SoLOD(3)

NAME
SoLOD - The SoLOD class is used to choose a child based distance between viewer and object.

SYNOPSIS

#include <Inventor/nodes/SoLOD.h>

Inherits SoGroup.

  Public Member Functions
virtual SoType getTypeId (void) const
SoLOD (void)
SoLOD (int numchildren)
virtual void doAction (SoAction *action)
virtual void callback (SoCallbackAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void GLRenderBelowPath (SoGLRenderAction *action)
virtual void GLRenderInPath (SoGLRenderAction *action)
virtual void GLRenderOffPath (SoGLRenderAction *action)
virtual void rayPick (SoRayPickAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
virtual void audioRender (SoAudioRenderAction *action)
virtual void notify (SoNotList *nl)
Public Member Functions inherited from SoGroup
SoGroup (void)
SoGroup (int nchildren)
virtual void addChild (SoNode *node)
virtual void insertChild (SoNode *child, int newchildindex)
virtual SoNode * getChild (int index) const
virtual int findChild (const SoNode *node) const
virtual int getNumChildren (void) const
virtual void removeChild (int childindex)
virtual void removeChild (SoNode *child)
virtual void removeAllChildren (void)
virtual void replaceChild (int index, SoNode *newchild)
virtual void replaceChild (SoNode *oldchild, SoNode *newchild)
virtual void getMatrix (SoGetMatrixAction *action)
virtual void handleEvent (SoHandleEventAction *action)
virtual void pick (SoPickAction *action)
virtual void search (SoSearchAction *action)
virtual void write (SoWriteAction *action)
virtual SoChildList * getChildren (void) const
virtual void addWriteReference (SoOutput *out, SbBool isfromfield=FALSE)
Public Member Functions inherited from SoNode
void setOverride (const SbBool state)
SbBool isOverride (void) const
void setNodeType (const NodeType type)
NodeType getNodeType (void) const
virtual SoNode * copy (SbBool copyconnections=FALSE) const
virtual SbBool affectsState (void) const
virtual void grabEventsSetup (void)
virtual void grabEventsCleanup (void)
virtual void startNotify (void)
SbUniqueId getNodeId (void) const
virtual void writeInstance (SoOutput *out)
virtual SoNode * addToCopyDict (void) const
virtual SoFieldContainer * copyThroughConnection (void) const
Public Member Functions inherited from SoFieldContainer
void setToDefaults (void)
SbBool hasDefaultValues (void) const
SbBool fieldsAreEqual (const SoFieldContainer *container) const
void copyFieldValues (const SoFieldContainer *container, SbBool copyconnections=FALSE)
SbBool set (const char *const fielddata)
void get (SbString &fielddata)
virtual int getFields (SoFieldList &l) const
virtual int getAllFields (SoFieldList &l) const
virtual SoField * getField (const SbName &name) const
virtual SoField * getEventIn (const SbName &name) const
virtual SoField * getEventOut (const SbName &name) const
SbBool getFieldName (const SoField *const field, SbName &name) const
SbBool enableNotify (const SbBool flag)
SbBool isNotifyEnabled (void) const
SbBool set (const char *fielddata, SoInput *input)
void get (SbString &fielddata, SoOutput *out)
virtual SbBool validateNewFieldValue (SoField *field, void *newval)
SbBool getIsBuiltIn (void) const
virtual void getFieldsMemorySize (size_t &managed, size_t &unmanaged) const
void setUserData (void *userdata) const
void * getUserData (void) const
Public Member Functions inherited from SoBase
void ref (void) const
void unref (void) const
void unrefNoDelete (void) const
int32_t getRefCount (void) const
void touch (void)
SbBool isOfType (SoType type) const
Returns TRUE if the type of this object is either of the same type or inherited from type.
virtual SbName getName (void) const
virtual void setName (const SbName &newname)
void addAuditor (void *const auditor, const SoNotRec::Type type)
void removeAuditor (void *const auditor, const SoNotRec::Type type)
const SoAuditorList & getAuditors (void) const
SbBool shouldWrite (void)
void assertAlive (void) const

