Using animated modifiers as a control rig

I’m trying to animate a book with turning pages. I have a rig that uses animated modifers to drive the page animations. As I am exporting to Unity, I need to convert that animation to a skeletal one. Can I use animated modifiers as a control rig for the bones and, if so, how do I do that?


No, not exactly. Depending on the modifier, you can have the bone adopt the positions/scales of vertices that are affected by the modifier, with scale to/ damped track/ locked track tracking particular vertex groups, perhaps of non-rendering meshes, but not all modifiers affect thing that way.

You could also code the modifiers into Unity. Depending on the modifier, some are quite simple.

Another option, but I’m not sure if Unity supports, is some kind of mesh cache, like an alembic; or shapekeys, which Unity definitely does support (but interpolation is probably going to be poor on shapekeys.)

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The animated modifiers in use are simple deform and bend. Would these be suitable for your first suggestion?

The page turn is driven by the following modifiers:

Simple Deform - Bend
Turns the page

Simple Deform - Twist
deforms the page so that the top right corner leads the page in the turn

deforms the page so that the page bows as it turns

I’m not a coder and I’m a Unity noob, so that is probably not a viable option in the short term.

Yes, I believe so, although they wouldn’t be at the same level of resolution as the modifier. I’m not very familiar with either of those modifiers, so I’m not totally certain. You would want the modifiers to use an empty for the transformation. After that, create a new object, with vertices at each bone’s +Y and +Z axis, mark them with vertex groups, apply the same modifiers on them; then set the bones to stretch to the +Y vertex (0.0 volume preservation) and locked track (lock Y, track Z) the +Z vertex. The more bones you have, the better the outcome.