OpenSceneGraph  3.0.1
Public Types | Public Member Functions | Protected Member Functions | Protected Attributes | List of all members
osgSim::Impostor Class Reference

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. More...

Inheritance diagram for osgSim::Impostor:
Inheritance graph
[legend]

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 }
 Modes which control how the center of object should be determined when computing which child is active. More...
 
enum  RangeMode { DISTANCE_FROM_EYE_POINT, PIXEL_SIZE_ON_SCREEN }
 Modes that control how the range values should be interpreted when computing which child is active. More...
 
typedef
osg::BoundingSphere::vec_type 
vec_type
 
typedef
osg::BoundingSphere::value_type 
value_type
 
typedef std::pair< float, float > MinMaxPair
 
typedef std::vector< MinMaxPairRangeList
 

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)
 Traverse downwards : calls children's accept method with NodeVisitor. More...
 
void setImpostorThreshold (float distance)
 Set the Impostor threshold distance. More...
 
float getImpostorThreshold () const
 
void setImpostorThresholdToBound (float ratio=1.0f)
 Set the Impostor threshold distance relative to the node's bounding sphere's radius. More...
 
ImpostorSpritefindBestImpostorSprite (unsigned int contextID, const osg::Vec3 &currLocalEyePoint) const
 Find the ImposterSprite which fits the current eye point best. More...
 
void addImpostorSprite (unsigned int contextID, ImpostorSprite *is)
 Add an ImpostorSprite to the Impostor. More...
 
ImpostorSpriteListgetImpostorSpriteList (unsigned int contexID)
 Get the list of ImpostorSprites attached to this Impostor. More...
 
const ImpostorSpriteListgetImpostorSpriteList (unsigned int contexID) const
 Get a const list of ImpostorSprites attached to this const Impostor. More...
 
virtual osg::BoundingSphere computeBound () const
 Compute the bounding sphere around Node's geometry or children. More...
 
- Public Member Functions inherited from osg::LOD
 LOD ()
 
 LOD (const LOD &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)
 Copy constructor using CopyOp to manage deep vs shallow copy. More...
 
 META_Node (osg, LOD)
 
virtual bool addChild (Node *child)
 Add Node to Group. More...
 
virtual bool addChild (Node *child, float min, float max)
 
virtual bool removeChildren (unsigned int pos, unsigned int numChildrenToRemove=1)
 Remove children from Group. More...
 
void setCenterMode (CenterMode mode)
 Set how the center of object should be determined when computing which child is active. More...
 
CenterMode getCenterMode () const
 Get how the center of object should be determined when computing which child is active. More...
 
void setCenter (const vec_type &center)
 Sets the object-space point which defines the center of the osg::LOD. More...
 
const vec_typegetCenter () const
 return the LOD center point. More...
 
void setRadius (value_type radius)
 Set the object-space reference radius of the volume enclosed by the LOD. More...
 
value_type getRadius () const
 Get the object-space radius of the volume enclosed by the LOD. More...
 
void setRangeMode (RangeMode mode)
 Set how the range values should be interpreted when computing which child is active. More...
 
RangeMode getRangeMode () const
 Get how the range values should be interpreted when computing which child is active. More...
 
void setRange (unsigned int childNo, float min, float max)
 Sets the min and max visible ranges of range of specific child. More...
 
float getMinRange (unsigned int childNo) const
 returns the min visible range for specified child. More...
 
float getMaxRange (unsigned int childNo) const
 returns the max visible range for specified child. More...
 
unsigned int getNumRanges () const
 returns the number of ranges currently set. More...
 
void setRangeList (const RangeList &rangeList)
 set the list of MinMax ranges for each child. More...
 
const RangeListgetRangeList () const
 return the list of MinMax ranges for each child. More...
 
- Public Member Functions inherited from osg::Group
 Group ()
 
 Group (const Group &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)
 Copy constructor using CopyOp to manage deep vs shallow copy. More...
 
 META_Node (osg, Group)
 
virtual GroupasGroup ()
 convert 'this' into a Group pointer if Node is a Group, otherwise return 0. More...
 
virtual const GroupasGroup () const
 convert 'const this' into a const Group pointer if Node is a Group, otherwise return 0. More...
 
virtual bool insertChild (unsigned int index, Node *child)
 Insert Node to Group at specific location. More...
 
bool removeChild (Node *child)
 Remove Node from Group. More...
 
bool removeChild (unsigned int pos, unsigned int numChildrenToRemove=1)
 Remove Node from Group. More...
 
virtual bool replaceChild (Node *origChild, Node *newChild)
 Replace specified Node with another Node. More...
 
unsigned int getNumChildren () const
 Return the number of children nodes. More...
 
virtual bool setChild (unsigned int i, Node *node)
 Set child node at position i. More...
 