  Static Public Member Functions
static SoType getClassTypeId (void)
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
Static Public Member Functions inherited from SoGroup
static SoType getClassTypeId (void)
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
Static Public Member Functions inherited from SoNode
static uint32_t getCompatibilityTypes (const SoType &nodetype)
static SoType getClassTypeId (void)
static SoNode * getByName (const SbName &name)
static int getByName (const SbName &name, SoNodeList &l)
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
static void initClasses (void)
static SbUniqueId getNextNodeId (void)
static int getActionMethodIndex (const SoType type)
static void getBoundingBoxS (SoAction *action, SoNode *node)
static void GLRenderS (SoAction *action, SoNode *node)
static void callbackS (SoAction *action, SoNode *node)
static void getMatrixS (SoAction *action, SoNode *node)
static void handleEventS (SoAction *action, SoNode *node)
static void pickS (SoAction *action, SoNode *node)
static void rayPickS (SoAction *action, SoNode *node)
static void searchS (SoAction *action, SoNode *node)
static void writeS (SoAction *action, SoNode *node)
static void audioRenderS (SoAction *action, SoNode *node)
static void getPrimitiveCountS (SoAction *action, SoNode *node)
Static Public Member Functions inherited from SoFieldContainer
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
static SoType getClassTypeId (void)
This static method returns the SoType object associated with objects of this class.
static void cleanupClass (void)
static void initCopyDict (void)
static void addCopy (const SoFieldContainer *orig, const SoFieldContainer *copy)
static SoFieldContainer * checkCopy (const SoFieldContainer *orig)
static SoFieldContainer * findCopy (const SoFieldContainer *orig, const SbBool copyconnections)
static void copyDone (void)
Static Public Member Functions inherited from SoBase
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
static SoType getClassTypeId (void)
This static method returns the SoType object associated with objects of this class.
static void addName (SoBase *const base, const char *const name)
static void removeName (SoBase *const base, const char *const name)
static void incrementCurrentWriteCounter (void)
static void decrementCurrentWriteCounter (void)
static SoBase * getNamedBase (const SbName &name, SoType type)
static int getNamedBases (const SbName &name, SoBaseList &baselist, SoType type)
static SbBool read (SoInput *input, SoBase *&base, SoType expectedtype)
static void setInstancePrefix (const SbString &c)
static void setTraceRefs (SbBool trace)
static SbBool getTraceRefs (void)
static SbBool connectRoute (SoInput *input, const SbName &fromnodename, const SbName &fromfieldname, const SbName &tonodename, const SbName &tofieldname)
static SbBool readRoute (SoInput *input)

  Public Attributes
SoMFFloat range
SoSFVec3f center
Public Attributes inherited from SoBase

  Protected Member Functions
virtual const SoFieldData * getFieldData (void) const
virtual ~SoLOD ()
virtual int whichToTraverse (SoAction *)
Protected Member Functions inherited from SoGroup
virtual ~SoGroup ()
virtual SbBool readInstance (SoInput *in, unsigned short flags)
virtual SbBool readChildren (SoInput *in)
virtual void copyContents (const SoFieldContainer *from, SbBool copyconnections)
virtual SoNotRec createNotRec (void)
void setOperation (const SoNotRec::OperationType opType=SoNotRec::UNSPECIFIED, const SoNode *cc=NULL, const SoNode *pc=NULL, const int ci=-1)
Protected Member Functions inherited from SoNode
SoNode (void)
virtual ~SoNode ()
Protected Member Functions inherited from SoFieldContainer
SoFieldContainer (void)
virtual ~SoFieldContainer ()
Protected Member Functions inherited from SoBase
SoBase (void)
virtual ~SoBase ()
virtual void destroy (void)
SbBool hasMultipleWriteRefs (void) const
SbBool writeHeader (SoOutput *out, SbBool isgroup, SbBool isengine) const
void writeFooter (SoOutput *out) const
virtual const char * getFileFormatName (void) const

