Skeleton Compatibility

Overview

Skeleton Compatibility feature allows the animation created based on skeleton A to be played on compatible skeletons (compatible skeleton hierarchies) at runtime (doesn't need to be generated offline), so that the animation can be shared among multiple compatible skeletons.

Prerequisites

Certain conditions need to be met for skeletons to be compatible. Skeletons that are compatible with each other need to be consistent in their skeleton hierarchies and bone naming.

Skeleton A and skeleton B share the same skeleton hierarchies and bone naming, and skeleton B has additions or deletions only at the end of the bone chains compared to skeleton A. In this case, skeleton B can be considered as a compatible skeleton of skeleton A, and animations made based on skeleton A can be played on skeleton B. Make sure you don't break from the middle of one of the bone chains of skeleton A and insert a new bone. If this happens, then it will be considered incompatible.

For example, if you add a bone chain to a character's head bone to drive a ponytail, or add a bone chain to a character's skeleton to drive a tail, then the new skeleton is compatible with the original one.

Examples:

If you add bone 4 to the end of the bone chain (composed of bone 1, bone 2 and bone 3) of the original skeleton, then the new skeleton is compatible with the original one.

If you add bone 4 in the middle of the bone chain of the original skeleton (composed of bone 1, bone 2 and bone 3) without breaking the original skeleton hierarchy, then the new skeleton is compatible with the original one.

If you break the bone chain of the original skeleton (composed of bone 1, bone 2 and bone 3) in the middle and insert bone 4, then the original skeleton hierarchy is altered, and the new skeleton is not compatible with the original one.

Reusing Animations

The skeleton hierarchies and bone naming of the main skeletons of Actor SK_Human and Actor Human_Hair are consistent, and compared to the main skeleton of SK_Human, that of Human_Hair has an extra ponytail bone chain at its head bone. The two skeletons are compatible with each other, and Human_Hair can reuse the animation of SK_Human.

SK_Human Actor

Human_Hair Actor

SK_Human Skeleton

Human_Hair Skeleton

Double-click the Human_Hair Actor to open the Actor Editor.

Drag the default_run animation of the SK_Human asset into the Action List of Human_Hair in the Actor Editor, and the Human_Hair Actor can play the default_run animation normally.

Final Result

The Human_Hair asset reuses the default_run animation of the SK_Human asset.