NodegetChild (unsigned int i)
 Return child node at position i. More...
 
const NodegetChild (unsigned int i) const
 Return child node at position i. More...
 
bool containsNode (const Node *node) const
 Return true if node is contained within Group. More...
 
unsigned int getChildIndex (const Node *node) const
 Get the index number of child, return a value between 0 and _children.size()-1 if found, if not found then return _children.size(). More...
 
virtual void setThreadSafeRefUnref (bool threadSafe)
 Set whether to use a mutex to ensure ref() and unref() are thread safe. More...
 
virtual void resizeGLObjectBuffers (unsigned int maxSize)
 Resize any per context GLObject buffers to specified size. More...
 
virtual void releaseGLObjects (osg::State *=0) const
 If State is non-zero, this function releases any associated OpenGL objects for the specified graphics context. More...
 
- Public Member Functions inherited from osg::Node
 Node ()
 Construct a node. More...
 
 Node (const Node &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)
 Copy constructor using CopyOp to manage deep vs shallow copy. More...
 
virtual ObjectcloneType () const
 clone an object of the same type as the node. More...
 
virtual Objectclone (const CopyOp &copyop) const
 return a clone of a node, with Object* return type. More...
 
virtual bool isSameKindAs (const Object *obj) const
 return true if this and obj are of the same kind of object. More...
 
virtual const char * libraryName () const
 return the name of the node's library. More...
 
virtual const char * className () const
 return the name of the node's class type. More...
 
virtual TransformasTransform ()
 Convert 'this' into a Transform pointer if Node is a Transform, otherwise return 0. More...
 
virtual const TransformasTransform () const
 convert 'const this' into a const Transform pointer if Node is a Transform, otherwise return 0. More...
 
virtual SwitchasSwitch ()
 Convert 'this' into a Switch pointer if Node is a Switch, otherwise return 0. More...
 
virtual const SwitchasSwitch () const
 convert 'const this' into a const Switch pointer if Node is a Switch, otherwise return 0. More...
 
virtual GeodeasGeode ()
 Convert 'this' into a Geode pointer if Node is a Geode, otherwise return 0. More...
 
virtual const GeodeasGeode () const
 convert 'const this' into a const Geode pointer if Node is a Geode, otherwise return 0. More...
 
virtual osgTerrain::TerrainasTerrain ()
 Convert 'this' into a Transform pointer if Node is a Terrain, otherwise return 0. More...
 
virtual const osgTerrain::TerrainasTerrain () const
 convert 'const this' into a const Terrain pointer if Node is a Terrain, otherwise return 0. More...
 
virtual void accept (NodeVisitor &nv)
 Visitor Pattern : calls the apply method of a NodeVisitor with this node's type. More...
 
virtual void ascend (NodeVisitor &nv)
 Traverse upwards : calls parents' accept method with NodeVisitor. More...
 
const ParentListgetParents () const
 Get the parent list of node. More...
 
ParentList getParents ()
 Get the a copy of parent list of node. More...
 
GroupgetParent (unsigned int i)
 
const GroupgetParent (unsigned int i) const
 Get a single const parent of node. More...
 
unsigned int getNumParents () const
 Get the number of parents of node. More...
 
NodePathList getParentalNodePaths (osg::Node *haltTraversalAtNode=0) const
 Get the list of node paths parent paths. More...
 
MatrixList getWorldMatrices (const osg::Node *haltTraversalAtNode=0) const
 Get the list of matrices that transform this node from local coordinates to world coordinates. More...
 
void setUpdateCallback (NodeCallback *nc)
 Set update node callback, called during update traversal. More...
 
NodeCallbackgetUpdateCallback ()
 Get update node callback, called during update traversal. More...
 
const NodeCallbackgetUpdateCallback () const
 Get const update node callback, called during update traversal. More...
 
void addUpdateCallback (NodeCallback *nc)
 Convenience method that sets the update callback of the node if it doesn't exist, or nest it into the existing one. More...
 
void removeUpdateCallback (NodeCallback *nc)
 Convenience method that removes a given callback from a node, even if that callback is nested. More...
 
unsigned int getNumChildrenRequiringUpdateTraversal () const
 Get the number of Children of this node which require Update traversal, since they have an Update Callback attached to them or their children. More...
 
void setEventCallback (NodeCallback *nc)
 Set event node callback, called during event traversal. More...
 
