vtkWebGPUComputeOcclusionCuller Class Reference

This culler does both frustum culling and occlusion culling. More...

#include <vtkWebGPUComputeOcclusionCuller.h>

Inheritance diagram for vtkWebGPUComputeOcclusionCuller:

Collaboration diagram for vtkWebGPUComputeOcclusionCuller:

Public Types
typedef vtkCuller	Superclass
Public Types inherited from vtkCuller
typedef vtkObject	Superclass

Public Member Functions
virtual vtkTypeBool	IsA (const char *type)
	Return 1 if this class is the same type of (or a subclass of) the named class.
vtkWebGPUComputeOcclusionCuller *	NewInstance () const
void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses.
void	SetRenderWindow (vtkWebGPURenderWindow *webGpuRenderWindow)
	Sets which render window this occlusion culler is going to work on.
double	Cull (vtkRenderer *renderer, vtkProp **propList, int &listLength, int &initialized) override
	Culls props and returns the number of props that still need to be rendered after the culling.
Public Member Functions inherited from vtkCuller
virtual vtkTypeBool	IsA (const char *type)
	Return 1 if this class is the same type of (or a subclass of) the named class.
vtkCuller *	NewInstance () const
void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses.
virtual double	Cull (vtkRenderer *ren, vtkProp **propList, int &listLength, int &initialized)=0
	This is called outside the render loop by vtkRenderer.
Public Member Functions inherited from vtkObject
	vtkBaseTypeMacro (vtkObject, vtkObjectBase)
virtual void	DebugOn ()
	Turn debugging output on.
virtual void	DebugOff ()
	Turn debugging output off.
bool	GetDebug ()
	Get the value of the debug flag.
void	SetDebug (bool debugFlag)
	Set the value of the debug flag.
virtual void	Modified ()
	Update the modification time for this object.
virtual vtkMTimeType	GetMTime ()
	Return this object's modified time.
void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses.
void	RemoveObserver (unsigned long tag)
void	RemoveObservers (unsigned long event)
void	RemoveObservers (const char *event)
void	RemoveAllObservers ()
vtkTypeBool	HasObserver (unsigned long event)
vtkTypeBool	HasObserver (const char *event)
vtkTypeBool	InvokeEvent (unsigned long event)
vtkTypeBool	InvokeEvent (const char *event)
std::string	GetObjectDescription () const override
	The object description printed in messages and PrintSelf output.
unsigned long	AddObserver (unsigned long event, vtkCommand *, float priority=0.0f)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
unsigned long	AddObserver (const char *event, vtkCommand *, float priority=0.0f)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
vtkCommand *	GetCommand (unsigned long tag)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
void	RemoveObserver (vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
void	RemoveObservers (unsigned long event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
void	RemoveObservers (const char *event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
vtkTypeBool	HasObserver (unsigned long event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
vtkTypeBool	HasObserver (const char *event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object.
template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::*callback)(), float priority=0.0f)
	Overloads to AddObserver that allow developers to add class member functions as callbacks for events.
template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::*callback)(vtkObject *, unsigned long, void *), float priority=0.0f)
	Overloads to AddObserver that allow developers to add class member functions as callbacks for events.
template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, bool(T::*callback)(vtkObject *, unsigned long, void *), float priority=0.0f)
	Allow user to set the AbortFlagOn() with the return value of the callback method.
vtkTypeBool	InvokeEvent (unsigned long event, void *callData)
	This method invokes an event and return whether the event was aborted or not.
vtkTypeBool	InvokeEvent (const char *event, void *callData)
	This method invokes an event and return whether the event was aborted or not.
virtual void	SetObjectName (const std::string &objectName)
	Set/get the name of this object for reporting purposes.
virtual std::string	GetObjectName () const
	Set/get the name of this object for reporting purposes.
Public Member Functions inherited from vtkObjectBase
const char *	GetClassName () const
	Return the class name as a string.
virtual std::string	GetObjectDescription () const
	The object description printed in messages and PrintSelf output.
virtual vtkTypeBool	IsA (const char *name)
	Return 1 if this class is the same type of (or a subclass of) the named class.
virtual vtkIdType	GetNumberOfGenerationsFromBase (const char *name)
	Given the name of a base class of this class type, return the distance of inheritance between this class type and the named class (how many generations of inheritance are there between this class and the named class).
virtual void	Delete ()
	Delete a VTK object.
virtual void	FastDelete ()
	Delete a reference to this object.
void	InitializeObjectBase ()
void	Print (ostream &os)
	Print an object to an ostream.
void	Register (vtkObjectBase *o)
	Increase the reference count (mark as used by another object).
virtual void	UnRegister (vtkObjectBase *o)
	Decrease the reference count (release by another object).
int	GetReferenceCount ()
	Return the current reference count of this object.
void	SetReferenceCount (int)
	Sets the reference count.
bool	GetIsInMemkind () const
	A local state flag that remembers whether this object lives in the normal or extended memory space.
virtual void	PrintHeader (ostream &os, vtkIndent indent)
	Methods invoked by print to print information about the object including superclasses.
virtual void	PrintTrailer (ostream &os, vtkIndent indent)
	Methods invoked by print to print information about the object including superclasses.
virtual bool	UsesGarbageCollector () const
	Indicate whether the class uses vtkGarbageCollector or not.

