Base class for GL viewers.

Provides a basic scene management and a small set of control variables (camera, LOD, style, clip) that are used by the scene classes. Renering wrappers are available but minimal.

There is no concept of GL-context here ... we just draw into whatever is set from outside.

Development notes:

Each viewer automatically creates a TGLRnrCtx and passes it down all render functions.

Definition at line 36 of file TGLViewerBase.h.

Public Member Functions
	TGLViewerBase ()

virtual	~TGLViewerBase ()
	Destructor.

virtual void	AddOverlayElement (TGLOverlayElement *el)
	Add overlay element.

TGLSceneInfo *	AddScene (TGLSceneBase *scene)
	Add new scene, appropriate scene-info is created.

virtual void	Changed ()

TGLClip *	Clip () const

virtual void	DeleteOverlayAnnotations ()
	Delete overlay elements that are annotations.

virtual void	DeleteOverlayElements (TGLOverlayElement::ERole r)
	Delete overlay elements.

Bool_t	FindClosestOpaqueRecord (TGLSelectRecord &rec, Int_t &recIdx)
	Find next select record that can be resolved and whose result is not transparent, starting from position 'recIdx'.

Bool_t	FindClosestOverlayRecord (TGLOvlSelectRecord &rec, Int_t &recIdx)
	Find next overlay-select record that can be resolved, starting from position 'recIdx'.

Bool_t	FindClosestRecord (TGLSelectRecord &rec, Int_t &recIdx)
	Find next select record that can be resolved, starting from position 'recIdx'.

TGLLogicalShape *	FindLogicalInScenes (TObject *id)
	Find logical-shape representing object id in the list of scenes.

TGLRnrCtx *	GetRnrCtx () const

TGLSceneInfo *	GetSceneInfo (TGLSceneBase *scene)
	Find scene-info corresponding to scene.

virtual TClass *	IsA () const

virtual Bool_t	IsChanged () const

virtual const char *	LockIdStr () const
	Name to print in locking output.

Short_t	LOD () const

virtual void	MergeSceneBBoxes (TGLBoundingBox &bbox)
	Merge bounding-boxes of all active registered scenes.

Float_t	OLLineW () const

virtual void	PostRender ()
	Function called after rendering is finished.

virtual void	PostRenderOverlaySelection ()
	Perform cleanup after overlay selection.

virtual void	PreRender ()
	Initialize render-context, setup camera, GL, render-area.

virtual void	PreRenderOverlaySelection ()
	Perform minimal initialization for overlay selection.

const TGLBoundingBox &	RefOverallBoundingBox () const

void	RemoveAllScenes ()
	Remove all scenes from the viewer, their scene-infos are deleted.

virtual void	RemoveOverlayElement (TGLOverlayElement *el)
	Remove overlay element.

void	RemoveScene (TGLSceneBase *scene)
	Remove scene from the viewer, its scene-info is deleted.

virtual void	Render ()
	Render all scenes.

virtual void	RenderNonSelected ()
	Render non-selected objects from all scenes.

virtual void	RenderOpaque (Bool_t rnr_non_selected=kTRUE, Bool_t rnr_selected=kTRUE)
	Render opaque objects from all scenes.

virtual void	RenderOverlay (Int_t state, Bool_t selection)
	Render overlay objects.

virtual void	RenderSelected ()
	Render selected objects from all scenes.

virtual void	RenderSelectedForHighlight ()
	Render selected objects from all scenes for highlight.

virtual void	RenderTransparent (Bool_t rnr_non_selected=kTRUE, Bool_t rnr_selected=kTRUE)
	Render transparent objects from all scenes.

virtual void	ResetSceneInfos ()
	Force rebuild of view-dependent scene-info structures.

Bool_t	ResolveSelectRecord (TGLSelectRecord &rec, Int_t recIdx)
	Process selection record on buffer-position 'recIdx' and fill the data into 'rec'.

