XrInstance

XrInstance is the top-level handle in the OpenXR API that represents a connection between an application and an OpenXR runtime. An application creates an XrInstance by calling xrCreateInstance and later destroys it with xrDestroyInstance. The instance owns runtime configuration, available extensions, and validation layers used during the lifetime of the application’s OpenXR usage. A single application may create multiple instances, though typically one per process.

Creation and configuration are performed by supplying an XrInstanceCreateInfo structure. This includes applicationInfo, which identifies the application (name, version) and the engine or middleware (name, version); enabledExtensionNames to opt into runtime extensions; and enabledApiLayerNames to request validation or other API layers. The runtime may refuse creation if required extensions or layers are unavailable, or if the system does not support OpenXR in the current context.

Instances expose runtime properties through calls such as xrGetInstanceProperties and xrEnumerateInstanceExtensionProperties. These allow an application to discover the runtime name and version, as well as the set of supported extensions. The instance is also used to obtain an XrSystemId for a given form factor via xrGetSystem, which is required to create sessions.

XrSession creation depends on the chosen system and is performed with xrCreateSession. An application may create and manage multiple sessions under a single XrInstance. The instance remains valid for the duration of the application’s OpenXR usage and is destroyed after all sessions are ended and the runtime is no longer needed.

Error handling during creation and usage covers common OpenXR error codes, such as initialization or availability failures.