Static Public Member Functions
static vtkTypeBool	IsTypeOf (const char *type)
static vtkWebGPUComputeOcclusionCuller *	SafeDownCast (vtkObjectBase *o)
static vtkWebGPUComputeOcclusionCuller *	New ()
Static Public Member Functions inherited from vtkCuller
static vtkTypeBool	IsTypeOf (const char *type)
static vtkCuller *	SafeDownCast (vtkObjectBase *o)
Static Public Member Functions inherited from vtkObject
static vtkObject *	New ()
	Create an object with Debug turned off, modified time initialized to zero, and reference counting on.
static void	BreakOnError ()
	This method is called when vtkErrorMacro executes.
static void	SetGlobalWarningDisplay (vtkTypeBool val)
	This is a global flag that controls whether any debug, warning or error messages are displayed.
static void	GlobalWarningDisplayOn ()
	This is a global flag that controls whether any debug, warning or error messages are displayed.
static void	GlobalWarningDisplayOff ()
	This is a global flag that controls whether any debug, warning or error messages are displayed.
static vtkTypeBool	GetGlobalWarningDisplay ()
	This is a global flag that controls whether any debug, warning or error messages are displayed.
Static Public Member Functions inherited from vtkObjectBase
static vtkTypeBool	IsTypeOf (const char *name)
	Return 1 if this class type is the same type of (or a subclass of) the named class.
static vtkIdType	GetNumberOfGenerationsFromBaseType (const char *name)
	Given a the name of a base class of this class type, return the distance of inheritance between this class type and the named class (how many generations of inheritance are there between this class and the named class).
static vtkObjectBase *	New ()
	Create an object with Debug turned off, modified time initialized to zero, and reference counting on.
static void	SetMemkindDirectory (const char *directoryname)
	The name of a directory, ideally mounted -o dax, to memory map an extended memory space within.
static bool	GetUsingMemkind ()
	A global state flag that controls whether vtkObjects are constructed in the usual way (the default) or within the extended memory space.

Protected Member Functions
virtual vtkObjectBase *	NewInstanceInternal () const
	vtkWebGPUComputeOcclusionCuller ()
	~vtkWebGPUComputeOcclusionCuller () override
Protected Member Functions inherited from vtkCuller
virtual vtkObjectBase *	NewInstanceInternal () const
	vtkCuller ()
	~vtkCuller () override
Protected Member Functions inherited from vtkObject
	vtkObject ()
	~vtkObject () override
void	RegisterInternal (vtkObjectBase *, vtkTypeBool check) override
void	UnRegisterInternal (vtkObjectBase *, vtkTypeBool check) override
void	InternalGrabFocus (vtkCommand *mouseEvents, vtkCommand *keypressEvents=nullptr)
	These methods allow a command to exclusively grab all events.
void	InternalReleaseFocus ()
	These methods allow a command to exclusively grab all events.
Protected Member Functions inherited from vtkObjectBase
	vtkObjectBase ()
virtual	~vtkObjectBase ()
virtual void	RegisterInternal (vtkObjectBase *, vtkTypeBool check)
virtual void	UnRegisterInternal (vtkObjectBase *, vtkTypeBool check)
virtual void	ReportReferences (vtkGarbageCollector *)
virtual void	ObjectFinalize ()
	vtkObjectBase (const vtkObjectBase &)
void	operator= (const vtkObjectBase &)

Additional Inherited Members
Static Protected Member Functions inherited from vtkObjectBase
static vtkMallocingFunction	GetCurrentMallocFunction ()
static vtkReallocingFunction	GetCurrentReallocFunction ()
static vtkFreeingFunction	GetCurrentFreeFunction ()
static vtkFreeingFunction	GetAlternateFreeFunction ()
Protected Attributes inherited from vtkObject
bool	Debug
vtkTimeStamp	MTime
vtkSubjectHelper *	SubjectHelper
std::string	ObjectName
Protected Attributes inherited from vtkObjectBase
std::atomic< int32_t >	ReferenceCount
vtkWeakPointerBase **	WeakPointers

Detailed Description

This culler does both frustum culling and occlusion culling.

