#include <Impostor.h>

Inheritance diagram for osgSim::Impostor:

Collaboration diagram for osgSim::Impostor:

Public Types
typedef std::vector < osg::ref_ptr< ImpostorSprite > >	ImpostorSpriteList

Public Types inherited from osg::LOD
enum	CenterMode { USE_BOUNDING_SPHERE_CENTER, USER_DEFINED_CENTER, UNION_OF_BOUNDING_SPHERE_AND_USER_DEFINED }

enum	RangeMode { DISTANCE_FROM_EYE_POINT, PIXEL_SIZE_ON_SCREEN }

typedef osg::BoundingSphere::vec_type	vec_type

typedef osg::BoundingSphere::value_type	value_type

typedef std::pair< float, float >	MinMaxPair

typedef std::vector< MinMaxPair >	RangeList

Public Types inherited from osg::Node
typedef std::vector< Group * >	ParentList

typedef unsigned int	NodeMask

typedef std::vector< std::string >	DescriptionList

Public Types inherited from osg::Object
enum	DataVariance { DYNAMIC, STATIC, UNSPECIFIED }

Public Member Functions
	Impostor ()

	Impostor (const Impostor &es, const osg::CopyOp &copyop=osg::CopyOp::SHALLOW_COPY)

	META_Node (osgSim, Impostor)

virtual void	traverse (osg::NodeVisitor &nv)

void	setImpostorThreshold (float distance)

float	getImpostorThreshold () const

void	setImpostorThresholdToBound (float ratio=1.0f)

ImpostorSprite *	findBestImpostorSprite (unsigned int contextID, const osg::Vec3 &currLocalEyePoint) const

void	addImpostorSprite (unsigned int contextID, ImpostorSprite *is)

ImpostorSpriteList &	getImpostorSpriteList (unsigned int contexID)

const ImpostorSpriteList &	getImpostorSpriteList (unsigned int contexID) const

virtual osg::BoundingSphere	computeBound () const

Public Member Functions inherited from osg::LOD
	LOD ()

	LOD (const LOD &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)

	META_Node (osg, LOD)

virtual bool	addChild (Node *child)

virtual bool	addChild (Node *child, float min, float max)

virtual bool	removeChildren (unsigned int pos, unsigned int numChildrenToRemove=1)

void	setCenterMode (CenterMode mode)

CenterMode	getCenterMode () const

void	setCenter (const vec_type &center)

const vec_type &	getCenter () const

void	setRadius (value_type radius)

value_type	getRadius () const

void	setRangeMode (RangeMode mode)

RangeMode	getRangeMode () const

void	setRange (unsigned int childNo, float min, float max)

float	getMinRange (unsigned int childNo) const

float	getMaxRange (unsigned int childNo) const

unsigned int	getNumRanges () const

void	setRangeList (const RangeList &rangeList)

const RangeList &	getRangeList () const

Public Member Functions inherited from osg::Group
	Group ()

	Group (const Group &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)

	META_Node (osg, Group)

virtual Group *	asGroup ()

virtual const Group *	asGroup () const

virtual bool	insertChild (unsigned int index, Node *child)

virtual bool	removeChild (Node *child)

bool	removeChild (unsigned int pos, unsigned int numChildrenToRemove=1)

virtual bool	replaceChild (Node origChild, Node newChild)

virtual unsigned int	getNumChildren () const

virtual bool	setChild (unsigned int i, Node *node)

Node *	getChild (unsigned int i)

const Node *	getChild (unsigned int i) const

bool	containsNode (const Node *node) const

unsigned int	getChildIndex (const Node *node) const

virtual void	setThreadSafeRefUnref (bool threadSafe)

virtual void	resizeGLObjectBuffers (unsigned int maxSize)

virtual void	releaseGLObjects (osg::State *=0) const

Public Member Functions inherited from osg::Node
	Node ()

