Constant ovr_sys::ovrTrackingOrigin_EyeLevel

pub const ovrTrackingOrigin_EyeLevel: ovrTrackingOrigin = 0;

Tracking system origin reported at eye (HMD) height

Prefer using this origin when your application requires matching user’s current physical head pose to a virtual head pose without any regards to a the height of the floor. Cockpit-based, or 3rd-person experiences are ideal candidates. When used, all poses in ovrTrackingState are reported as an offset transform from the profile calibrated or recentered HMD pose. It is recommended that apps using this origin type call ovr_RecenterTrackingOrigin prior to starting the VR experience, but notify the user before doing so to make sure the user is in a comfortable pose, facing a comfortable direction.