NodeCallbackgetEventCallback ()
 Get event node callback, called during event traversal. More...
 
const NodeCallbackgetEventCallback () const
 Get const event node callback, called during event traversal. More...
 
void addEventCallback (NodeCallback *nc)
 Convenience method that sets the event callback of the node if it doesn't exist, or nest it into the existing one. More...
 
void removeEventCallback (NodeCallback *nc)
 Convenience method that removes a given callback from a node, even if that callback is nested. More...
 
unsigned int getNumChildrenRequiringEventTraversal () const
 Get the number of Children of this node which require Event traversal, since they have an Event Callback attached to them or their children. More...
 
void setCullCallback (NodeCallback *nc)
 Set cull node callback, called during cull traversal. More...
 
NodeCallbackgetCullCallback ()
 Get cull node callback, called during cull traversal. More...
 
const NodeCallbackgetCullCallback () const
 Get const cull node callback, called during cull traversal. More...
 
void addCullCallback (NodeCallback *nc)
 Convenience method that sets the cull callback of the node if it doesn't exist, or nest it into the existing one. More...
 
void removeCullCallback (NodeCallback *nc)
 Convenience method that removes a given callback from a node, even if that callback is nested. More...
 
void setCullingActive (bool active)
 Set the view frustum/small feature culling of this node to be active or inactive. More...
 
bool getCullingActive () const
 Get the view frustum/small feature _cullingActive flag for this node. More...
 
unsigned int getNumChildrenWithCullingDisabled () const
 Get the number of Children of this node which have culling disabled. More...
 
bool isCullingActive () const
 Return true if this node can be culled by view frustum, occlusion or small feature culling during the cull traversal. More...
 
unsigned int getNumChildrenWithOccluderNodes () const
 Get the number of Children of this node which are or have OccluderNode's. More...
 
bool containsOccluderNodes () const
 return true if this node is an OccluderNode or the subgraph below this node are OccluderNodes. More...
 
void setNodeMask (NodeMask nm)
 Set the node mask. More...
 
NodeMask getNodeMask () const
 Get the node Mask. More...
 
void setStateSet (osg::StateSet *stateset)
 Set the node's StateSet. More...
 
osg::StateSetgetOrCreateStateSet ()
 return the node's StateSet, if one does not already exist create it set the node and return the newly created StateSet. More...
 
osg::StateSetgetStateSet ()
 Return the node's StateSet. More...
 
const osg::StateSetgetStateSet () const
 Return the node's const StateSet. More...
 
void setDescriptions (const DescriptionList &descriptions)
 Set the list of string descriptions. More...
 
DescriptionListgetDescriptions ()
 Get the description list of the node. More...
 
const DescriptionListgetDescriptions () const
 Get the const description list of the const node. More...
 
const std::string & getDescription (unsigned int i) const
 Get a single const description of the const node. More...
 
std::string & getDescription (unsigned int i)
 Get a single description of the node. More...
 
unsigned int getNumDescriptions () const
 Get the number of descriptions of the node. More...
 
void addDescription (const std::string &desc)
 Add a description string to the node. More...
 
void setInitialBound (const osg::BoundingSphere &bsphere)
 Set the initial bounding volume to use when computing the overall bounding volume. More...
 
const BoundingSpheregetInitialBound () const
 Set the initial bounding volume to use when computing the overall bounding volume. More...
 
void dirtyBound ()
 Mark this node's bounding sphere dirty. More...
 
const BoundingSpheregetBound () const
 Get the bounding sphere of node. More...
 
void setComputeBoundingSphereCallback (ComputeBoundingSphereCallback *callback)
 Set the compute bound callback to override the default computeBound. More...
 
ComputeBoundingSphereCallbackgetComputeBoundingSphereCallback ()
 Get the compute bound callback. More...
 
const
ComputeBoundingSphereCallback
getComputeBoundingSphereCallback () const
 Get the const compute bound callback. More...
 
- Public Member Functions inherited from osg::Object
 Object ()
 Construct an object. More...
 
 Object (bool threadSafeRefUnref)
 
 Object (const Object &, const CopyOp &copyop=CopyOp::SHALLOW_COPY)
 Copy constructor, optional CopyOp object can be used to control shallow vs deep copying of dynamic data. More...
 
virtual void setName (const std::string &name)
 Set the name of object using C++ style string. More...
 
void setName (const char *name)
 Set the name of object using a C style string. More...
 
const std::string & getName () const
 Get the name of object. More...
 
void setDataVariance (DataVariance dv)
 Set the data variance of this object. More...
 
