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Dynamic sliding controls approach for EPIC rigs

Rigging General
#1

Hi guys,

I’m trying to think of a way to rig this type of character on which the eyes
are a solid shape with controls that stick to a surface.

The ideal behavior as I imagine it would be having a ghost slider root and
sub-controls for shape deformations which follow the root but also slide

Screenshot_1
Screenshot_1786×771 156 KB

The problem is that the underlying surface is also going to deform, and
I’d like these controls to conform to the deformation of that mesh.

On top of that, this is meant to be a game character for UE so I’m using
EPIC components, but I’m happy to look into custom components if the
goal requires it

It’s been a while since I got to experiment with rigging because I’m a
generalist and I’m having trouble coming up with a strategy on the spot,
so any pointers or ideas on how to do this would be greatly helpful

#2

Shifter components don’t really have that kind of goal, to give these kinds of complex deformations. They are more mechanical, like limbs/chains/spines, etc. Custom components isn’t likely what you are looking for, probably.

There are a couple things I could think of, and you’d have to combine them in clever ways:

  • If the base sphere is a perfect sphere, you can rotate as a first stage, and you will perfectly follow the sphere’s surface. Look at how the eye rigger works. It has a curve which aims, but the aim causes a rotation around a single point, for a sphere effect.
  • Instead of driving the geometry, for UE, you might need to drive joints along the sphere, and skin the elements.
  • To deform along with the sphere, you could pin the joints to some nurbs surface or sphere (uvPin or something), and then deform that sphere identically along with your polygon sphere. (You could pin directly to the polygons, but that will hurt if you need to update the model. Avoid if possible.) You will have to bake the joints at the end, before exporting to UE.
  • Whether you use uvPin or something else, don’t use heavy surfaceAttach nodes. Don’t use poly rivets. Your rig will be very slow. closestPointOnSurface might be ok.
  • You could look into Ozone Kite (or Kite Ozone?) to get wild special deformations like this. It will be a learning curve, but it seems extremely parametric and powerful.
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