Adding a bone without wrecking the rig

[joepal]

Ok, I must be kind of daft, but I can't make this work. I know there's something I'm missing.

So I want to have a character who can wiggle his ears.

Step 1, import a vanilla character

http://www.jwp.se/files/rig1.png



Step 2, do add->armature->single bone, named LeftEar.

http://www.jwp.se/files/rig2.png



Step 3, assign a vertex group called LeftEar

http://www.jwp.se/files/rig3.png



Step 4.... Well, now I get stuck. What I attempt here is to somehow parent the bone to the mesh (or whatever way one describes it), ie "set parent to -> armature deform -> automatic weights". I don't even know if this is conceptually a good idea, but let's try.

http://www.jwp.se/files/rig4.png



Step 5, notice disastrous results. The whole mesh moves outside the original rig, and ear bone hangs alone in the air.

http://www.jwp.se/files/rig5.png



Anyway, if entering pose mode and manipulating the bone, random parts of the mesh move. Not the ones that I wanted, but still...

So question is, how do I add a new bone to the MHX rig without wrecking everything?

[ThomasL]

Yikes! Having two armature modifiers on the same mesh is asking for trouble.

Select the armature. Toggle into edit mode. Add the ear bones and parent them to the head. The simplest way is to extrude symmetrically (Shift-E?) a pair of bones from the head bone, unselect connected, and move the left one into position (the right should follow). Then add vertex groups to the mesh, and remove (or reduce the weights) of the head group. That can be done with X symmetry, too.

So you don't have to add any new parenting or armature modifiers - just add bones to the existing armature.