XR: Expose the OpenXR user paths in the event data for XR events

The use-case is to allow an event handler (in C or a plugin) to
distinguish which hand produced the XR event.

The alternative is to register separate actions for each hand (e.g.
"trigger_left" and "trigger_right"), and duplicate the device bindings
(Oculus, HTC Vive, etc) for each action. Other than the problem of code
duplication, this isn't conceptually efficient since "trigger_left" and
"trigger_right" both represent the same event "trigger", and the
identity of the hand that produced that event is just a property of
that event.

Adds two string fields to the XrEventData called user_path and
user_path_other. The user_path_other field will be populated if the
event is a bimanual one (i.e. two-handed). This follows the pattern
used by the rest of the XrEventData struct for bimanual events (e.g.
state, state_other).

Reviewed By: muxed-reality

1 files changed, 4 insertions, 0 deletions

diff --git a/source/blender/windowmanager/WM_types.h b/source/blender/windowmanager/WM_types.h
index 3ee5c85c031..9e9f195c430 100644
--- a/source/blender/windowmanager/WM_types.h
+++ b/source/blender/windowmanager/WM_types.h
@@ -812,6 +812,10 @@ typedef struct wmXrActionData {
   char action_set[64];
   /** Action name. */
   char action[64];
+  /** User path. E.g. "/user/hand/left" */
+  char user_path[64];
+  /** Other user path, for bimanual actions. E.g. "/user/hand/right" */
+  char user_path_other[64];
   /** Type. */
   eXrActionType type;
   /** State. Set appropriately based on type. */