How do I add new bones without losing existing weights?

I have a lovely mermaid model, already rigged. I just need to add a couple additional bones to make certain parts animatable that were like rigid plastic before.

So I used the Joint tool to add two additional bones. I was using the top-down view so they appeared initially down on the XZ plane, but I dragged them up into position, and carefully positioned them where I think they should go.

newbones.png


Then I selected the Skeleton tag on torso mesh, and dragged the two new bones into the joint list. Of course nothing is attached to them yet. So I switched to the Vertex Weight tool, in Add mode, selected one of the new bones in the list, and carefully painted a bit of the mesh that should attach to that bone. But as soon as I release the mouse button:

wtf.png


The painted vertices shoot down towards the floor. Weirdly, they do not respond to movements/rotations of the new bone. Also, Undo does not undo the damage.

What has gone wrong here? How do I add a couple of new bones without losing the excellent rigging already there on the fingers, etc.? I confirmed that if I use the Auto-weight function to rebind the mesh, then the new bones work; but all the other weights are lost (i.e. the auto-weight function produces a poor result compared to the previous weights).
 
I'm not good at rigging, but I'm afraid that if you add new bones, you will need to bind again before using vertex weight. (But I can be wrong) I know that you don't want to bind again because it won't be as good as it was. I know the problem and haven't found a solution yet. I would be grateful if someone had one.
But if you only want to move the breasts, you could perhaps solve that with the morph tag.
 
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I agree with Lydia, I don't think you can add bones without rebinding but the Morph Tag
can be used for simulating muscle flexing so that's what I would try.
 
Ugh. This is really frustrating. Is there really no way to limit the rebinding to just a subset of the model?

Other things I've tried:

  • Duplicate the mesh; rebind the joints; copy just the section of the mesh I want to be affected from that one into the original mesh. But nope, when I paste the copied faces, they come in with no vertex weights at all.
  • Rebind the mesh, copy the area of interest, and attempt to undo the rebinding. Nope, not undoable.
  • Rebind the mesh, copy the area of interest, revert to the last saved version, and paste. Again no, they come in with no weights.
It seems that vertex weight data is simply not included on the clipboard. And so far I can find no way to restrict rebinding to just one bone, OR to just one area of the mesh.

This is astonishing to me, and about enough to make me give up on Cheetah3d. For me this comes up all the time; I get a model rigged beautifully and just need to add a couple of bones for the pony tail, or long coat, or whatever. This should be a basic operation, not a source of such frustration. And no, I can't work around it with blend shapes.

Is there maybe some way to work around it with scripts? Some way to save off all the vertex weights for all bones except the one or two new ones, so I can then paint weights for those without screwing everything up?

If there really is no solution in Cheetah3d, can anyone recommend another tool that would handle this better? I'm almost ready to learn Blender, though its UI drives me insane. :(
 
Don't worry. Not only the UI will drive you insane, the rigging, too. In this case, by the way, a morph would be the normal solution (a female breast isn't like an arm that moves in a certain way and no other etc. So the morph would be the natural, logical solution, and the only one that seems natural (as a rule of thumb ... Is in reality a bone in there? Joint. Isn't? Morph. It probably has a reason the maker(s) of this model didn't include earlobe joints ...).

But you probably will not be happy with your rigged character. In any app. All tris is bad for animation. Like in "really, really bad". You should import the model with keeping the quads (or get another model).
 
I am sure this model is designed for a game engine. The tri's are a necessity. As is the bone manipulation rather than morphs.

I feel your pain Joe. I have been there myself. As stated above, I am afraid Cheetah will not do what you are asking of it.

Personally, I cannot deal with Blender. I know it is powerful but everything about it is bass ackwards. I have tried to force myself to learn it on multiple occasions and it always ends with me wanting to pull my hair out. I just do not have the time or patience for it. I would rather deal with a little weight painting than mess with that quagmire.

Old dog new tricks I guess.

You may get lucky and find a tool in blender to do what you are attempting though. If all you have to do is add a few bones and bind them to the mesh in a non-destructive way you may not have to learn or use much of Blender. You could still do all of the real work like weight tweaking and animation in Cheetah once that is done.

I wish you luck on whatever solution you find.
 
I am sure this model is designed for a game engine. The tri's are a necessity. As is the bone manipulation rather than morphs.

Even if it was used for a game engine only, the conversion to tris usually would be one of the last steps because they really are rather awkward to handle. So somewhere on a computer far away that same model sits happily all clad in quads. The question is if it's available in quads or not (well, it could be cleaned up, but ...). I don't know where he got the model from, but probably from some site as a download.

And game engines have no trouble with morphs which can be loaded and saved via fbx. But I plain don't know if Cheetah has that capability.

For all this blender would be much better suited than Cheetah, that's true. Actually it's used more and more by game artists (but I don't know if all the really good tools are free. There is meanwhile a plethora of plugins available). So I do agree, as someone who dislikes blender at least as much as you, that blender could used in that way. That's true for you and your game, too.
 
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