The parent of a hierarchy of [Bone2D]s, used to create a 2D skeletal animation. [Skeleton2D] parents a hierarchy of [Bone2D] nodes. It holds a reference to each [Bone2D]'s rest pose and acts as a single point of access to its bones. To set up different types of inverse kinematics for the given Skeleton2D, a [SkeletonModificationStack2D] should be created. The inverse kinematics be applied by increasing [member SkeletonModificationStack2D.modification_count] and creating the desired number of modifications. $DOCS_URL/tutorials/animation/2d_skeletons.html Executes all the modifications on the [SkeletonModificationStack2D], if the Skeleton2D has one assigned. Returns a [Bone2D] from the node hierarchy parented by Skeleton2D. The object to return is identified by the parameter [param idx]. Bones are indexed by descending the node hierarchy from top to bottom, adding the children of each branch before moving to the next sibling. Returns the number of [Bone2D] nodes in the node hierarchy parented by Skeleton2D. Returns the local pose override transform for [param bone_idx]. Returns the [SkeletonModificationStack2D] attached to this skeleton, if one exists. Returns the [RID] of a Skeleton2D instance. Sets the local pose transform, [param override_pose], for the bone at [param bone_idx]. [param strength] is the interpolation strength that will be used when applying the pose, and [param persistent] determines if the applied pose will remain. [b]Note:[/b] The pose transform needs to be a local transform relative to the [Bone2D] node at [param bone_idx]! Sets the [SkeletonModificationStack2D] attached to this skeleton. Emitted when the [Bone2D] setup attached to this skeletons changes. This is primarily used internally within the skeleton.