XR session interface. More...

#include <XRSession.h>

Inheritance diagram for LLGL::XRSession:

Public Member Functions
	~XRSession ()
	Releases internal data. The owning XRSystem releases native XR resources.
virtual XRSessionState	GetState () const =0
	Returns the current runtime-reported session state.
virtual XREnvironmentBlendMode	GetEnvironmentBlendMode () const =0
	Returns the environment blend mode the runtime selected for this session.
virtual ArrayView< Format >	GetSupportedColorFormats () const =0
	Returns the list of color formats supported by this session for swap-chains, in runtime-preferred order.
virtual ArrayView< Format >	GetSupportedDepthFormats () const =0
	Returns the list of depth-stencil formats supported by this session for swap-chains, in runtime-preferred order.
virtual XRSwapChain *	CreateSwapChain (const XRSwapChainDescriptor &swapChainDesc)=0
	Creates a new XR swap-chain.
virtual void	Release (XRSwapChain &swapChain)=0
	Releases the specified swap-chain. After this call, the specified object must no longer be used.
virtual bool	IsRunning () const =0
	Returns true if the session has been signalled ready by the runtime and BeginFrame may be invoked.
virtual bool	WaitFrame (XRFrameState &frameState)=0
	Waits for the previous frame to finish and retrieves the next frame state. Must be called before BeginFrame at the beginning of the app's update.
virtual bool	BeginFrame ()=0
	Begins a new XR frame. Must be called after WaitFrame().
virtual bool	EndFrame (float nearZ, float farZ, ArrayView< XRSwapChain * > swapChains)=0
	Submits a frame to the runtime.
virtual bool	GetViewState (DynamicVector< XRViewPose > &viewsOut)=0
	Sample and return the latest predicted poses for the session's views.
virtual bool	GetNativeHandle (void *nativeHandle, std::size_t nativeHandleSize)=0
	Returns the native handle of this XR Session.
virtual const Report *	GetReport () const =0
	Returns a pointer to the report or null if there is none.
Public Member Functions inherited from LLGL::Interface
virtual bool	IsInstanceOf (int id) const
	Returns true if this object is an instance of the specified interface.
Public Member Functions inherited from LLGL::NonCopyable
	NonCopyable (const NonCopyable &)=delete
NonCopyable &	operator= (const NonCopyable &)=delete
virtual	~NonCopyable ()=default

Protected Member Functions
	XRSession ()
	Allocates the internal data.
Protected Member Functions inherited from LLGL::NonCopyable
	NonCopyable ()=default

Detailed Description

XR session interface.

Remarks: Drives the per-frame loop: BeginFrame yields predicted view poses, the application renders into one swap-chain image per view, and EndFrame submits the projection layer back to the runtime.

See also: XRSystem::CreateSession

Constructor & Destructor Documentation

◆ ~XRSession()

LLGL::XRSession::~XRSession ( )

Releases internal data. The owning XRSystem releases native XR resources.

◆ XRSession()

LLGL::XRSession::XRSession ( )

protected

Allocates the internal data.

Member Function Documentation

◆ BeginFrame()

virtual bool LLGL::XRSession::BeginFrame ( )

pure virtual

Begins a new XR frame. Must be called after WaitFrame().

Returns: True on success. On failure, the frame must be skipped (do not call EndFrame).

◆ CreateSwapChain()

virtual XRSwapChain * LLGL::XRSession::CreateSwapChain ( const XRSwapChainDescriptor & swapChainDesc )

pure virtual

Creates a new XR swap-chain.

Parameters

[in] swapChainDesc Specifies the swap-chain descriptor.

Returns: Pointer to the new XRSwapChain or null on failure (see XRSystem::GetReport).

Remarks: The session retains ownership of the swap-chain; releasing it through ReleaseSwapChain or destroying the session frees the underlying XR resources.

◆ EndFrame()

virtual bool LLGL::XRSession::EndFrame	(	float	nearZ,
		float	farZ,
		ArrayView< XRSwapChain * >	swapChains )

pure virtual

Submits a frame to the runtime.

Parameters

[in]	nearZ	Near clipping plane (in meters) the application used to render this frame.
[in]	farZ	Far clipping plane (in metres) the application used to render this frame.
[in]	swapChains	One swap-chain per view, in the same order as XRSystem::GetViewConfigurations().

Returns: True on success.

