Architecture

Unity OpenXR: Spatial Entities functions as both an OpenXR Feature Group and an AR Foundation provider plug-in.

About OpenXR

OpenXR is an open-source standard that defines an interface between XR apps and platform runtimes. The OpenXR specification contains two categories of features:

• Core features: present on every platform
• Extensions: optional and might not be implemented by some platforms.

Unity's OpenXR Plug-in integrates core features, while this package integrates the OpenXR Spatial Entities Extensions (Khronos Blog) using Unity's OpenXR native API.

OpenXR extensions

The OpenXR Spatial Entities Extensions can be found in the Khronos Group OpenXR Specification.

This package enables support for the following OpenXR extensions in your project:

Extension	Usage	Description
XR_ANDROID_spatial_component_subsumed_by	Planes	Enables apps to detect when the runtime subsumes one tracked plane into another because both planes represent the same real-world surface.
XR_ANDROID_spatial_discovery_raycast	Ray casts	Enables apps to cast rays against spatial entities, and adds a capability for casting against the environment depth buffer.
XR_ANDROID_spatial_entity_bound_anchor	Anchors	Enables apps to attach an anchor to a spatial entity, such as a plane, so the anchor maintains its pose relative to that entity.
XR_EXT_future	Anchors, Markers, Planes, Ray casts	This extension provides a general-purpose framework for asynchronous API design, and is a dependency of all spatial entities extensions.
XR_EXT_spatial_anchor	Anchors	Enables apps to create anchors.
XR_EXT_spatial_entity	Anchors, Markers, Planes, Ray casts	This extension defines the core concepts and foundations for spatial entities, and is a dependency of all other spatial entities extensions.
XR_EXT_spatial_marker_tracking	Markers	Enables apps to detect and track markers.
XR_EXT_spatial_persistence	Anchors	Enables apps to discover persistent spatial entities across multiple OpenXR sessions.
XR_EXT_spatial_persistence_operations	Anchors	Enables apps to persist and unpersist spatial entities.
XR_EXT_spatial_plane_tracking	Planes	Enables apps to track planar surfaces in the environment.

Note

Unity officially supports this package for use with the Meta Horizon OS and Android XR runtimes, but other OpenXR runtimes may also implement the required extensions. Refer to the OpenXR Runtime Extension Support Report for a self-reported list of OpenXR runtimes that support the required extensions.