	Node (const Node &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)

virtual Object *	cloneType () const

virtual Object *	clone (const CopyOp &copyop) const

virtual bool	isSameKindAs (const Object *obj) const

virtual const char *	libraryName () const

virtual const char *	className () const

virtual Node *	asNode ()

virtual const Node *	asNode () const

virtual Drawable *	asDrawable ()

virtual const Drawable *	asDrawable () const

virtual Geometry *	asGeometry ()

virtual const Geometry *	asGeometry () const

virtual Transform *	asTransform ()

virtual const Transform *	asTransform () const

virtual Camera *	asCamera ()

virtual const Camera *	asCamera () const

virtual Switch *	asSwitch ()

virtual const Switch *	asSwitch () const

virtual Geode *	asGeode ()

virtual const Geode *	asGeode () const

virtual osgTerrain::Terrain *	asTerrain ()

virtual const osgTerrain::Terrain *	asTerrain () const

virtual void	accept (NodeVisitor &nv)

virtual void	ascend (NodeVisitor &nv)

const ParentList &	getParents () const

ParentList	getParents ()

Group *	getParent (unsigned int i)

const Group *	getParent (unsigned int i) const

unsigned int	getNumParents () const

NodePathList	getParentalNodePaths (osg::Node *haltTraversalAtNode=0) const

MatrixList	getWorldMatrices (const osg::Node *haltTraversalAtNode=0) const

void	setUpdateCallback (Callback *nc)

Callback *	getUpdateCallback ()

const Callback *	getUpdateCallback () const

void	addUpdateCallback (Callback *nc)

void	removeUpdateCallback (Callback *nc)

unsigned int	getNumChildrenRequiringUpdateTraversal () const

void	setEventCallback (Callback *nc)

Callback *	getEventCallback ()

const Callback *	getEventCallback () const

void	addEventCallback (Callback *nc)

void	removeEventCallback (Callback *nc)

unsigned int	getNumChildrenRequiringEventTraversal () const

void	setCullCallback (Callback *nc)

Callback *	getCullCallback ()

const Callback *	getCullCallback () const

void	addCullCallback (Callback *nc)

void	removeCullCallback (Callback *nc)

void	setCullingActive (bool active)

bool	getCullingActive () const

unsigned int	getNumChildrenWithCullingDisabled () const

bool	isCullingActive () const

unsigned int	getNumChildrenWithOccluderNodes () const

bool	containsOccluderNodes () const

void	setNodeMask (NodeMask nm)

NodeMask	getNodeMask () const

void	setStateSet (osg::StateSet *stateset)

osg::StateSet *	getOrCreateStateSet ()

osg::StateSet *	getStateSet ()

const osg::StateSet *	getStateSet () const

void	setDescriptions (const DescriptionList &descriptions)

DescriptionList &	getDescriptions ()

const DescriptionList &	getDescriptions () const

const std::string &	getDescription (unsigned int i) const

std::string &	getDescription (unsigned int i)

unsigned int	getNumDescriptions () const

void	addDescription (const std::string &desc)

void	setInitialBound (const osg::BoundingSphere &bsphere)

const BoundingSphere &	getInitialBound () const

void	dirtyBound ()

const BoundingSphere &	getBound () const

void	setComputeBoundingSphereCallback (ComputeBoundingSphereCallback *callback)

ComputeBoundingSphereCallback *	getComputeBoundingSphereCallback ()

const ComputeBoundingSphereCallback *	getComputeBoundingSphereCallback () const

Public Member Functions inherited from osg::Object
	Object ()

	Object (bool threadSafeRefUnref)

	Object (const Object &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)

std::string	getCompoundClassName () const

virtual NodeVisitor *	asNodeVisitor ()

virtual const NodeVisitor *	asNodeVisitor () const

virtual StateAttribute *	asStateAttribute ()

virtual const StateAttribute *	asStateAttribute () const

virtual Uniform *	asUniform ()

virtual const Uniform *	asUniform () const

virtual void	setName (const std::string &name)

void	setName (const char *name)

const std::string &	getName () const

void	setDataVariance (DataVariance dv)

DataVariance	getDataVariance () const

virtual void	computeDataVariance ()

void	setUserDataContainer (osg::UserDataContainer *udc)

osg::UserDataContainer *	getUserDataContainer ()

const osg::UserDataContainer *	getUserDataContainer () const

osg::UserDataContainer *	getOrCreateUserDataContainer ()

virtual void	setUserData (Referenced *obj)

virtual Referenced *	getUserData ()

virtual const Referenced *	getUserData () const

template<typename T >
bool	getUserValue (const std::string &name, T &value) const

template<typename T >
void	setUserValue (const std::string &name, const T &value)

template<typename T >
BoolValueObject UCharValueObject UShortValueObject UIntValueObject DoubleValueObject Vec3fValueObject Vec2dValueObject Vec4dValueObject PlaneValueObject MatrixdValueObject BoundingBoxdValueObject BoundingSpheredValueObject bool	getUserValue (const std::string &name, T &value) const

