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    Interface IXRGrabTransformer

    An interface that allows the target position, rotation, and scale of an XRGrabInteractable to be calculated. The Process(XRGrabInteractable, UpdatePhase, ref Pose, ref Vector3) method is responsible for calculating the pose that the interactable will move to and the scale it will be resized to. Implementers are only responsible for calculating the pose and scale, which is handled and applied by Unity in XRGrabInteractable.

    Namespace: UnityEngine.XR.Interaction.Toolkit.Transformers
    Assembly: Unity.XR.Interaction.Toolkit.dll
    Syntax
    public interface IXRGrabTransformer
    Remarks

    Implementers are encouraged to derive from XRBaseGrabTransformer instead of this interface directly. However, advanced users can use this interface to totally override that behavior.

    Properties

    canProcess

    Whether this grab transformer can process targets. Transformers that can process targets receive calls to Process(XRGrabInteractable, UpdatePhase, ref Pose, ref Vector3), transformers that cannot process do not. Transformers will still have other event methods called to allow for initialization on the frame the grab changes happens.

    Declaration
    bool canProcess { get; }
    Property Value
    Type Description
    bool
    See Also
    XRBaseGrabTransformer
    XRGrabInteractable
    IXRDropTransformer

    Methods

    OnGrab(XRGrabInteractable)

    Called by Unity when the given Interactable is grabbed (in other words, when entering the Select state). This method won't be called again until the Interactable is released by every Interactor. Use this to do any code initialization based on the first Interactor that selects the Interactable.

    Declaration
    void OnGrab(XRGrabInteractable grabInteractable)
    Parameters
    Type Name Description
    XRGrabInteractable grabInteractable

    The XR Grab Interactable being grabbed.

    Remarks

    In other words, this will be called when the selection count changes from 0 to 1.

    See Also
    OnGrabCountChanged(XRGrabInteractable, Pose, Vector3)
    Grab()

    OnGrabCountChanged(XRGrabInteractable, Pose, Vector3)

    Called by Unity each time the number of selections changes for the given Interactable while grabbed by at least one Interactor, including when it is first grabbed. Use this to do any code initialization based on each Interactor currently selecting the Interactable, for example computing the initial distance between both Interactors grabbing the object.

    Declaration
    void OnGrabCountChanged(XRGrabInteractable grabInteractable, Pose targetPose, Vector3 localScale)
    Parameters
    Type Name Description
    XRGrabInteractable grabInteractable

    The XR Grab Interactable being grabbed.

    Pose targetPose

    The current target pose for the current frame.

    Vector3 localScale

    The current target scale of the Interactable's transform relative to the GameObject's parent.

    Remarks

    There will always be at least one Interactor selecting the Interactable when this method is called. In other words, this will be called when the selection count changes from 0 to 1 and whenever it subsequently changes while still above 0. This method is called by Unity right before Process(XRGrabInteractable, UpdatePhase, ref Pose, ref Vector3) if the selection count changed.

    Examples

    To get the number of Interactors selecting the Interactable in your implementation method:

    grabInteractable.interactorsSelecting.Count
    See Also
    XRBaseGrabTransformer
    XRGrabInteractable
    IXRDropTransformer

    OnLink(XRGrabInteractable)

    Called by Unity when the given Interactable links to this grab transformer. Use this to do any code initialization for the given Interactable.

    Declaration
    void OnLink(XRGrabInteractable grabInteractable)
    Parameters
    Type Name Description
    XRGrabInteractable grabInteractable

    The XR Grab Interactable being linked to this transformer.

    See Also
    OnUnlink(XRGrabInteractable)

    OnUnlink(XRGrabInteractable)

    Called by Unity when the given Interactable unlinks from this grab transformer. Use this to do any code cleanup for the given Interactable.

    Declaration
    void OnUnlink(XRGrabInteractable grabInteractable)
    Parameters
    Type Name Description
    XRGrabInteractable grabInteractable

    The XR Grab Interactable being unlinked from this transformer.

    See Also
    OnLink(XRGrabInteractable)

    Process(XRGrabInteractable, UpdatePhase, ref Pose, ref Vector3)

    Called by the linked Interactable to calculate the target pose and scale. Modify the value of targetPose and/or localScale (or neither).

    Declaration
    void Process(XRGrabInteractable grabInteractable, XRInteractionUpdateOrder.UpdatePhase updatePhase, ref Pose targetPose, ref Vector3 localScale)
    Parameters
    Type Name Description
    XRGrabInteractable grabInteractable

    The XR Grab Interactable to calculate the target pose and scale for.

    XRInteractionUpdateOrder.UpdatePhase updatePhase

    The update phase this is called during.

    Pose targetPose

    The target pose for the current frame.

    Vector3 localScale

    The target scale of the Interactable's transform relative to the GameObject's parent.

    Remarks

    When there is more than one linked grab transformer that can process, the updated value of each ref parameter is passed to each in series according to its order in the list. You can utilize this by, for example, having the first grab transformer compute the target pose, and the second compute just the scale.

    Examples

    If your transformer requires the use of two or more selections, you should first check for that condition in your implementation method:

    if (grabInteractable.interactorsSelecting.Count < 2) return;
    See Also
    ProcessInteractable(UpdatePhase)
    XRInteractionUpdateOrder.UpdatePhase

    See Also

    XRBaseGrabTransformer
    XRGrabInteractable
    IXRDropTransformer
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