Class XRHandSkeletonDriver

Controls a hierarchy of Transforms driven by joints in an XRHand. This component subscribes to events from an XRHandTrackingEvents component to move and rotate the joints when the hand is updated.

Inheritance
object
Object
Component
Behaviour
MonoBehaviour
XRHandSkeletonDriver
Implements
Inherited Members
Object.FindObjectsByType<T>(FindObjectsSortMode)
Object.FindObjectsByType<T>(FindObjectsInactive, FindObjectsSortMode)
Object.FindFirstObjectByType<T>()
Object.FindAnyObjectByType<T>()
Object.FindFirstObjectByType<T>(FindObjectsInactive)
Object.FindAnyObjectByType<T>(FindObjectsInactive)
Namespace: UnityEngine.XR.Hands
Assembly: Unity.XR.Hands.dll
Syntax
[HelpURL("https://docs.unity3d.com/Packages/com.unity.xr.hands@1.4/api/UnityEngine.XR.Hands.XRHandSkeletonDriver.html")]
public class XRHandSkeletonDriver : MonoBehaviour, ISerializationCallbackReceiver

Fields

m_HasJointTransformMask

An array of booleans tracking which joint indexes have a valid transform to drive. This is calculated once when the references change to avoid a null check every time the joint is updated.

Declaration
protected bool[] m_HasJointTransformMask
Field Value
Type Description
bool[]

m_HasRootTransform

A boolean tracking whether the root transform is valid. This is calculated once when the root transform changes to avoid a null check every time the root is updated.

Declaration
protected bool m_HasRootTransform
Field Value
Type Description
bool

m_JointLocalPoses

The array of joint local poses indexed by the XRHandJointID which is updated by the method UpdateJointLocalPoses(XRHandJointsUpdatedEventArgs) and then applied to the joint transforms by the method ApplyUpdatedTransformPoses().

Declaration
protected NativeArray<Pose> m_JointLocalPoses
Field Value
Type Description
NativeArray<Pose>

m_JointTransformReferences

The list of joint to transform references

Declaration
[SerializeField]
[Tooltip("List of XR Hand Joints with a reference to a transform to drive.")]
protected List<JointToTransformReference> m_JointTransformReferences
Field Value
Type Description
List<JointToTransformReference>

m_JointTransforms

The array of joint data indexed by the XRHandJointID which is accessible via ToIndex(XRHandJointID).

Declaration
protected Transform[] m_JointTransforms
Field Value
Type Description
Transform[]

Properties

handTrackingEvents

The XRHandTrackingEvents component that will be the source of hand tracking events for this driver.

Declaration
public XRHandTrackingEvents handTrackingEvents { get; set; }
Property Value
Type Description
XRHandTrackingEvents

hasRootOffset

Bool tracking whether the root requires an offset to be applied to it.

Declaration
protected virtual bool hasRootOffset { get; }
Property Value
Type Description
bool

jointTransformReferences

The serialized list of XRHandJointID with a reference to a transform to drive. After this list is finished being assigned or modified, use the method InitializeFromSerializedReferences() to update the runtime mapping of transforms to drive.

Declaration
public List<JointToTransformReference> jointTransformReferences { get; set; }
Property Value
Type Description
List<JointToTransformReference>

rootOffset

Offset translation applied to hand root position.

Declaration
protected virtual Vector3 rootOffset { get; }
Property Value
Type Description
Vector3

rootTransform

The Transform that will be driven by the hand's root position and rotation.

Declaration
public Transform rootTransform { get; set; }
Property Value
Type Description
Transform

Methods

ApplyRootPoseOffset(Vector3)

Applies an offset to the root pose of the hand skeleton. This can be used to adjust the position of the hand in situations where you want the hand visual to stop moving when interacting with an object. The offset is applied in the local space of the hand's root transform.

Declaration
public void ApplyRootPoseOffset(Vector3 rootPoseOffset)
Parameters
Type Name Description
Vector3 rootPoseOffset

A Vector3 representing the offset to apply to the root pose of the hand skeleton.

ApplyUpdatedTransformPoses()

Applies the values in the m_JointLocalPoses array to the m_JointTransforms array.

Declaration
protected virtual void ApplyUpdatedTransformPoses()
Remarks

Override this method to change how the local hand joint poses affect the transforms, such as ignoring position, or converting to a different coordinate space.

FindJointsFromRoot(List<string>)

Finds the joint transform references from the root.

Declaration
public virtual void FindJointsFromRoot(List<string> missingJointNames)
Parameters
Type Name Description
List<string> missingJointNames

A list of strings to list the joints that were not found.
Remarks

Override this method to change how the joint transform references are found from the root and setup in the m_JointTransformReferences. This method is called from the default inspector editor UI when the Find Joints button is clicked.

InitializeFromSerializedReferences()

Converts the serialized list jointTransformReferences to a mapping of Transforms to drive. This method is called automatically via OnAfterDeserialize. It can be called manually after the list of Transform references is modified at runtime to apply the changes.

Declaration
public void InitializeFromSerializedReferences()

OnDisable()

See MonoBehaviour. MonoBehaviour OnDisable method that unsubscribes from hand tracking events and disposes the joint local poses array.

Declaration
protected virtual void OnDisable()

OnEnable()

See MonoBehaviour. MonoBehaviour OnEnable method that subscribes to hand tracking events and allocates the joint local poses array.

Declaration
protected virtual void OnEnable()

OnJointsUpdated(XRHandJointsUpdatedEventArgs)

Updates all the joints of the hand. This method calls UpdateJointLocalPoses(XRHandJointsUpdatedEventArgs) to calculate the local poses of the joints and then immediately calls ApplyUpdatedTransformPoses() to apply the changes to the joint Transforms.

Declaration
protected virtual void OnJointsUpdated(XRHandJointsUpdatedEventArgs args)
Parameters
Type Name Description
XRHandJointsUpdatedEventArgs args

The event arguments for the XRHand joints updated.
Remarks

Override this method to change either how or when the m_JointLocalPoses array is updated and applied to the transforms.

OnRootPoseUpdated(Pose)

Update the rootTransform's local position and rotation with the hand's root pose.

Declaration
protected virtual void OnRootPoseUpdated(Pose rootPose)
Parameters
Type Name Description
Pose rootPose

The root pose of the hand.
Remarks

Override this method to change how to the root pose is applied to the skeleton.

Reset()

See MonoBehaviour.

Declaration
protected virtual void Reset()

ResetRootPoseOffset()

Resets the offset of the root pose of the hand skeleton back to zero. This can be used to remove any previously applied offset, restoring the hand's root pose to its original position.

Declaration
public void ResetRootPoseOffset()

UpdateJointLocalPoses(XRHandJointsUpdatedEventArgs)

Calculates the local poses for all the joints in the hand using the standard parent hierarchy. Call this method to update the m_JointLocalPoses array with the latest joint data.

Declaration
protected void UpdateJointLocalPoses(XRHandJointsUpdatedEventArgs args)
Parameters
Type Name Description
XRHandJointsUpdatedEventArgs args

The event arguments for the XRHand joints updated.

Implements