Public Member Functions inherited from osg::Referenced
	Referenced ()

	Referenced (bool threadSafeRefUnref)

	Referenced (const Referenced &)

Referenced &	operator= (const Referenced &)

bool	getThreadSafeRefUnref () const

OpenThreads::Mutex *	getRefMutex () const

int	ref () const

int	unref () const

int	unref_nodelete () const

int	referenceCount () const

ObserverSet *	getObserverSet () const

ObserverSet *	getOrCreateObserverSet () const

void	addObserver (Observer *observer) const

void	removeObserver (Observer *observer) const

Protected Member Functions
virtual	~Impostor ()

ImpostorSprite *	createImpostorSprite (osgUtil::CullVisitor *cv)

Protected Member Functions inherited from osg::LOD
virtual	~LOD ()

Protected Member Functions inherited from osg::Group
virtual	~Group ()

virtual void	childRemoved (unsigned int, unsigned int)

virtual void	childInserted (unsigned int)

Protected Member Functions inherited from osg::Node
virtual	~Node ()

void	addParent (osg::Group *parent)

void	removeParent (osg::Group *parent)

void	setNumChildrenRequiringUpdateTraversal (unsigned int num)

void	setNumChildrenRequiringEventTraversal (unsigned int num)

void	setNumChildrenWithCullingDisabled (unsigned int num)

void	setNumChildrenWithOccluderNodes (unsigned int num)

Protected Member Functions inherited from osg::Object
virtual	~Object ()

Protected Member Functions inherited from osg::Referenced
virtual	~Referenced ()

void	signalObserversAndDelete (bool signalDelete, bool doDelete) const

void	deleteUsingDeleteHandler () const

Protected Attributes
osg::buffered_object < ImpostorSpriteList >	_impostorSpriteListBuffer

float	_impostorThreshold

Protected Attributes inherited from osg::LOD
CenterMode	_centerMode

vec_type	_userDefinedCenter

value_type	_radius

RangeMode	_rangeMode

RangeList	_rangeList

Protected Attributes inherited from osg::Group
NodeList	_children

Protected Attributes inherited from osg::Node
BoundingSphere	_initialBound

ref_ptr < ComputeBoundingSphereCallback >	_computeBoundCallback

BoundingSphere	_boundingSphere

bool	_boundingSphereComputed

ParentList	_parents

ref_ptr< Callback >	_updateCallback

unsigned int	_numChildrenRequiringUpdateTraversal

ref_ptr< Callback >	_eventCallback

unsigned int	_numChildrenRequiringEventTraversal

ref_ptr< Callback >	_cullCallback

bool	_cullingActive

unsigned int	_numChildrenWithCullingDisabled

unsigned int	_numChildrenWithOccluderNodes

NodeMask	_nodeMask

ref_ptr< StateSet >	_stateset

Protected Attributes inherited from osg::Object
std::string	_name

DataVariance	_dataVariance

osg::UserDataContainer *	_userDataContainer

Protected Attributes inherited from osg::Referenced
OpenThreads::AtomicPtr	_observerSet

OpenThreads::Atomic	_refCount

Additional Inherited Members
Static Public Member Functions inherited from osg::Referenced
static OpenThreads::Mutex *	getGlobalReferencedMutex ()

static void	setThreadSafeReferenceCounting (bool enableThreadSafeReferenceCounting)

static bool	getThreadSafeReferenceCounting ()

static void	setDeleteHandler (DeleteHandler *handler)

static DeleteHandler *	getDeleteHandler ()

Detailed Description

Impostor - is a form of Level Of Detail group node which allows both switching between children depending on distance from eye point and image caching.

The principle behind Imposters is that they cache an image of real geometry and then the image is drawn in subsequent frames instead of the real geometry. It's a bit like a Billboard but is updated at runtime and w.r.t view point. By drawing just the texture mapped quad you can cut down scene complexity and improve performance.