TGLRnrCtx &	RnrCtx () const

void	SceneDestructing (TGLSceneBase *scene)
	Remove scene, its scene-info is deleted.

void	SetClip (TGLClip *p)

void	SetLOD (Short_t lod)

void	SetOLLineW (Float_t w)

void	SetStyle (Short_t st)

void	SetWFLineW (Float_t w)

virtual void	Streamer (TBuffer &)

void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

Short_t	Style () const

Float_t	WFLineW () const

Public Member Functions inherited from TGLLockable
	TGLLockable ()

virtual	~TGLLockable ()

ELock	CurrentLock () const

Bool_t	IsDrawOrSelectLock () const

Bool_t	IsLocked () const

Bool_t	ReleaseLock (ELock lock) const
	Release current lock, make sure it the same as the 'lock' argument.

void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

Bool_t	TakeLock (ELock lock) const
	Lock the object in mode 'lock'.

Static Public Member Functions
static TClass *	Class ()

static const char *	Class_Name ()

static constexpr Version_t	Class_Version ()

static const char *	DeclFileName ()

Static Public Member Functions inherited from TGLLockable
static TClass *	Class ()

static const char *	Class_Name ()

static constexpr Version_t	Class_Version ()

static const char *	DeclFileName ()

static const char *	LockName (ELock lock)
	Return name-string for given lock-type.

static Bool_t	LockValid (ELock lock)
	Test if lock is a valid type to take/release.

Protected Types
typedef OverlayElmVec_t::iterator	OverlayElmVec_i

typedef std::vector< TGLOverlayElement * >	OverlayElmVec_t

typedef SceneInfoList_t::iterator	SceneInfoList_i

typedef std::list< TGLSceneInfo * >	SceneInfoList_t

typedef SceneInfoVec_t::iterator	SceneInfoVec_i

typedef std::vector< TGLSceneInfo * >	SceneInfoVec_t

typedef void(TGLSceneBase::*	SubRender_foo) (TGLRnrCtx &)

Protected Member Functions
SceneInfoList_i	FindScene (TGLSceneBase *scene)
	Find scene-info corresponding to scene.

virtual void	SetupClipObject ()
	Setup clip-object. Protected virtual method.

void	SubRenderScenes (SubRender_foo render_foo)
	Call sub-rendering function render_foo on all currently visible scenes.

Protected Attributes
TGLCamera *	fCamera

Bool_t	fChanged

TGLClip *	fClip

Short_t	fLOD

Float_t	fOLLineW

TGLBoundingBox	fOverallBoundingBox

OverlayElmVec_t	fOverlay

Bool_t	fResetSceneInfosOnRender

TGLRnrCtx *	fRnrCtx

SceneInfoList_t	fScenes

Short_t	fStyle

SceneInfoVec_t	fVisScenes

Float_t	fWFLineW

Protected Attributes inherited from TGLLockable
ELock	fLock

Private Member Functions
	TGLViewerBase (const TGLViewerBase &)

TGLViewerBase &	operator= (const TGLViewerBase &)

Additional Inherited Members
Public Types inherited from TGLLockable
enum	ELock { kUnlocked , kDrawLock , kSelectLock , kModifyLock }

#include <TGLViewerBase.h>

Inheritance diagram for TGLViewerBase:

[legend]

Member Typedef Documentation

◆ OverlayElmVec_i

typedef OverlayElmVec_t::iterator TGLViewerBase::OverlayElmVec_i

protected

Definition at line 50 of file TGLViewerBase.h.

◆ OverlayElmVec_t

typedef std::vector<TGLOverlayElement*> TGLViewerBase::OverlayElmVec_t

protected

Definition at line 49 of file TGLViewerBase.h.

◆ SceneInfoList_i

typedef SceneInfoList_t::iterator TGLViewerBase::SceneInfoList_i

protected

Definition at line 44 of file TGLViewerBase.h.

◆ SceneInfoList_t

typedef std::list<TGLSceneInfo*> TGLViewerBase::SceneInfoList_t

protected

Definition at line 43 of file TGLViewerBase.h.

◆ SceneInfoVec_i

typedef SceneInfoVec_t::iterator TGLViewerBase::SceneInfoVec_i

protected

Definition at line 47 of file TGLViewerBase.h.

◆ SceneInfoVec_t

typedef std::vector<TGLSceneInfo*> TGLViewerBase::SceneInfoVec_t

protected

Definition at line 46 of file TGLViewerBase.h.

◆ SubRender_foo

typedef void(TGLSceneBase::* TGLViewerBase::SubRender_foo) (TGLRnrCtx &)

protected

Definition at line 54 of file TGLViewerBase.h.

