HORRIBLE bug regarding bones

If you need the file, here.


The bug: I animated the mainmover bone’s rotation (the one that sticks out of his ass) and changed the IPO curve type to cyclic extrapolation. Watch the atrocities which follow. The bone slows and comes to a stop though the curve shows it should continue.
From then on, all animation is impossible. After creating this bug, you can’t fix it by changing the curve back to constant and bezier, and moving the timeline back and forth, you can definitely see it’s a bug. Move it forward, it will play the animation (incorrectly), move it back, and it won’t move at all until it reaches frame 1. This really messes up the animation process.

I downloaded the blend file and animated the rotation of the bone in question. I changed the IPO to cyclic extrapolation and did not encounter any errors.

I am not sure how your error came about, but have you tried appending the character & rig to a new blend file? Maybe try re-making the main move bone.

I have seen some strange bugs before. A friend of mine actually managed to delete the 3D cursor in a much earlier version of blender.

It sounds like the bones are actually doing what they should. Bone rotations are currently evaluated with quaternions, which makes it very difficult to rotate them infinitely. There are explanations and examples of quaternions in this thread (including an example by Vertex Pusher on how to rotate them infinitely - which is pretty mind boggling! lol :)).

I don’t experience the bug you describe with the timeline… but it may just be that the bone rotates suddenly, is that it? Quaternion rotations are weight based… so increasing the value in one axis will only make it face that direction ‘harder’. So when you move back, it takes awhile to ‘unwind’ at which point it will rotate seemingly very suddenly.

Are you telling me there’s no way to rotate a bone at a constant speed?!

And see this blendfile, it doesn’t even play the same way each time you animate it, that has to be a bug.


BUG.blend (126 KB)

No, I said it was difficult, and that an example was provided in the thread I linked to.

The file you provided works just fine if you key all of the channels, which actually makes sense (if you don’t key W, the curves have no starting position). Please take the time to read the quaternion rotations thread I ilnked to previously to better understand how they work.


not_a_BUG.blend (126 KB)

It still slows down and comes to a stop in the file you provided.

Yes, as I mentioned, that is how they work. Please take the time to read the thread I provided.

It’s just a thread about how confused another user is with quats. I really want to be able to switch them to regular XYZs, because right now I can’t even rotate a bone 360 degrees, it always comes to a stop before then.

Look, I’m really not interested in fighting with you about nothing. The thread, as I mentioned, has an example of rotating a bone infinitely with quaternions, which is what you seemed to be asking how to do.

And yes, the thread started with a question, but then received answers and explanations. Please cool down, nothing is wrong with quaternions they are just a little tricky to understand. If it’s any comfort 2.5 is supposed to support Euler rotations on bones as well as Quaternion.

Here is a technique to rotate bones using Euler rotations in the meantime (until 2.5). However, it is so impractical for character animation I just didn’t think it was worth mentioning.