Spine Rig setup SplineIK vs Bendy bones

I have been stuck on a spine rig for a while and having trouble to choose better setup for it. I am trying to create IK,FK and Spline IK spine setup. I have IK (chain A) and FK chain B which affects chain C (for switching). Chain C is controling deformation chain for the spine and this chain has splineIK setup on itself. I am facing trouble to rotate the splineIK chain with chain C as handles on spline IK are only translating the chain, not rotating it. In the end, I am looking for a setup which have IK FK switch chain setup and spline IK setup to improve the spine shape.
Any suggestions to improve this setup or how to rotate the spline chain using handles?
Thanks :slightly_smiling_face:

I would suggest using bbones for this task. Its easier to set up and faster as well. No need for a blend chain. If you’re familiar with Jason Schleifer’s IK/FK spine from his “Animation Friendly Rigging” course for Maya, you can apply this technique to a simple bbone setup.

FK_IK_spine.blend (635.7 KB)

This should get you started. Jason’s setup was much more sophisticated of course, but i think this is a good starting point.


Thanks for the reply. No, I haven’t scene it yet. I will check it out now. I have downloaded all the animator friendly rigging stuff and ready to learn :slight_smile:
Thanks you for the file too

Let me understand correctly: you have a spline IK chain, which is controlled by a curve, which is controlled by hook modifiers. When you rotate the objects controlling the hooks, the bones don’t rotate.

There are actually two problems here: hooks don’t affect curve tilt; curve tilt doesn’t affect spline IK anyway. That’s just the way Blender works right now (it’s a little disappointing.) Both of those are solvable, but it’s a pain in the butt. To acquire curve tilt from your hooks, you need to use drivers, but be careful about Euler issues. To acquire Y axis rotation on your spline IK, you need to duplicate the chain, parent duplicates to originals, then use locked track constraints-- and of course, you need something to locked track. The best thing is actually a curve deformed, non-rendering mesh, just an extruded string of verts to follow the curve, with vertex groups assigned for purposes of the locked track.

Or-- you could just acquire Y axis rotation for the whole chain from a parent bone and let it apply to the whole chain at once. It won’t distribute the twist, but it’s much much easier.


Thanks for the reply. I would try to implement that. Looks tedious but would be interesting to see the result. Actually I would like to have in the end is IK for translating chest, FK rotating spine and splineIK tweak the pose of the spine. In that way, animation graph will be clean and easy to fix ( also less control more functinality)

I found this old test from 2013. I remember giving up on that, not because it wouldnt work, but of the refresh issue when using more than one armature working one mesh. They fixed it in the meantime so this should work fine now.

splineIK_spine_test.blend (724.4 KB)

This method has some advantages over the bbone setup as you have control over each bone segment.

Thanks for the reply. For know, I am settling on IK chain and FK + SplineIk controls. I looks fuctionable and will improve it later.
Thanks for file. I will look into and try learn something more.

Thanks for the file. I checked it and it looks good. I will study it and hopefully, I will upload my result in a week. :slight_smile: