How to animate a metal backbone?

Question

Hello i've made a cyborg (a human body with metallic parts) and i have alot of difficulties with the rigging (the metallic parts deforms when i dont want them to) and especially the backbone! there are several metallic vertebras attached to the back of the human, i made one vertebra and made an array modifier with a curve modifier How can i avoid any deformation? Is it the curve that i need to parent to the rig?

Answer 1

Ok, this is what you could try, I hope it fits with your workflow, or at least inspires you to find a better way:

1. put the body in rest pose
2. apply the vertebras modifier (array+curve)
3. separate vertebras mesh into separate vertebras objects
4. then, create a vertex groups (1 vertex each) on the body back skin, one for each vertebra, which will get "attached" to that vertex later.
5. then I would create a "child of" constraint for each vertebra, with the right vertex group as "target"

eg: if this is your rigged body (here posed)

select the "body" and create (eg) two vertex group, one "skin" vertex each:

and

then "attach" each vertebra (here is a sphere) to its vertex group using the "child of" constraint (after adding the constraint, you may need to reposition the "vertebra" where it should be, if it goes elsewhere):

then, when you pose the rig, the body follows the rig, and the vertebras follow the body, without deforming.

here is my example .blend:

Note: parenting is not the same, will not work well, use this kind of constraint.

edit

after understanding better the rig/model pose, I expand to add details of what I intended...

preface:

• I reverted the rig to the "rest position"
• you created an "array" of 14 vertebras but not using the array modifier, instead you parented one base vertebra to a curve and used the "frame duplication" feature of such setup, setting the "path animation" frames of the curve to 14.

• since what I intended to do above needs 14 real vertebras, not duplicated ones, after setting the mesh "duplication" frames end also to 14 (it was 99, default probably), I used the "make duplicates real" comand, and removed the "base vertebra" parent to the curve.

and

obtaining 14 real vertebras, with no duplication

• then I've hidden all vertebras but the first 2, to keep the example simple to visualize (the whole model is really complex)

• after that, I went in edit mode of the body mesh, and created two separate vertex groups, 1 vertex each, each to be the "hook" for a single vertebra.

• then, I added to each vertebra the constraint "child of", targeted to each vertex group, and placed them where they should be in rest pose

in solid mode

from the side

• now, going back to posed mode, each vertebra sticks to and follows its vertex group, without deforming, but you may need to adjust something to make them move as you desire: the model spine moves quite a lot, and that move vertebreas also... maybe using vertex groups of more than 1 vertex blends the vertebra movement better ... I just tried to keep it simple.

here below you find the updated model with the 2 example vertebras seen in the screenshots above...