For more details have a look at:

http://grail.cs.washington.edu/projects/hic/

The OSG doesn't implement exactly the same technique as above, but its should be a good starting place. The OSG's impostors are much less intrusive since you don't need to restructure your whole scene to use them.

All you need to do to use Impostors is to set up the visible range values for each LOD child of the Impostor, as per osg::LOD, and set an Impostor threshold to tell the renderer at what distance the Impostor's image caching should cut in. The osg::CullVisitor automatically handles all the setting of pre-rendering stages to calculate the required ImpostorSprites (which encapsulates the image cache and quad), and updates them as the view point changes. If you use osg::SceneView/CullVisitor all the complexity of supporting Impostor will be nicely hidden away.

TODO: Various improvements are planned for the Impostor- 1) Estimation of how many frames an ImpostorSprite will be reused, if it won't be used more often than a minimum threshold then do not create ImpostorSprite - use the real geometry. 2) Sharing of texture memory between ImpostorSprites. 3) Simple 3D geometry for ImpostorSprite's rather than Billboarding. 4) Shrinking of the ImpostorSprite size to more closely fit the underlying geometry.

Definition at line 64 of file Impostor.h.

Member Typedef Documentation

typedef std::vector< osg::ref_ptr<ImpostorSprite> > osgSim::Impostor::ImpostorSpriteList

Definition at line 77 of file Impostor.h.

Constructor & Destructor Documentation

osgSim::Impostor::Impostor ( )

osgSim::Impostor::Impostor	(	const Impostor &	es,
		const osg::CopyOp &	copyop = `osg::CopyOp::SHALLOW_COPY`
	)

inline

Definition at line 69 of file Impostor.h.

virtual osgSim::Impostor::~Impostor ( )

inlineprotectedvirtual

Definition at line 109 of file Impostor.h.

Member Function Documentation

void osgSim::Impostor::addImpostorSprite	(	unsigned int	contextID,
		ImpostorSprite *	is
	)

Add an ImpostorSprite to the Impostor.

virtual osg::BoundingSphere osgSim::Impostor::computeBound ( ) const

virtual

Compute the bounding sphere around Node's geometry or children. This method is automatically called by getBound() when the bounding sphere has been marked dirty via dirtyBound().

Reimplemented from osg::LOD.

ImpostorSprite* osgSim::Impostor::createImpostorSprite ( osgUtil::CullVisitor * cv )

protected

ImpostorSprite* osgSim::Impostor::findBestImpostorSprite	(	unsigned int	contextID,
		const osg::Vec3 &	currLocalEyePoint
	)		const

Find the ImposterSprite which fits the current eye point best.

ImpostorSpriteList& osgSim::Impostor::getImpostorSpriteList ( unsigned int contexID )

inline

Get the list of ImpostorSprites attached to this Impostor.

Definition at line 100 of file Impostor.h.

const ImpostorSpriteList& osgSim::Impostor::getImpostorSpriteList ( unsigned int contexID ) const

inline

Get a const list of ImpostorSprites attached to this const Impostor.

Definition at line 103 of file Impostor.h.

float osgSim::Impostor::getImpostorThreshold ( ) const

inline

Definition at line 86 of file Impostor.h.

osgSim::Impostor::META_Node	(	osgSim	,
		Impostor
	)

void osgSim::Impostor::setImpostorThreshold ( float distance )

inline

Set the Impostor threshold distance. For eye points further than this threshold the Imposter is used if appropriate, otherwise the LOD children as chosen as per a standard LOD node.

Definition at line 83 of file Impostor.h.

void osgSim::Impostor::setImpostorThresholdToBound ( float ratio = 1.0f )

inline

Set the Impostor threshold distance relative to the node's bounding sphere's radius.

Definition at line 91 of file Impostor.h.

virtual void osgSim::Impostor::traverse ( osg::NodeVisitor & )

virtual

Traverse downwards : calls children's accept method with NodeVisitor.

Reimplemented from osg::LOD.

Member Data Documentation

osg::buffered_object<ImpostorSpriteList> osgSim::Impostor::_impostorSpriteListBuffer

mutableprotected

Definition at line 111 of file Impostor.h.

float osgSim::Impostor::_impostorThreshold

protected

Definition at line 115 of file Impostor.h.

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

osg_head/include/osgSim/Impostor.h

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation