it's usually related to an IK rig (so why would it specifically affect the toes?) - though maybe you just accidentally had the toes selected while moving another body part once? Regardless, this is what I usually say about this issue:

This isn't necessary to know, but might still be nice to know:

When you attach or detach an IK rig script to a model, the model's current motion is "baked" into the new set of controls, so that you don't have to re-animate everything.
This only happens within the model's animation set's timeframe, though, which only extends 5 seconds before/after where the shot started/ended when you made the animation set.
Any part of time before or after the model's animation set will have the model in a "zero"-state once you attach/detach an IK rig script, with all of its new controls' positions and rotations being set to 0 instead of the intended values.
Usually, this doesn't really matter that much, as the problems lie outside the shot... but if you create keyframes in the Graph Editor and move the first keyframe or move/delete the last keyframe, (or alternatively Alt-drag on the time selection in the Motion Editor, or just extend the shot in the Clip Editor,) you may bring those "zero-state" points towards, and eventually inside, the shot, making them visible.

To fix it:

- Switch to the Clip Editor
- Double-click on the shot in question
- Extend all yellow bars in the timeline (by dragging on their edges, not by just moving the entire bars), one by one, to cover the whole shot
- Click on the curvy up arrow above the timeline to return to the normal Clip Editor afterwards
- Switch to the Motion Editor
- Move the playhead (time cursor) to the last frame before the model distortion
- Click in the timeline and press Ctrl+A to select all time
- Move the left edge of the time selection to where the playhead is (so that the time selection starts at the playhead and extends into infinity)
- Select the affected model(s) or control(s) in the Animation Set Editor
- Fully apply the procedural "Playhead" preset in the upper right area of the Animation Set Editor
- Press Enter to apply the changes

This should freeze the selected controls in place from just before the distortion, after which you should be able to continue working on the animation as normal.



To mostly avoid this in the future, just extend a shot to be much longer than you need before creating animation sets in the shot, and then shorten the shot afterwards.