I’ve been testing spline IK for spine armature for a good while.
I’ve come to conclusion it isn’t very stable;
First of all, I don’t seem to be able to find built-in heading control. Either I can’t find it or there is no built in heading control for constrained armature bone chain.
Another thing probably resulting from this - when armature root bone which is parent of bones that control the spline (for example) is rotated 360 degrees along x-axis, vertically oriented spine deformation bones that are constrained to IK will flip halfway into full revolution. I don’t think I had any other controls as I was testing this with a blank scene.
Also, trying to fix heading and twist control with constraints like copy rotation doesn’t seem to help. I’ve tried several combinations to create center spine bones that take their heading from hip and chest bones… no success. Local + pose space seem to work the best, but bending spline sideways causes center bones to roll / change their heading for no obvious reason, even though hips and chest are facing forwards and even if the spine is otherwise pretty much vertical line along y-axis.
Is spline IK actually usable for spines in Blender?
I probably haven’t tried out all possible combinations of constraints, but not being able to do a 360 flip is really limiting… and not being able to control heading of IK bones renders it useless for me. Hope I’m wrong.