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 modes of operation.

Inheritance
object
SubsystemWithProvider
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>
XRSessionSubsystem
SimulationSessionSubsystem
Implements
Inherited Members
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>.OnCreate()
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>.OnStart()
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>.OnStop()
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>.OnDestroy()
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>.subsystemDescriptor
SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>.provider
SubsystemWithProvider.OnStart()
SubsystemWithProvider.OnStop()
SubsystemWithProvider.OnDestroy()
Namespace: UnityEngine.XR.ARSubsystems
Assembly: Unity.XR.ARSubsystems.dll
Syntax
public class XRSessionSubsystem : SubsystemWithProvider<XRSessionSubsystem, XRSessionSubsystemDescriptor, XRSessionSubsystem.Provider>, 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
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
int
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
bool
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
bool
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

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

requiresCommandBuffer

If the underlying subsystem provider requires access to the rendering pipeline then that provider will return true here.

Declaration
public bool requiresCommandBuffer { get; }
Property Value
Type Description
bool

true if the session provider overrides and handles OnCommandBufferSupportEnabled() and OnCommandBufferExecute(CommandBuffer) calls. Otherwise, false.

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

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
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 to 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 can have multiple, discrete modes of operation. A configuration represents the capabilities of a mode of operation, which can be a subset of the session's overal capabilities. That is, the session might 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 configurations. The caller owns the memory and is responsible for calling Dispose on 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 to 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()

OnCommandBufferExecute(CommandBuffer)

Invoked by the ARCommandBufferSupportRendererFeature.ExecuteRenderPass() method to provide subsystem access to the render pipeline's render pass command buffers.

Declaration
public void OnCommandBufferExecute(CommandBuffer commandBuffer)
Parameters
Type Name Description
CommandBuffer commandBuffer

The command buffer about to be executed.
See Also

OnCommandBufferSupportEnabled()

Invoked when using the Universal Rendering Pipeline in conjunction with the ARCommandBufferSupportRendererFeature to provide subsystem awareness that the render pipeline's render pass is enabled.

Declaration
public void OnCommandBufferSupportEnabled()
See Also

Reset()

Restarts a session. Stop and Start 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.

Implements