Constructor & Destructor Documentation

◆ TGLViewerBase() [1/2]

TGLViewerBase::TGLViewerBase ( const TGLViewerBase & )

private

◆ TGLViewerBase() [2/2]

TGLViewerBase::TGLViewerBase ( )

Definition at line 54 of file TGLViewerBase.cxx.

◆ ~TGLViewerBase()

TGLViewerBase::~TGLViewerBase ( )

virtual

Destructor.

Definition at line 77 of file TGLViewerBase.cxx.

Member Function Documentation

◆ AddOverlayElement()

void TGLViewerBase::AddOverlayElement ( TGLOverlayElement * el )

virtual

Add overlay element.

Definition at line 211 of file TGLViewerBase.cxx.

◆ AddScene()

TGLSceneInfo * TGLViewerBase::AddScene ( TGLSceneBase * scene )

Add new scene, appropriate scene-info is created.

Definition at line 116 of file TGLViewerBase.cxx.

◆ Changed()

virtual void TGLViewerBase::Changed ( )

inlinevirtual

Definition at line 121 of file TGLViewerBase.h.

◆ Class()

static TClass * TGLViewerBase::Class ( )

static

Returns: TClass describing this class

◆ Class_Name()

static const char * TGLViewerBase::Class_Name ( )

static

Returns: Name of this class

◆ Class_Version()

static constexpr Version_t TGLViewerBase::Class_Version ( )

inlinestaticconstexpr

Returns: Version of this class

Definition at line 161 of file TGLViewerBase.h.

◆ Clip()

TGLClip * TGLViewerBase::Clip ( ) const

inline

Definition at line 104 of file TGLViewerBase.h.

◆ DeclFileName()

static const char * TGLViewerBase::DeclFileName ( )

inlinestatic

Returns: Name of the file containing the class declaration

Definition at line 161 of file TGLViewerBase.h.

◆ DeleteOverlayAnnotations()

void TGLViewerBase::DeleteOverlayAnnotations ( )

virtual

Delete overlay elements that are annotations.

Definition at line 231 of file TGLViewerBase.cxx.

◆ DeleteOverlayElements()

void TGLViewerBase::DeleteOverlayElements ( TGLOverlayElement::ERole r )

virtual

Delete overlay elements.

Definition at line 239 of file TGLViewerBase.cxx.

◆ FindClosestOpaqueRecord()

Bool_t TGLViewerBase::FindClosestOpaqueRecord	(	TGLSelectRecord &	rec,
		Int_t &	recIdx
	)

Find next select record that can be resolved and whose result is not transparent, starting from position 'recIdx'.

'recIdx' is passed as reference and points to found record in the buffer.

Definition at line 642 of file TGLViewerBase.cxx.

◆ FindClosestOverlayRecord()

Bool_t TGLViewerBase::FindClosestOverlayRecord	(	TGLOvlSelectRecord &	rec,
		Int_t &	recIdx
	)

Find next overlay-select record that can be resolved, starting from position 'recIdx'.

'recIdx' is passed as reference and points to found record in the buffer.

Definition at line 660 of file TGLViewerBase.cxx.

◆ FindClosestRecord()

Bool_t TGLViewerBase::FindClosestRecord	(	TGLSelectRecord &	rec,
		Int_t &	recIdx
	)

Find next select record that can be resolved, starting from position 'recIdx'.

'recIdx' is passed as reference and points to found record in the buffer.

Definition at line 624 of file TGLViewerBase.cxx.

◆ FindLogicalInScenes()

TGLLogicalShape * TGLViewerBase::FindLogicalInScenes ( TObject * id )

Find logical-shape representing object id in the list of scenes.

Return 0 if not found.

Definition at line 197 of file TGLViewerBase.cxx.

◆ FindScene()

TGLViewerBase::SceneInfoList_i TGLViewerBase::FindScene ( TGLSceneBase * scene )

protected

Find scene-info corresponding to scene.

Definition at line 106 of file TGLViewerBase.cxx.

◆ GetRnrCtx()

TGLRnrCtx * TGLViewerBase::GetRnrCtx ( ) const

inline

Definition at line 158 of file TGLViewerBase.h.

◆ GetSceneInfo()

TGLSceneInfo * TGLViewerBase::GetSceneInfo ( TGLSceneBase * scene )

Find scene-info corresponding to scene.

