Rewrite OpenXR hand tracking to reflect new architecture

Author: BastiaanOlij

tutorials/xr/img/openxr_enable_hand_tracking_meta.webp

@@ -31,6 +31,7 @@ Advanced topics
    xr_room_scale
    openxr_composition_layers
    openxr_hand_tracking
+   openxr_body_tracking
 
 Godot XR Tools
 --------------

tutorials/xr/img/openxr_hand_interaction_profile.webp

@@ -0,0 +1,38 @@
+.. _doc_openxr_body_tracking:
+
+OpenXR body tracking
+====================
+
+Support for full body tracking in OpenXR is only just becoming available for a select few platforms.
+As support solidifies information will be added to this page.
+
+HTC Tracker support
+-------------------
+
+An option that has been available for some time is doing full body tracking using HTC trackers.
+These are currently supported through SteamVR and on HTC Elite XR headsets.
+They are exposed through the action map system.
+
+These trackers are identified by their roles which are assigned to them when configured.
+Simply add :ref:`XRController3D <class_xrcontroller3d>` nodes as children to
+the :ref:`XROrigin3D <class_xrorigin3d>` node and assign one of the following trackers:
+
+.. list-table:: HTC trackers
+  :widths: 100
+  :header-rows: 0
+
+  * - /user/vive_tracker_htcx/role/handheld_object
+  * - /user/vive_tracker_htcx/role/left_foot
+  * - /user/vive_tracker_htcx/role/right_foot
+  * - /user/vive_tracker_htcx/role/left_shoulder
+  * - /user/vive_tracker_htcx/role/right_shoulder
+  * - /user/vive_tracker_htcx/role/left_elbow
+  * - /user/vive_tracker_htcx/role/right_elbow
+  * - /user/vive_tracker_htcx/role/left_knee
+  * - /user/vive_tracker_htcx/role/right_knee
+  * - /user/vive_tracker_htcx/role/waist
+  * - /user/vive_tracker_htcx/role/chest
+  * - /user/vive_tracker_htcx/role/camera
+  * - /user/vive_tracker_htcx/role/keyboard
+
+You can now use these as targets for IK modifiers on a full body avatar.