A node for inverse kinematics which may modify more than one bone. Base class of [SkeletonModifier3D]s that has some joint lists and applies inverse kinematics. This class has some structs, enums, and helper methods which are useful to solve inverse kinematics. [b]Note:[/b] The IK classes that extend this handle rotation only, with bone lengths cached. It means that a position movement between processed chains can cause unintended movement. Clears all settings. Returns the number of settings. Resets a state with respect to the current bone pose. Sets the number of settings.