Definition at line 184 of file TGLViewerBase.cxx.

◆ IsA()

virtual TClass * TGLViewerBase::IsA ( ) const

inlinevirtual

Returns: TClass describing current object

Reimplemented from TGLLockable.

Reimplemented in TGLEmbeddedViewer, TGLSAViewer, and TGLViewer.

Definition at line 161 of file TGLViewerBase.h.

◆ IsChanged()

virtual Bool_t TGLViewerBase::IsChanged ( ) const

inlinevirtual

Definition at line 122 of file TGLViewerBase.h.

◆ LockIdStr()

const char * TGLViewerBase::LockIdStr ( ) const

virtual

Name to print in locking output.

Reimplemented from TGLLockable.

Definition at line 93 of file TGLViewerBase.cxx.

◆ LOD()

Short_t TGLViewerBase::LOD ( ) const

inline

Definition at line 107 of file TGLViewerBase.h.

◆ MergeSceneBBoxes()

void TGLViewerBase::MergeSceneBBoxes ( TGLBoundingBox & bbox )

virtual

Merge bounding-boxes of all active registered scenes.

Definition at line 278 of file TGLViewerBase.cxx.

◆ OLLineW()

Float_t TGLViewerBase::OLLineW ( ) const

inline

Definition at line 115 of file TGLViewerBase.h.

◆ operator=()

TGLViewerBase & TGLViewerBase::operator= ( const TGLViewerBase & )

private

◆ PostRender()

void TGLViewerBase::PostRender ( )

virtual

Function called after rendering is finished.

Here we just unlock the scenes.

Reimplemented in TGLViewer.

Definition at line 547 of file TGLViewerBase.cxx.

◆ PostRenderOverlaySelection()

void TGLViewerBase::PostRenderOverlaySelection ( )

virtual

Perform cleanup after overlay selection.

Definition at line 574 of file TGLViewerBase.cxx.

◆ PreRender()

void TGLViewerBase::PreRender ( )

virtual

Initialize render-context, setup camera, GL, render-area.

Check and lock scenes, determine their visibility.

Reimplemented in TGLViewer.

Definition at line 311 of file TGLViewerBase.cxx.

◆ PreRenderOverlaySelection()

void TGLViewerBase::PreRenderOverlaySelection ( )

virtual

Perform minimal initialization for overlay selection.

Here we assume that scene has already been drawn and that camera and overall bounding box are ok. Scenes are not locked.

Definition at line 566 of file TGLViewerBase.cxx.

◆ RefOverallBoundingBox()

const TGLBoundingBox & TGLViewerBase::RefOverallBoundingBox ( ) const

inline

Definition at line 126 of file TGLViewerBase.h.

◆ RemoveAllScenes()

void TGLViewerBase::RemoveAllScenes ( )

Remove all scenes from the viewer, their scene-infos are deleted.

Definition at line 152 of file TGLViewerBase.cxx.

◆ RemoveOverlayElement()

void TGLViewerBase::RemoveOverlayElement ( TGLOverlayElement * el )

virtual

Remove overlay element.

Reimplemented in TGLViewer.

Definition at line 220 of file TGLViewerBase.cxx.

◆ RemoveScene()

void TGLViewerBase::RemoveScene ( TGLSceneBase * scene )

Remove scene from the viewer, its scene-info is deleted.

Definition at line 135 of file TGLViewerBase.cxx.

◆ Render()

void TGLViewerBase::Render ( )

virtual

Render all scenes.

This is done in two main passes:

render opaque objects from all scenes
render transparent objects from all scenes

Reimplemented in TGLViewer.

Definition at line 423 of file TGLViewerBase.cxx.

◆ RenderNonSelected()

void TGLViewerBase::RenderNonSelected ( )

virtual

Render non-selected objects from all scenes.

Definition at line 432 of file TGLViewerBase.cxx.

◆ RenderOpaque()

void TGLViewerBase::RenderOpaque	(	Bool_t	rnr_non_selected = `kTRUE`,
		Bool_t	rnr_selected = `kTRUE`
	)

virtual

Render opaque objects from all scenes.

Definition at line 488 of file TGLViewerBase.cxx.