Occlusion culling culls props that are occluded (behind) other props and that are not visible to the camera because of that.

This implementation uses the two-pass hierarchical z-buffer approach.

This approach projects the bound of the actors onto the viewport and compares the depth of the projected region with a prepass depth buffer. This "prepass" depth buffer is built from the objects that were rendered last frame. These objects offer a good approximation of what objects will be visible this frame (assuming no brutal camera movements). To make the depth comparison between the quad of the actor (projection of its bounding box on the viewport) more efficient, a mipmap chain of the depth buffer is used. Without this mipmap chain, we would have to compare the depth of all the pixels (there could be dozens to hundreds of thousands depending on the screen-space size of the actor) of the projected bouding box of the actor against the depth buffer which would be way too expensive. Using a mipmap chain allows us to choose the right mipmap so that we only have to check a few (~4 +/- 2) pixels for the depth.

Resource for a general overview of the algorithm: https://medium.com/@mil_kru/two-pass-occlusion-culling-4100edcad501

Resource for non-power of two mipmap calculation: https://miketuritzin.com/post/hierarchical-depth-buffers/

To use this culler, simply instantiate it and set its RenderWindow (after Initialize() has been called on the RenderWindow()):

vtkNew<vtkWebGPUComputeOcclusionCuller> webgpuOcclusionCuller;

renWin->Initialize(); webgpuOcclusionCuller->SetRenderWindow(renWin)

Then add it to the cullers of your renderer:

renderer->GetCullers()->AddItem(webgpuOcclusionCuller);

You may also want to remove the default CPU coverage culler of your renderer by calling :

renderer->GetCullers()->RemoveAllItems();

before adding the webgpuOcclusionCuller.

Warning

: In its current state, the compute occlusion culler is expected to fail if the WebGPU backend used is OpenGL. This is because OpenGL has its texture coordinate origin (0, 0) at the bottom left corner of the texture whereas the shader of the occlusion culler expects the (0, 0) of the texture to be in the top left corner. With OpenGL, this will cause reads into the depth buffer to be reversed along the Y axis and incorrect depth values will be read --> invalid culling.

Definition at line 68 of file vtkWebGPUComputeOcclusionCuller.h.

Member Typedef Documentation

Superclass

typedef vtkCuller vtkWebGPUComputeOcclusionCuller::Superclass

Definition at line 71 of file vtkWebGPUComputeOcclusionCuller.h.

Constructor & Destructor Documentation

vtkWebGPUComputeOcclusionCuller()

vtkWebGPUComputeOcclusionCuller::vtkWebGPUComputeOcclusionCuller ( )

protected

~vtkWebGPUComputeOcclusionCuller()

vtkWebGPUComputeOcclusionCuller::~vtkWebGPUComputeOcclusionCuller ( )

overrideprotected

Member Function Documentation

IsTypeOf()

static vtkTypeBool vtkWebGPUComputeOcclusionCuller::IsTypeOf ( const char *  type )

static

IsA()

virtual vtkTypeBool vtkWebGPUComputeOcclusionCuller::IsA ( const char *  name )

virtual

Return 1 if this class is the same type of (or a subclass of) the named class.

Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkCuller.

SafeDownCast()

static vtkWebGPUComputeOcclusionCuller * vtkWebGPUComputeOcclusionCuller::SafeDownCast ( vtkObjectBase *  o )

static

NewInstanceInternal()

virtual vtkObjectBase * vtkWebGPUComputeOcclusionCuller::NewInstanceInternal ( ) const

protectedvirtual

Reimplemented from vtkCuller.

NewInstance()

vtkWebGPUComputeOcclusionCuller * vtkWebGPUComputeOcclusionCuller::NewInstance

(

)

const

New()

static vtkWebGPUComputeOcclusionCuller * vtkWebGPUComputeOcclusionCuller::New ( )

static

PrintSelf()

void vtkWebGPUComputeOcclusionCuller::PrintSelf ( ostream &  os, vtkIndent  indent  )

overridevirtual

Methods invoked by print to print information about the object including superclasses.

Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkCuller.

SetRenderWindow()

void vtkWebGPUComputeOcclusionCuller::SetRenderWindow

(

vtkWebGPURenderWindow *

webGpuRenderWindow

)

Sets which render window this occlusion culler is going to work on.

Cull()

double vtkWebGPUComputeOcclusionCuller::Cull ( vtkRenderer *  renderer, vtkProp **  propList, int &  listLength, int &  initialized  )

overridevirtual

Culls props and returns the number of props that still need to be rendered after the culling.

Implements vtkCuller.

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

• Rendering/WebGPU/vtkWebGPUComputeOcclusionCuller.h