XRHandModifier3D

XRHandModifier3D runs under Skeleton3D. It matches Left/Right-prefixed Humanoid bones according to tracker hand, such as LeftHand and LeftIndexProximal. Names and hierarchy must match before assessing deformation of a real model.

Full changes positions and rotations; RotationOnly changes rotations. Transforms are relative to parent joints and positions receive skeleton MotionScale. After a valid update, HasTrackingData=false reapplies cached pose. An invalid Palm with HasTrackingData=true instead skips modification; these are different cases.

Modifier output is temporary: read poses inside ModificationProcessed before Skeleton3D restores its base pose. This example stores a copy; LastModified can become stale when the modifier is disabled or the source disappears:

using Reckfell;

public partial class HandPoseProbe : Entity
{
    [Export] public Skeleton3D Skeleton { get; set; } = null!;
    [Export] public XRHandModifier3D Modifier { get; set; } = null!;
    [Export] public int Bone { get; set; }
    public Transform3D LastModified { get; private set; } = Transform3D.Identity;

    public override void _Ready()
    {
        if (Skeleton is null || Modifier is null || Modifier.GetSkeleton() != Skeleton
            || Bone < 0 || Bone >= Skeleton.GetBoneCount())
        {
            ReckfellApi.PushError("HandPoseProbe: assign a matching skeleton, modifier and bone index.");
            return;
        }
        Modifier.ModificationProcessed += Capture;
    }
    private void Capture() => LastModified = Skeleton.GetBonePose(Bone);
    public override void _ExitTree()
    {
        if (Modifier is not null && ReckfellObject.IsInstanceValid(Modifier))
            Modifier.ModificationProcessed -= Capture;
    }
}

Important source limitation: the ORIENTATION_VALID scan does not become a per-child validity guard before application. Partially invalid child data was not accepted by this test; used joints and parents need a consistent valid set. Active=false disables processing. Do not hide invalidity by manually substituting flags on a real provider.

Fourteen checks used a real Skeleton3D, all 26 matched bones and synthetic joints. Modes, cache, MotionScale, tracker changes and the exact HandPoseProbe were exercised. Real hands, skin weights, deformation, animation blending and image quality were not checked. Setup and pinch: hand tracking.

Declarations checked against C# SDK 1.0.0. Expand a name to see declarations and documentation.

public XRHandModifier3D();

public XRHandModifier3D.BoneUpdateEnum BoneUpdate { get; set; }

public StringName HandTracker { get; set; }

public XRHandModifier3D.BoneUpdateEnum GetBoneUpdate();

public StringName GetHandTracker();

public void SetBoneUpdate(XRHandModifier3D.BoneUpdateEnum boneUpdate);

public void SetHandTracker(StringName trackerName);