◆ RenderOverlay()

void TGLViewerBase::RenderOverlay	(	Int_t	state,
		Bool_t	selection
	)

virtual

Render overlay objects.

Definition at line 528 of file TGLViewerBase.cxx.

◆ RenderSelected()

void TGLViewerBase::RenderSelected ( )

virtual

Render selected objects from all scenes.

Definition at line 450 of file TGLViewerBase.cxx.

◆ RenderSelectedForHighlight()

void TGLViewerBase::RenderSelectedForHighlight ( )

virtual

Render selected objects from all scenes for highlight.

Definition at line 468 of file TGLViewerBase.cxx.

◆ RenderTransparent()

void TGLViewerBase::RenderTransparent	(	Bool_t	rnr_non_selected = `kTRUE`,
		Bool_t	rnr_selected = `kTRUE`
	)

virtual

Render transparent objects from all scenes.

Definition at line 505 of file TGLViewerBase.cxx.

◆ ResetSceneInfos()

void TGLViewerBase::ResetSceneInfos ( )

virtual

Force rebuild of view-dependent scene-info structures.

This should be called before calling render (draw/select) if something that affects camera interest has been changed.

Definition at line 265 of file TGLViewerBase.cxx.

◆ ResolveSelectRecord()

Bool_t TGLViewerBase::ResolveSelectRecord	(	TGLSelectRecord &	rec,
		Int_t	recIdx
	)

Process selection record on buffer-position 'recIdx' and fill the data into 'rec'.

Returns TRUE if scene was demangled and an object identified. When FALSE is returned it is still possible that scene has been identified. Check for this if interested in scene-selection.

The select-buffer is taken form fRnrCtx.

Definition at line 601 of file TGLViewerBase.cxx.

◆ RnrCtx()

TGLRnrCtx & TGLViewerBase::RnrCtx ( ) const

inline

Definition at line 159 of file TGLViewerBase.h.

◆ SceneDestructing()

void TGLViewerBase::SceneDestructing ( TGLSceneBase * scene )

Remove scene, its scene-info is deleted.

Called from scene that is being destroyed while still holding viewer references.

Definition at line 169 of file TGLViewerBase.cxx.

◆ SetClip()

void TGLViewerBase::SetClip ( TGLClip * p )

inline

Definition at line 105 of file TGLViewerBase.h.

◆ SetLOD()

void TGLViewerBase::SetLOD ( Short_t lod )

inline

Definition at line 108 of file TGLViewerBase.h.

◆ SetOLLineW()

void TGLViewerBase::SetOLLineW ( Float_t w )

inline

Definition at line 116 of file TGLViewerBase.h.

◆ SetStyle()

void TGLViewerBase::SetStyle ( Short_t st )

inline

Definition at line 111 of file TGLViewerBase.h.

◆ SetupClipObject()

void TGLViewerBase::SetupClipObject ( )

protectedvirtual

Setup clip-object. Protected virtual method.

Reimplemented in TGLViewer.

Definition at line 299 of file TGLViewerBase.cxx.

◆ SetWFLineW()

void TGLViewerBase::SetWFLineW ( Float_t w )

inline

Definition at line 114 of file TGLViewerBase.h.

◆ Streamer()

virtual void TGLViewerBase::Streamer ( TBuffer & )

virtual

Reimplemented from TGLLockable.

Reimplemented in TGLEmbeddedViewer, TGLSAViewer, and TGLViewer.

◆ StreamerNVirtual()

void TGLViewerBase::StreamerNVirtual ( TBuffer & ClassDef_StreamerNVirtual_b )

inline

Definition at line 161 of file TGLViewerBase.h.

◆ Style()

Short_t TGLViewerBase::Style ( ) const

inline

Definition at line 110 of file TGLViewerBase.h.

◆ SubRenderScenes()

void TGLViewerBase::SubRenderScenes ( SubRender_foo render_foo )

protected

Call sub-rendering function render_foo on all currently visible scenes.

Definition at line 400 of file TGLViewerBase.cxx.

◆ WFLineW()

Float_t TGLViewerBase::WFLineW ( ) const

inline

Definition at line 113 of file TGLViewerBase.h.

Member Data Documentation

◆ fCamera

TGLCamera* TGLViewerBase::fCamera

protected

Definition at line 64 of file TGLViewerBase.h.

