XRBodyModifier3D — C# API

class XRBodyModifier3DReckfellSharpInherits SkeletonModifier3D

XRBodyModifier3D runs under Skeleton3D with XRBodyTracker data. Defaults are BodyTracker=/user/body_tracker, UpperBody/LowerBody/Hands enabled in BodyUpdate, and BoneUpdate=Full. A modifier connects no device and reconstructs no skeleton from a few trackers.

Bone names and hierarchy must match the data. Full applies relative positions and rotations; RotationOnly leaves most base positions but still updates Hips. MotionScale multiplies positions before relative conversion. BodyUpdate=0 does not disable every extra joint; Active=false disables processing completely.

Changing BodyTracker selects another source at the next processing step without remapping if Skeleton and BodyUpdate are unchanged. A missing tracker, HasTrackingData=false or invalid Root skips the update; the hand-style cached pose is not replayed here.

Skeleton3D applies modifiers temporarily and restores base pose. Read output inside ModificationProcessed. This executed example saves a diagnostic copy; LastModified can be stale when processing does not run:

C#
using Reckfell;

public partial class BonePoseProbe : Entity
{
    [Export] public Skeleton3D Skeleton { get; set; } = null!;
    [Export] public SkeletonModifier3D 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("BonePoseProbe: 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;
    }
}

Fourteen scenarios used a real Skeleton3D with synthetic data for all 87 joints. The diagnostic hierarchy has Spine under Hips and other nonroot bones under Root; it does not assess a real Humanoid rig. Partial-invalid-parent correctness, skin weights, deformation, animation blending, devices and rendered images were not tested. Consistent valid parent joints are required.

Reader and provider requirements: body tracking.

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

Constructors1

XRBodyModifier3DConstructor

# XRBodyModifier3D

C#
public XRBodyModifier3D();

Creates a modifier with BodyTracker=/user/body_tracker, all BodyUpdate regions and BoneUpdate=Full. Processing needs a Skeleton3D parent, matching bone names and an XRBodyTracker provider. Construction alone enables no tracking.

Properties3

BodyTrackerProperty

# BodyTracker

C#
public StringName BodyTracker { get; set; }

XRBodyTracker name, initially /user/body_tracker. The setter only stores the string: connects no provider and does not rebuild bone mapping. Changing the name selects another source for subsequent processing; bone mapping depends on Skeleton and BodyUpdate, not the tracker name.

BodyUpdateProperty

# BodyUpdate

C#
public XRBodyModifier3D.BodyUpdateEnum BodyUpdate { get; set; }

Mapping-region mask: UpperBody, LowerBody, Hands; all three by default. The setter rebuilds mapping when inside the tree. Filters primary-joint ranges; does not universally exclude Root and extra joints. Use inherited Active=false for complete disabling.

BoneUpdateProperty

# BoneUpdate

C#
public XRBodyModifier3D.BoneUpdateEnum BoneUpdate { get; set; }

Bone mode, initially Full. Full updates positions and rotations; RotationOnly updates rotations but still applies Hips position. Enum bounds are checked. Creates no skin weights and solves no calibration, scale or avatar placement.

Methods6

GetBodyTrackerStringName

# GetBodyTracker

C#
public StringName GetBodyTracker();

Configured tracker name, not proof of its presence or data.

Returns StringName

Provider name, initially /user/body_tracker.

GetBodyUpdateXRBodyModifier3D.BodyUpdateEnum

# GetBodyUpdate

C#
public XRBodyModifier3D.BodyUpdateEnum GetBodyUpdate();

Configured mapping-filter mask, not real-body capabilities.

Returns XRBodyModifier3D.BodyUpdateEnum

Configured modifier-region mask.

GetBoneUpdateXRBodyModifier3D.BoneUpdateEnum

# GetBoneUpdate

C#
public XRBodyModifier3D.BoneUpdateEnum GetBoneUpdate();

Configured Full/RotationOnly mode; RotationOnly retains the Hips-position exception.

Returns XRBodyModifier3D.BoneUpdateEnum

Configured bone mode, initially Full.

SetBodyTrackervoid

# SetBodyTracker

C#
public void SetBodyTracker(StringName trackerName);

Parameters
Name	Type	Default
`trackerName`	`StringName`	—

trackerName

Exact registered XRBodyTracker name. Changing it needs no remapping when Skeleton and BodyUpdate are unchanged.

SetBodyUpdatevoid

# SetBodyUpdate

C#
public void SetBodyUpdate(XRBodyModifier3D.BodyUpdateEnum bodyUpdate);

Parameters
Name	Type	Default
`bodyUpdate`	`XRBodyModifier3D.BodyUpdateEnum`	—

bodyUpdate

UpperBody/LowerBody/Hands mask; 0 is not a universal processing-disable command.

SetBoneUpdatevoid

# SetBoneUpdate

C#
public void SetBoneUpdate(XRBodyModifier3D.BoneUpdateEnum boneUpdate);

Parameters
Name	Type	Default
`boneUpdate`	`XRBodyModifier3D.BoneUpdateEnum`	—

boneUpdate

Full or RotationOnly; Max is the enum bound. Hips position updates in both modes.

XRBodyModifier3D.BodyUpdateEnum

Value	Description
`Hands = 4`	The skeleton's hand joints are updated.
`LowerBody = 2`	The skeleton's lower body joints are updated.
`UpperBody = 1`	The skeleton's upper body joints are updated.

XRBodyModifier3D.BoneUpdateEnum

Value	Description
`Full = 0`	The skeleton's bones are fully updated (both position and rotation) to match the tracked bones.
`Max = 2`	Represents the size of the `XRBodyModifier3D.BoneUpdateEnum` enum.
`RotationOnly = 1`	The skeleton's bones are only rotated to align with the tracked bones, preserving bone length.