Remarks: This submits a projection composition layer using the swap-chains' currently released images. If WaitFrame returned false in frameState.shouldRender, an empty layer set is submitted instead (the runtime still requires a paired EndFrame call).

◆ GetEnvironmentBlendMode()

virtual XREnvironmentBlendMode LLGL::XRSession::GetEnvironmentBlendMode ( ) const

pure virtual

Returns the environment blend mode the runtime selected for this session.

◆ GetNativeHandle()

virtual bool LLGL::XRSession::GetNativeHandle	(	void *	nativeHandle,
		std::size_t	nativeHandleSize )

pure virtual

Returns the native handle of this XR Session.

Parameters

[out]	nativeHandle	Pointer to the backend-specific native handle structure. Obtain it from `#include <LLGL/Backend/OpenXR/NativeHandle.h>`.
[in]	nativeHandleSize	Size (in bytes) of the native handle structure.

Returns: True if the native handle was successfully retrieved.

See also: OpenXR::SessionNativeHandle

◆ GetReport()

virtual const Report * LLGL::XRSession::GetReport ( ) const

pure virtual

Returns a pointer to the report or null if there is none.

Remarks: Indicates errors from a previous session operation.

See also: Report

◆ GetState()

virtual XRSessionState LLGL::XRSession::GetState ( ) const

pure virtual

Returns the current runtime-reported session state.

◆ GetSupportedColorFormats()

virtual ArrayView< Format > LLGL::XRSession::GetSupportedColorFormats ( ) const

pure virtual

Returns the list of color formats supported by this session for swap-chains, in runtime-preferred order.

Remarks: The application should pick the first format that satisfies its rendering needs.

See also: CreateSwapChain

◆ GetSupportedDepthFormats()

virtual ArrayView< Format > LLGL::XRSession::GetSupportedDepthFormats ( ) const

pure virtual

Returns the list of depth-stencil formats supported by this session for swap-chains, in runtime-preferred order.

Remarks: Empty if the runtime doesn't support depth swap-chain submission (i.e. XR_KHR_composition_layer_depth is unavailable). When non-empty, pass the chosen format in XRSwapChainDescriptor::depthStencilFormat to have the swap-chain submit depth to the runtime for reprojection; otherwise the swap-chain falls back to a private depth texture that is not submitted.

See also: CreateSwapChain; XRSwapChainDescriptor::depthStencilFormat

◆ GetViewState()

virtual bool LLGL::XRSession::GetViewState ( DynamicVector< XRViewPose > & viewsOut )

pure virtual

Sample and return the latest predicted poses for the session's views.

Parameters

[out] viewsOut Receives the view poses and projection parameters. The size of this array matches the view count returned by XRSystem::GetViewConfigurations().

Returns: True on success.

Remarks: Each time this is called, the runtime updates the view poses based on the latest predicted display time. The application should call this at least once per frame after WaitFrame() to get the latest view poses for rendering and reprojection. If EndFrame is called with a non-empty swap-chain array, the runtime also uses these poses for reprojection of the submitted layer.

◆ IsRunning()

virtual bool LLGL::XRSession::IsRunning ( ) const

pure virtual

Returns true if the session has been signalled ready by the runtime and BeginFrame may be invoked.

Remarks: This becomes true after the runtime transitions to XRSessionState::Ready. Most applications should not call BeginFrame/EndFrame while this returns false.

◆ Release()

virtual void LLGL::XRSession::Release ( XRSwapChain & swapChain )

pure virtual

Releases the specified swap-chain. After this call, the specified object must no longer be used.

◆ WaitFrame()

virtual bool LLGL::XRSession::WaitFrame ( XRFrameState & frameState )

pure virtual

Waits for the previous frame to finish and retrieves the next frame state. Must be called before BeginFrame at the beginning of the app's update.

Parameters

[out] frameState Receives the predicted display time and a flag indicating whether the application should render.

Returns: True on success

The documentation for this class was generated from the following file:

XRSession.h

Public Member Functions

Protected Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ~XRSession()

◆ XRSession()

Member Function Documentation

◆ BeginFrame()

◆ CreateSwapChain()

◆ EndFrame()

◆ GetEnvironmentBlendMode()

◆ GetNativeHandle()

◆ GetReport()

◆ GetState()

◆ GetSupportedColorFormats()

◆ GetSupportedDepthFormats()

◆ GetViewState()

◆ IsRunning()

◆ Release()

◆ WaitFrame()