unwanted twisting of bones

Im sure there is a good reason, but this bone behavior seems odd to me. When I move the middle bone the two connected bones twist as they follow it. Why is that? Can anyone explain why? or else please point me to a place that does explain.

example video here

-------------edit----------------------------------

After thinking about it a little more, I realised it’s because Im not translating the bone exactly perpendicularly, but according to the view. Im thinking on a work around now, but if anyone has an idea?? Its a finger chain and Im trying to give it an arch. Unfortunately my character is not square to the x/y/z planes. Its in a slightly more relaxed (natural) pose.

Can’t load the video, but I recognize the problem. Most tuts have armature that are created as if on a cross - the exact X-plain. As you have suggested your figure is in a more relaxed pose, and will take a bit of X and Y when translating, hence roll. I think ultimately it’s better for meshes to pose and weight paint in ‘relaxed poses’ but better for armature bones [and angles] to be on a flat plain. Can’t win 'em all…

Thanks patdog, those were my suspicions. Ive re-uploaded the file, and the link works now.
Id be interested to know how other people get around this problem. Any neat tricks / work arounds people can share?

Can’t you just rotate it around the relevant local axis? R = Rotate, then Z is Global Z and ZZ is Local Z.

%<

Use the translate manipulator with the global setting in “local” mode. Or do as Fligh suggests. Since your in edit mode there are all kinds of ways to position bones where you want them.

Don’t forget to “clear bone roll angle” when your done. In fact you can just position the bones without worrying about roll, and then clearing the roll on all the bones when done.

pappy

Here is what I mean. See attached picture. My armature is in a natural pose.

Fligh-
Rotating on a local axis only works in Pose mode, not Edit.

pappy-
As above, I cannot translate/rotate/scale on local axis, even if using the manipulator gizmo.

This limitation has already been pointed out to me in another thread. See
http://blenderartists.org/forum/showthread.php?t=99319

Not being able to manipulate bones on their local axis seems a considerable limitation.
What do other people do in this situation?

Attachments


I’m at a total loss as to why and how you consider this a “situation” and a “limitation”.

Bones edit mode is just a way to get them positioned. Blender will automatically clean up the roll of the bones with ctrl n, so just grab em and stick em where they need to be.

And if you do want to rotate to do your positioning, just snap the cursor to the bones base end and rotate around it as was suggested in your other thread. Slower to do, but great for accuracy. Ignore any roll, just get the position done.

I cannot see the reason for your concern over bone roll orientation. Some programs DO require careful attention to roll for setting up constraints, but Blender allows you to assign orientation as needed.

Perhaps you could elaborate on your concerns as i have no idea what your point is from the image posted. Is this a rigging issue? or ??? From what I can see you just need to finish up by resetting your armatures center point and doing a ctrl n with all the bones selected to clean up roll.

Time to animate!

Pappy