Hi, again;
Welcome; So, I’ve entirely watched the Snail tutorial and I like it very much. That setup using Tangent, for the middle ‘control points’ in-between Bendy Bone Sets (I call a Bendy Bone Set each set composed of 1 Bendy Bone and 2 Controller Bones on each extremity), seems to be relatively reliable for some bending wavy organic Deformations for Facial Rig… Yes… I think this will be good enough; actually, I believe I’ll be able to make an experiment and if it works, later on I could create a complete Tutorial on this subject (Facial Rig with Bendy Bones Rig).
So, I’ve realized that the Snail tutorial uses the “middle control point” in a versatile way. If you know how to reproduce this Bendy Bone feature, then what you might have realized already (and that I’ve just realized by checking back on that other Bendy Bone Facial Rig tutorial I’ve sent), is that there are no “middle control points”, at least on most facial features including the Eyes. This means that if you keep reproducing that it won’t give you the exceptional “middle control points” that makes Posing the Facial Expressions a more intuitive process, and also you’ll get lesser Expressions on curvy shapes, as you be more limited on the bending possibilities.
This said, I think you are just giving too much attention to those optimization Addons (that unfortunately are failing more or less on our more recent Blender versions), and should focus on:
• Recreating the Snail “middle control point” on the Eye Top overall curve. This would give you for example, 2 Sets of Bendy Bones, with 3 control points (1 on the left, 1 on the top and 1 on the right). Then, you make this Snail tutorial approach to the Eye Bottom overall curve; this will give you, again 2 Sets of Bendy Bones. In the end, for a single Eye, you’ll get 4 Sets of Bendy Bones, except that 2 are for the Eye Top and the other 2 for the Eye Bottom; it is… plausible, yes, to make at least a continuous FK Chain for the Deform Bendy Bones, but not a cyclic Loop (since you cannot make a Cyclic Parenting in Blender), but this doesn’t mean the first Controller Bone for a ‘starting’ Bendy Bone Set cannot be reused as well as the last Controller Bone for a ‘last’ Bendy Bone Set —so like trying to make a cyclic loop around the Eye.
What you must make sure, is that the Controller Bones, all of them, gets firmly locked to some sort of ‘invisible curve surface object’, so then when you Pose them they will always be travelling on top of that surface Object; this can be achieved with a Shrinkwrap Bone Constraint on each of the Controller Bones. The invisible surface Object can be made as a (Add » Curve Object, to the Scene) NURBS Surface Curve Object, then you Edit it giving a proper shape, and then Mesh Menu » Convert » (Curve to) Mesh, than you Target the Bone Controllers’ Shrinkrwap Bone Constraints to that Mesh Object and then you just Hide it from Displaying on the 3D Viewport Editor.
With the Bendy Bones’ Controller Bones sliding onto that curve surface (somewhere slightly in front, further away from the curve surface of the real Eye of Susane the Monkey), this should offer a proper Location for the Controllers Bones so that they won’t disrupt the curve of the Bendy Bones on this Global Y Axis (forward/backward), and focus more on the XZ (left/right, top/down Transformation orientations for the Deform Bendy Bones).
The amount of Sets each Facial feature should have is a question to investigate. I don’t think really Expressive Eyebrow for example can ‘survive’ with just 1 Set; there would be need of at least 2 Sets, perhaps even 3 Sets. As in the Spline IK Rig that I know a bit more about (instead of “Bendy Bone Sets” there’s “Splines” as an equivalent group), the “size” or Length of the Bendy Bone on a Set is very important: some Sets might require to be very small in size, while others might require to be larger, because the start and ending of each Set (as with a Spline) indicate ‘middle control points’, which guarantie better Expressive, quality control on the curve.
I would like to have an example for Bendy Bone Sets (this is Facial Rig I’ve made using Spline IK Bone Constraint), on the Eyebrow, the Eyelid and the Eye Contour. Pay attention to the Posing of the Eyebrow:
I have 4 Controller Bones (indicating 4 legit Control Points [it’s a technical name for one element of Curve], for 3 Segments; so in total 3 Splines [‘sets of curves’], on the Curve Object there); the Spline to the WEST is very small (if that was a Bendy Bone Set, I believe it should be also a pretty small one, because the Curve shape there need to suffer a high angle change on a very small Segment)
I’m using Spline IK Rig as a reference not simply because it’s just what I’ve got presently, but mainly believe it’s pretty analogue to a Bendy Bones Rig problematic; I suspect it is plausible to obtain nice organic Deformations on Facial Rig using Bendy Bone Sets, but I wasn’t successful —I need to try it again, so thanks for bringing up the topic with new some references.
The kind of bendy Deformation that I’ve seen on the Snail tutorial, strongly suggests that with that Bendy Bone approach, for the creating of those ‘middle control points’, already lots of curvy Expressive potentials are available on a Bendy Bone for Facial Rig; it might actually be much easier than I was thinking originally.
