Meta Body Tracking

Note

Check out the Meta Body Tracking Sample Project for a working demo of some Meta body tracking features.

The Godot OpenXR Vendors plugin supports a number of OpenXR extensions related to Meta body tracking. This document will walk through the provided features and how to use them.

Project Settings

To use body tracking, the Meta body tracking setting must be enabled in project settings. The extension setting can be found in Project Settings under the OpenXR section, the Body Tracking setting should be listed under Extensions in the Meta subcategory.

Body Tracking Setup

Body tracking features require a rigged mesh that can be retargeted to the Godot Humanoid layout. See the Godot documentation on Retargeting 3D Skeletons for more info.

../../_images/body_tracking_retarget.png — A skeleton being retargeted to the Godot Humanoid profile in the model's import settings

After you have a properly imported skeleton, you can apply body tracking to it with the XRBodyModifier3D node. Add this node as a child of the model's Skeleton3D.

../../_images/body_tracking_body_modifier_node_tree.png

The XRBodyModifier3D node's body_update property lets you indicate which areas of the skeleton you'd like to apply tracking data to: upper body, lower body, and hands. The bone_update property specifies how this data is applied: full (rotation and position), or rotation only.

Note

While hand tracking may be used as a part of body tracking, the hand tracking extension must be enabled to do this. See the documentation on Meta Hand Tracking for more info.

Lower Body Tracking

The basic Meta OpenXR body tracking extension XR_FB_body_tracking only provides data for upper body tracking. The extension XR_META_body_tracking_full_body, if supported, is what provides the lower body data. When supported by the runtime, this requires no further setup. You can check if XR_META_body_tracking_full_body is supported by calling is_full_body_tracking_supported().

Manual Height Override

When using body tracking, automatic calibration of a user's height will take place. Should you wish to override this, first check to see if the runtime supports the XR_META_body_tracking_calibration extension with is_body_tracking_height_override_supported(). If supported, you may suggest an override value within the range of 0.5 and 3.0 meters to suggest_body_tracking_height_override(). The runtime then may adjust the returned body tracking data to be scaled to this height.

Body Tracking Fidelity

The XR_META_body_tracking_fidelity extension allows users to request that body tracking data be collected with either a low or high level of fidelity. Check if this extension is supported with is_body_tracking_fidelity_supported(). If supported, you can request your desired fidelity level using request_body_tracking_fidelity(). By default, a high level of fidelity is used for body tracking, but low fidelity may be used to save CPU resources at the cost of lower body tracking precision.