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Thread: Rotating bones while in graph editor mode will induce positional drifting (!!)

  1. #1
    Basic Member MaxOfS2D's Avatar
    Join Date
    Jun 2015

    Unhappy Rotating bones while in graph editor mode will induce positional drifting (!!)

    This seems like a fairly new bug. I haven't been able to determine the exact cause. I first noticed it on a custom character model I'm working with, but the problem appears on everything.


    1) Create new session
    2) Create a character of your choice (e.g. QoP)
    3) Go to graph editor mode, create a key for, let's say, the index finger (easier to notice that way)
    4) move forward a few frames, create another key
    5) start rotating the finger with wild abandon. don't let go. keep rotating. you'll see the finger will start drifting away

    you'll notice here, the green arc display that grows longer and longer the more I keep rotating.

    You might think, "but Max, all these rotations, that's not a real world use case"; well, unfortunately, it does get worse. I don't know how, I don't know why, but it can get way worse, and a nice way to visualize it is to only highlight the position channels of the element you're rotating, in the graph editor, so that only they can get affected. So since you're trying to rotate into position channels, nothing should be happening, right?

    All these little positional drifts REALLY add up over time... I was wondering why my hands were starting to look weird, and then I realized, hey, I have 6 curves instead of 3 on everything... what's happening. And then it hit me.

    This happens on everything, by the way, not just fingers. Fingers are just very useful to demonstrate since they're so close to 4 of their friends, which makes spotting the discrepancy far easier.


    1) this doesn't happen when using the motion editor (F3)
    2) if only selecting the position channels, and trying to rotate them, while in motion editor mode, the selected element will vanish into thin air. (presumably at some NaN coordinates, like some old Autodesk bug that still haunts me to this day)
    3) transform mode (world vs local) doesn't seem to matter with this
    4) it happens on every single model but some are more affected by this
    5) whether a rig is applied seems to be irrelevant
    6) distance from 0,0,0 seems to not be a factor (this rules out my "floating point error" hypothesis)

    This can be worked around but the workaround is extremely tedious especially if you're, for example, animating fingers — going through 30 joints to remove their position keys is quite annoying.
    Last edited by MaxOfS2D; 04-15-2017 at 04:52 AM.

  2. #2
    Would really like this fixed too. It gets annoying having to reset to default pose every few keys.

  3. #3
    Join Date
    Jun 2017
    Why would you care?
    are you giving us flying gestures?

  4. #4
    Basic Member MaxOfS2D's Avatar
    Join Date
    Jun 2015
    Oh man haha it didn't even hit me that I was manipulating the middle finger in these GIFs, I can assure y'all that it doesn't mean anything :P

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