Control a long chain of bones using constraints...

[heyvern]

This came up in another thread and i thought I should put it here... this may have already been done, but I am doing it again.

Basically it is a way to have a whole bunch of bones in a chain for smooth deformation of a mesh without having to key frame all the bones.

One chain has many bones and directly distorts the mesh, the secondary control chain has fewer bones and controls the mesh bones with "blended" rotation constraints... fan bones basically... but... uh... not fanned.

In the example below I am controlling about 6 "back" bones (spine neck head) with just 3 control bones. Take note how I moved the control bones around on different frames if they get in my way. Since the translation has no impact on anything you can put them anywhere.

http://www.lowrestv.com/moho_stuff/bone_rig2.mov

http://www.lowrestv.com/moho_stuff/bone_rig.zip

This is fantastic for tails or tentacles and hair, like ponytails.

-vern

[rylleman]

Hey, that zipfile seems to be broken, it crashes windows explorer every time I select it.

[heyvern]

Well... I had no trouble with the zip before uploading (I test it to make sure it works okay). And I downloaded fine just now. I don't know what may be wrong.

I uploaded a new one just in case. I have had some trouble with file permissions in the past. Files that are locked for some reason. This one seems to be okay.

Here is the plain .moho file as well...

http://www.lowrestv.com/moho_stuff/bone_rig.moho

-vern

[bupaje]

That is a cool sample. Haven't played with control bones much. Time to revisit.

OT: As I looked at your example I was thinking a cool feature might be the ability to color bones in AS to match the control bones. Tell at a glance who controls what.

[heyvern]

Actually, I usually just hide the controlled bones. I don't need to see them anyway if something else controls them, plus they give me a clearer picture of the animation.

And if they are hidden... I won't accidentally click on them and have a bunch of useless key frames.

Colorizing bones... that would be great though for many other reasons for me.

I have a short scene with... er... pig legs? Two sets sticking out from behind a barn.

Two different pigs, but they are in the same bone folder... I am constantly grabbing the wrong set of leg bones... they are... intertwined if you catch my drift.

Please don't ask. Not my idea. It embarrasses me as well. I have to cover my eyes when I do a preview render... of course this makes it hard to see how the scene is going.



-vern

[j0llyr0ger]

An extension of this idea for something like tentacles, elephant trunks, or even a very flexible spine is to make a chain of bones (a series of bones end to end with each parented to the one before it) with each one constrained to the rotation of a single control bone.

To tune the curliness of the appendage (tentacles generally are more bendy at the ends than at the roots) the amount of the constraint can very on each bone in the chain. Say 1 for the root bone of the chain, 1.2 on the next one, 1.4 on the next one etc.

This technique makes the animation of something like an octopus MUCH easier than rotating each bone.