An XR runtime is a software package which provides XR applications with access to XR platforms and devices. It can also implement functionality. Examples include the Oculus runtime and the SteamVR runtime. An XR runtimes can provide XR applications with a variety of interfaces with which to interact with them, which might conform to a standard such as OpenXR or OpenVR.

OpenXR is an open, royalty-free standard for APIs that provide XR applications with access to XR platforms and devices. This is implemented in the XR runtime software supplied by the manufacturer of XR hardware. Application support for OpenXR is potentially useful for preservation purposes — as it is a open standard, which will make keeping software available that

OpenXR is developed by a working group managed by the Khronos Group consortium, who describe it as follows:

OpenXR is an API (Application Programming Interface) for XR applications. XR refers to a continuum of real-and-virtual combined environments generated by computers through human-machine interaction and is inclusive of the technologies associated with virtual reality (VR), augmented reality (AR) and mixed reality (MR). OpenXR is the interface between an application and an in-process or out-of-process "XR runtime system", or just "runtime" hereafter. The runtime may handle such functionality as frame composition, peripheral management, and raw tracking information.

Optionally, a runtime may support device layer plugins which allow access to a variety of hardware across a commonly defined interface.

— https://www.khronos.org/registry/OpenXR/specs/1.0/html/xrspec.html

Up until the arrival of OpenXR, support for each manufacturers API would have to be built into the XR applications if they were to be used.OpenXR attempts to solve the problem of compatibility between XR applications and XR hardware. Image source: https://www.khronos.org/openxr/.

Using OpenXR

In order to make use of OpenXR, you need to:

1. Develop software which supports — see Engine Implementations below.

2. Make use of an XR platform which supports it — see XR Runtime Implementations below.

XR Runtime Implementations

OpenXR is steadily being adopted by XR platforms, as they build support into their XR runtime software. The table below lists the XR runtimes which currently support OpenXR.

Engine Implementations