  Static Protected Member Functions
static const SoFieldData ** getFieldDataPtr (void)
Static Protected Member Functions inherited from SoGroup
static const SoFieldData ** getFieldDataPtr (void)
Static Protected Member Functions inherited from SoNode
static const SoFieldData ** getFieldDataPtr (void)
static void setNextActionMethodIndex (int index)
static int getNextActionMethodIndex (void)
static void incNextActionMethodIndex (void)
static void setCompatibilityTypes (const SoType &nodetype, const uint32_t bitmask)
Static Protected Member Functions inherited from SoBase
static uint32_t getCurrentWriteCounter (void)
static void staticDataLock (void)
static void staticDataUnlock (void)

  Additional Inherited Members
Public Types inherited from SoNode
enum NodeType { INVENTOR = 0x0000, VRML1 = 0x0001, VRML2 = 0x0002, INVENTOR_1 = 0x0004, INVENTOR_2_0 = 0x0008, INVENTOR_2_1 = 0x0010, INVENTOR_2_5 = 0x0020, INVENTOR_2_6 = 0x0040, COIN_1_0 = 0x0080, COIN_2_0 = 0x0100, EXTENSION = 0x0200, COIN_2_2 = 0x0400, COIN_2_3 = 0x0800, COIN_2_4 = 0x1000, INVENTOR_5_0 = 0x2000, COIN_2_5 = 0x4000, COIN_3_0 = 0x8000, INVENTOR_6_0 = 0x10000, COIN_4_0 = 0x20000 }
Protected Types inherited from SoBase
enum BaseFlags { IS_ENGINE = 0x01, IS_GROUP = 0x02 }
Protected Attributes inherited from SoGroup
SoChildList * children
Protected Attributes inherited from SoNode
SbUniqueId uniqueId
Protected Attributes inherited from SoFieldContainer
SbBool isBuiltIn
Static Protected Attributes inherited from SoNode
static SbUniqueId nextUniqueId = 1
static int nextActionMethodIndex = 0

Detailed Description

The SoLOD class is used to choose a child based distance between viewer and object. The class documentation for the SoLOD node class would be similar enough to that of SoLevelOfDetail that we will refer you to look at that one first. It will explain the general principles of what a level-of-detail mechanism is, and why and how to use it.

(The main difference between SoLOD and SoLevelOfDetail is that SoLOD uses the faster 'distance-to-viewer' technique for implementing level-of-detail functionality, versus the more correct (but potentially slower) 'projected-bbox-area' technique used by SoLevelOfDetail.)

Here's a mockup example (in Inventor file format style, but easily converted to code) that shows how to use this node:

LOD {
   range [ 10, 20, 30, 40 ]
   Sphere { }
   Cylinder { }
   Cone { }
   Cube { }
   Info { }
}

For the sub-scene graph above, when the LOD-object is less than 10 units away from the viewpoint camera, an SoSphere will be shown. For distances 10 - 20 units away, this will be changed to the SoCylinder, and so on. For distances of more than 40 units from the camera, an SoInfo node will be traversed / rendered -- i.e., nothing will be shown. (This is a common 'trick' used to optimize rendering when models get far enough away from the camera that we want to remove them completely).

Note that when using an SoOrthographicCamera in the examiner viewers of the SoQt, SoWin and SoXt libraries, it will seem like the SoLOD node is not working when using the 'Zoom' functionality. What happens is that an SoOrthographicCamera is not actually moved, the 'zoom' effect is accomplished simply by changing its height-of-view setting (i.e. the value of the SoOrthographicCamera::height field), but its position remains constant. So the distance to the camera will not change, which means SoLOD will pick the same child, no matter how much one 'zooms'.

(The SoLevelOfDetail node uses the screen space area of the object to decide when to switch children, so that node will still work with SoOrthographicCamera.)

FILE FORMAT/DEFAULTS:

LOD {
    center 0 0 0
    range [  ]
}

Since
    SGI Inventor 2.1

See also
    SoLevelOfDetail

Constructor & Destructor Documentation

  SoLOD::SoLOD (void )
Default constructor.

  SoLOD::SoLOD (int numchildren)
Constructor.

The argument should be the approximate number of children which is expected to be inserted below this node. The number need not be exact, as it is only used as a hint for better memory resource allocation.

