Class XRSessionSubsystem

This subsystem controls the lifecycle of an XR session. Some platforms, particularly those that have non-XR modes, need to be able to turn the session on and off to enter and exit XR mode(s) of operation.

Inheritance
Object
Subsystem
Subsystem<XRSessionSubsystemDescriptor>
XRSubsystem<XRSessionSubsystemDescriptor>
XRSessionSubsystem
XRSessionSubsystemImpl
Inherited Members
Namespace: UnityEngine.XR.ARSubsystems
Syntax
public abstract class XRSessionSubsystem : XRSubsystem<XRSessionSubsystemDescriptor>, ISubsystem

Constructors

XRSessionSubsystem()

Do not call this directly. Call create on a valid XRSessionSubsystemDescriptor instead.

Declaration
public XRSessionSubsystem()

Properties

configurationChooser

Get or set the ConfigurationChooser used by DetermineConfiguration(Feature). If set to null, the DefaultConfigurationChooser is used.

Declaration
public ConfigurationChooser configurationChooser { get; set; }
Property Value
Type Description
ConfigurationChooser

currentConfiguration

The current Configuration in use by the session.

Declaration
public Configuration? currentConfiguration { get; }
Property Value
Type Description
Nullable<Configuration>
See Also

currentTrackingMode

Get the current tracking mode in use by the subsystem.

Declaration
public Feature currentTrackingMode { get; }
Property Value
Type Description
Feature

frameRate

The native update rate of the AR Session.

Declaration
public int frameRate { get; }
Property Value
Type Description
Int32
Exceptions
Type Condition
NotSupportedException

Thrown if supportsMatchFrameRate is False.

matchFrameRateEnabled

Whether the AR session update is synchronized with the Unity frame rate. If true, Update(XRSessionUpdateParams) should block until the next AR frame is available.

Declaration
public bool matchFrameRateEnabled { get; }
Property Value
Type Description
Boolean
Exceptions
Type Condition
NotSupportedException

Thrown if supportsMatchFrameRate is False.

matchFrameRateRequested

Get or set whether the match frame rate feature should be enabled. When enabled, the AR session update is synchronized with the Unity frame rate.

Declaration
public bool matchFrameRateRequested { get; set; }
Property Value
Type Description
Boolean
See Also

nativePtr

Returns an implementation-defined pointer associated with the session.

Declaration
public IntPtr nativePtr { get; }
Property Value
Type Description
IntPtr

notTrackingReason

Gets the NotTrackingReason for the session.

Declaration
public NotTrackingReason notTrackingReason { get; }
Property Value
Type Description
NotTrackingReason

provider

The provider created by the implementation that contains the required session functionality.

Declaration
protected XRSessionSubsystem.Provider provider { get; }
Property Value
Type Description
XRSessionSubsystem.Provider

requestedFeatures

Get the requested Features. These are used to determine the session's Configuration.

Declaration
public Feature requestedFeatures { get; }
Property Value
Type Description
Feature
See Also

requestedTrackingMode

The requested tracking mode. Query for support with SubsystemDescriptor.supportedTrackingModes.

Declaration
public Feature requestedTrackingMode { get; set; }
Property Value
Type Description
Feature

sessionId

Returns a unique session identifier for this session.

Declaration
public Guid sessionId { get; }
Property Value
Type Description
Guid

trackingState

Gets the TrackingState for the session.

Declaration
public TrackingState trackingState { get; }
Property Value
Type Description
TrackingState

Methods

CreateProvider()

Implement this to provide this class with an interface to platform specific implementations.

Declaration
protected abstract XRSessionSubsystem.Provider CreateProvider()
Returns
Type Description
XRSessionSubsystem.Provider

An implementation specific provider.

DetermineConfiguration(Feature)

Determines the Configuration the session will use given the requested features.

Declaration
public Configuration? DetermineConfiguration(Feature features)
Parameters
Type Name Description
Feature features

A set of requested Features.
Returns
Type Description
Nullable<Configuration>

The Configuration the session would use given the requested features, or null if configuration introspection is not available.
Remarks

This method uses the current configurationChooser to choose a configuration using the requested features and the capabilities of the available configurations. The configuration chooser is customizable, see ConfigurationChooser. If you do not set a configuration chooser, the DefaultConfigurationChooser is used.

You can use this method to determine what would happen if you were to enable or disable a particular feature. For example, you can use this method to determine which features would be enabled if you were to change the camera mode from WorldFacingCamera to UserFacingCamera.

See Also

GetAvailabilityAsync()

Asynchronously retrieves the SessionAvailability. Used to determine whether the current device supports XR and if the necessary software is installed.

Declaration
public Promise<SessionAvailability> GetAvailabilityAsync()
Returns
Type Description
Promise<SessionAvailability>

A Promise<T> which can be used to determine when the availability has been determined and retrieve the result.
Remarks

This platform-agnostic method is typically implemented by a platform-specific package.

GetConfigurationDescriptors(Allocator)

Get the list of supported configuration descriptors. The session may have multiple, discrete "modes" of operation. A configuration represents the capabilities of a "mode" of operation, which may be a subset of the session's overal capabilities. That is, the session may support many features, but not all at the same time. This is used by DetermineConfiguration(Feature) to determine the best configuration given a set of requested features.

Declaration
public NativeArray<ConfigurationDescriptor> GetConfigurationDescriptors(Allocator allocator)
Parameters
Type Name Description
Allocator allocator

The allocator to use for the returned NativeArray.
Returns
Type Description
NativeArray<ConfigurationDescriptor>

Allocates a new NativeArray and populates it with descriptors describing the supported configuration(s). The caller owns the memory and is responsible for Dispose'ing of the NativeArray.

InstallAsync()

Asynchronously attempts to install XR software on the current device. Throws if supportsInstall is false.

Declaration
public Promise<SessionInstallationStatus> InstallAsync()
Returns
Type Description
Promise<SessionInstallationStatus>

A Promise<T> which can be used to determine when the installation completes and retrieve the result.
Remarks

This platform-agnostic method is typically implemented by a platform-specific package.

OnApplicationPause()

Should be invoked when the application is paused.

Declaration
public void OnApplicationPause()

OnApplicationResume()

Should be invoked when the application is resumed.

Declaration
public void OnApplicationResume()

OnDestroyed()

Destroys the session.

Declaration
protected sealed override void OnDestroyed()
Overrides
UnityEngine.XR.ARSubsystems.XRSubsystem<UnityEngine.XR.ARSubsystems.XRSessionSubsystemDescriptor>.OnDestroyed()

OnStart()

Starts or resumes the session.

Declaration
protected sealed override void OnStart()
Overrides
UnityEngine.XR.ARSubsystems.XRSubsystem<UnityEngine.XR.ARSubsystems.XRSessionSubsystemDescriptor>.OnStart()

OnStop()

Pauses the session.

Declaration
protected sealed override void OnStop()
Overrides
UnityEngine.XR.ARSubsystems.XRSubsystem<UnityEngine.XR.ARSubsystems.XRSessionSubsystemDescriptor>.OnStop()

Reset()

Restarts a session. OnStop() and OnStart() pause and resume a session, respectively. Restart resets the session state and clears and any detected trackables.

Declaration
public void Reset()

Update(XRSessionUpdateParams)

Trigger the session's update loop.

Declaration
public void Update(XRSessionUpdateParams updateParams)
Parameters
Type Name Description
XRSessionUpdateParams updateParams

Data needed by the session to perform its update.