DataVariance getDataVariance () const
 Get the data variance of this object. More...
 
virtual void computeDataVariance ()
 Compute the DataVariance based on an assessment of callback etc. More...
 
void setUserDataContainer (osg::UserDataContainer *udc)
 set the UserDataContainer object. More...
 
osg::UserDataContainergetUserDataContainer ()
 get the UserDataContainer attached to this object. More...
 
const osg::UserDataContainergetUserDataContainer () const
 get the const UserDataContainer attached to this object. More...
 
osg::UserDataContainergetOrCreateUserDataContainer ()
 Convinience method that returns the UserDataContainer, and if one doesn't already exist creates and assigns a DefaultUserDataContainer to the Object and then return this new UserDataContainer. More...
 
virtual void setUserData (Referenced *obj)
 Set user data, data must be subclassed from Referenced to allow automatic memory handling. More...
 
virtual ReferencedgetUserData ()
 Get user data. More...
 
virtual const ReferencedgetUserData () const
 Get const user data. More...
 
template<typename T >
bool getUserValue (const std::string &name, T &value) const
 Convinience method that casts the named UserObject to osg::TemplateValueObject<T> and gets the value. More...
 
template<typename T >
void setUserValue (const std::string &name, const T &value)
 Convinience method that creates the osg::TemplateValueObject<T> to store the specified value and adds it as a named UserObject. More...
 
template<typename T >
BoolValueObject
UCharValueObject
UShortValueObject
UIntValueObject
DoubleValueObject
Vec3fValueObject
Vec2dValueObject
Vec4dValueObject
PlaneValueObject
MatrixdValueObject bool 
getUserValue (const std::string &name, T &value) const
 provide implementation of osg::Object::getUserValue(..) template More...
 
- Public Member Functions inherited from osg::Referenced
 Referenced ()
 
 Referenced (bool threadSafeRefUnref)
 
 Referenced (const Referenced &)
 
Referencedoperator= (const Referenced &)
 
bool getThreadSafeRefUnref () const
 Get whether a mutex is used to ensure ref() and unref() are thread safe. More...
 
OpenThreads::Mutex * getRefMutex () const
 Get the mutex used to ensure thread safety of ref()/unref(). More...
 
int ref () const
 Increment the reference count by one, indicating that this object has another pointer which is referencing it. More...
 
int unref () const
 Decrement the reference count by one, indicating that a pointer to this object is referencing it. More...
 
int unref_nodelete () const
 Decrement the reference count by one, indicating that a pointer to this object is referencing it. More...
 
int referenceCount () const
 Return the number of pointers currently referencing this object. More...
 
ObserverSetgetObserverSet () const
 Get the ObserverSet if one is attached, otherwise return NULL. More...
 
ObserverSetgetOrCreateObserverSet () const
 Get the ObserverSet if one is attached, otherwise create an ObserverSet, attach it, then return this newly created ObserverSet. More...
 
void addObserver (Observer *observer) const
 Add a Observer that is observing this object, notify the Observer when this object gets deleted. More...
 
void removeObserver (Observer *observer) const
 Remove Observer that is observing this object. More...
 

Protected Member Functions

virtual ~Impostor ()
 
ImpostorSpritecreateImpostorSprite (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 ()
 Node destructor. More...
 
void addParent (osg::Group *node)
 
void removeParent (osg::Group *node)
 
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 ()
 Object destructor. More...
 
- 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< NodeCallback_updateCallback
 
unsigned int _numChildrenRequiringUpdateTraversal
 
ref_ptr< NodeCallback_eventCallback
 
unsigned int _numChildrenRequiringEventTraversal
 
ref_ptr< NodeCallback_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 ()
 Get the optional global Referenced mutex, this can be shared between all osg::Referenced. More...
 
static void setThreadSafeReferenceCounting (bool enableThreadSafeReferenceCounting)
 Set whether reference counting should use a mutex for thread safe reference counting. More...
 
static bool getThreadSafeReferenceCounting ()
 Get whether reference counting is active. More...
 
static void setDeleteHandler (DeleteHandler *handler)
 Set a DeleteHandler to which deletion of all referenced counted objects will be delegated. More...
 
static DeleteHandlergetDeleteHandler ()
 Get a DeleteHandler. More...
 

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.

Member Typedef Documentation

Constructor & Destructor Documentation

osgSim::Impostor::Impostor ( )
osgSim::Impostor::Impostor ( const Impostor es,
const osg::CopyOp copyop = osg::CopyOp::SHALLOW_COPY 
)
inline
virtual osgSim::Impostor::~Impostor ( )
inlineprotectedvirtual

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.

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

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

float osgSim::Impostor::getImpostorThreshold ( ) const
inline
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.

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

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

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
float osgSim::Impostor::_impostorThreshold
protected

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

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Generated at Fri Mar 1 2013 18:59:50 for the OpenSceneGraph by doxygen 1.8.3.1.