◆ fChanged

Bool_t TGLViewerBase::fChanged

protected

Definition at line 72 of file TGLViewerBase.h.

◆ fClip

TGLClip* TGLViewerBase::fClip

protected

Definition at line 65 of file TGLViewerBase.h.

◆ fLOD

Short_t TGLViewerBase::fLOD

protected

Definition at line 66 of file TGLViewerBase.h.

◆ fOLLineW

Float_t TGLViewerBase::fOLLineW

protected

Definition at line 69 of file TGLViewerBase.h.

◆ fOverallBoundingBox

TGLBoundingBox TGLViewerBase::fOverallBoundingBox

protected

Definition at line 77 of file TGLViewerBase.h.

◆ fOverlay

OverlayElmVec_t TGLViewerBase::fOverlay

protected

Definition at line 79 of file TGLViewerBase.h.

◆ fResetSceneInfosOnRender

Bool_t TGLViewerBase::fResetSceneInfosOnRender

protected

Definition at line 71 of file TGLViewerBase.h.

◆ fRnrCtx

TGLRnrCtx* TGLViewerBase::fRnrCtx

protected

Definition at line 62 of file TGLViewerBase.h.

◆ fScenes

SceneInfoList_t TGLViewerBase::fScenes

protected

Definition at line 74 of file TGLViewerBase.h.

◆ fStyle

Short_t TGLViewerBase::fStyle

protected

Definition at line 67 of file TGLViewerBase.h.

◆ fVisScenes

SceneInfoVec_t TGLViewerBase::fVisScenes

protected

Definition at line 75 of file TGLViewerBase.h.

◆ fWFLineW

Float_t TGLViewerBase::fWFLineW

protected

Definition at line 68 of file TGLViewerBase.h.

Libraries for TGLViewerBase:

[legend]

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

graf3d/gl/inc/TGLViewerBase.h
graf3d/gl/src/TGLViewerBase.cxx

Public Member Functions

Static Public Member Functions

Protected Types

Protected Member Functions

Protected Attributes

Private Member Functions

Additional Inherited Members

Member Typedef Documentation

◆ OverlayElmVec_i

◆ OverlayElmVec_t

◆ SceneInfoList_i

◆ SceneInfoList_t

◆ SceneInfoVec_i

◆ SceneInfoVec_t

◆ SubRender_foo

Constructor & Destructor Documentation

◆ TGLViewerBase() [1/2]

◆ TGLViewerBase() [2/2]

◆ ~TGLViewerBase()

Member Function Documentation

◆ AddOverlayElement()

◆ AddScene()

◆ Changed()

◆ Class()

◆ Class_Name()

◆ Class_Version()

◆ Clip()

◆ DeclFileName()

◆ DeleteOverlayAnnotations()

◆ DeleteOverlayElements()

◆ FindClosestOpaqueRecord()

◆ FindClosestOverlayRecord()

◆ FindClosestRecord()

◆ FindLogicalInScenes()

◆ FindScene()

◆ GetRnrCtx()

◆ GetSceneInfo()

◆ IsA()

◆ IsChanged()

◆ LockIdStr()

◆ LOD()

◆ MergeSceneBBoxes()

◆ OLLineW()

◆ operator=()

◆ PostRender()

◆ PostRenderOverlaySelection()

◆ PreRender()

◆ PreRenderOverlaySelection()

◆ RefOverallBoundingBox()

◆ RemoveAllScenes()

◆ RemoveOverlayElement()

◆ RemoveScene()

◆ Render()

◆ RenderNonSelected()

◆ RenderOpaque()

◆ RenderOverlay()

◆ RenderSelected()

◆ RenderSelectedForHighlight()

◆ RenderTransparent()

◆ ResetSceneInfos()

◆ ResolveSelectRecord()

◆ RnrCtx()

◆ SceneDestructing()

◆ SetClip()

◆ SetLOD()

◆ SetOLLineW()

◆ SetStyle()

◆ SetupClipObject()

◆ SetWFLineW()

◆ Streamer()

◆ StreamerNVirtual()

◆ Style()

◆ SubRenderScenes()

◆ WFLineW()

Member Data Documentation

◆ fCamera

◆ fChanged

◆ fClip

◆ fLOD

◆ fOLLineW