A struct that holds a rich set of information that describes the bind pose of this Sprite.
Most importantly this struct describes the hierarchy and various other spatial relationships between the bones.
| length | The length of the bone. This is important for the leaf bones to describe their length without needing another bone as the terminal bone. |
| name | The name of the bone. This is useful when recreating bone hierarchy at editor or runtime. You can also use this as a way of resolving the bone path when a Sprite is bound to a more complex or richer hierarchy. |
| parentId | The ID of the parent of this bone. |
| position | The position in local space of this bone. |
| rotation | The rotation of this bone in local space. |