  SoLOD::~SoLOD () [protected], [virtual]
Destructor.

Member Function Documentation

  SoType SoLOD::getClassTypeId (void ) [static]
This static method returns the SoType object associated with objects of this class.

  SoType SoLOD::getTypeId (void ) const [virtual]
Returns the type identification of an object derived from a class inheriting SoBase. This is used for runtime type checking and 'downward' casting.

Reimplemented from SoGroup.

  const SoFieldData ** SoLOD::getFieldDataPtr (void ) [static], [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.
 Returns the SoFieldData class which holds information about fields in this node.

  const SoFieldData * SoLOD::getFieldData (void ) const [protected], [virtual]
Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoGroup.

  void SoLOD::doAction (SoAction * action) [virtual]
This function performs the typical operation of a node for any action.

Reimplemented from SoGroup.

  void SoLOD::callback (SoCallbackAction * action) [virtual]
Action method for SoCallbackAction.

Simply updates the state according to how the node behaves for the render action, so the application programmer can use the SoCallbackAction for extracting information about the scene graph.

Reimplemented from SoGroup.

  void SoLOD::GLRender (SoGLRenderAction * action) [virtual]
Action method for the SoGLRenderAction.

This is called during rendering traversals. Nodes influencing the rendering state in any way or want to throw geometry primitives at OpenGL override this method.

Reimplemented from SoGroup.

  void SoLOD::GLRenderBelowPath (SoGLRenderAction * action) [virtual]
Implements the SoAction::BELOW_PATH traversal method for the rendering action.

Reimplemented from SoNode.

  void SoLOD::GLRenderInPath (SoGLRenderAction * action) [virtual]
Implements the SoAction::IN_PATH traversal method for the rendering action.

Reimplemented from SoNode.

  void SoLOD::GLRenderOffPath (SoGLRenderAction * action) [virtual]
Implements the SoAction::OFF_PATH traversal method for the rendering action.

Reimplemented from SoNode.

  void SoLOD::rayPick (SoRayPickAction * action) [virtual]
Action method for SoRayPickAction.

Checks the ray specification of the action and tests for intersection with the data of the node.

Nodes influencing relevant state variables for how picking is done also override this method.

Reimplemented from SoNode.

  void SoLOD::getBoundingBox (SoGetBoundingBoxAction * action) [virtual]
Action method for the SoGetBoundingBoxAction.

Calculates bounding box and center coordinates for node and modifies the values of the action to encompass the bounding box for this node and to shift the center point for the scene more towards the one for this node.

Nodes influencing how geometry nodes calculate their bounding box also override this method to change the relevant state variables.

Reimplemented from SoGroup.

  void SoLOD::getPrimitiveCount (SoGetPrimitiveCountAction * action) [virtual]
Action method for the SoGetPrimitiveCountAction.

Calculates the number of triangle, line segment and point primitives for the node and adds these to the counters of the action.

Nodes influencing how geometry nodes calculate their primitive count also override this method to change the relevant state variables.

Reimplemented from SoGroup.

  void SoLOD::audioRender (SoAudioRenderAction * action) [virtual]
Action method for SoAudioRenderAction.

Does common processing for SoAudioRenderAction action instances.

Reimplemented from SoGroup.

  void SoLOD::notify (SoNotList * l) [virtual]
Notifies all auditors for this instance when changes are made.

Reimplemented from SoNode.

  int SoLOD::whichToTraverse (SoAction * action) [protected], [virtual]
Returns the child to traverse based on the ranges in SoLOD::range. Will clamp to index to the number of children. This method will return -1 if no child should be traversed. This will only happen if the node has no children though.

Member Data Documentation

  SoMFFloat SoLOD::range
The distance ranges which decides when to use each child for traversal / rendering. See usage example in main class documentation of SoLOD for an explanation of how this vector should be set up correctly.

By default this vector just contains a single value 0.0f.

  SoSFVec3f SoLOD::center
This vector represents an offset within the object from the geometric center point to the center point the application programmer would actually like the distance between the viewer and the object to be calculated from.

Default value is [0, 0, 0]. It is usually not necessary to change this field.

Author

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