SoLevelOfDetail(3)

📦
version 4.0.10 · 4 versions
, in fedora 43, fedora 44

💖 SoLevelOfDetail(3) — a Coin era icon 💖

okay bestie, gather round 🫶 this is the manual page for SoLevelOfDetail, straight out of Coin, sitting pretty in section 3 of the manual. It's a whole class, and yes she's serving, we'll get into all of it. ✨

✨ NAME ✨

SoLevelOfDetail — the SoLevelOfDetail class is used to choose a child based on projected size. 💅

Like. She looks at how big things are gonna look on screen and picks accordingly. That's the whole vibe of her. 🦋

no cap, that's genuinely the entire NAME section — but bestie, this is only part 1 of 3, so do not go anywhere, there's so much more coming 🌸

✨ SYNOPSIS ✨

#include <Inventor/nodes/SoLevelOfDetail.h>

Inherits SoGroup.

💅 Public Member Functions 💅

  • virtual SoType getTypeId (void) const — bestie, this is literally how you ask the node what type it is 💅
  • SoLevelOfDetail (void) — the no-arg constructor, periodt
  • SoLevelOfDetail (int numchildren) — constructor that takes numchildren, slay
  • virtual void doAction (SoAction *action) — does the SoAction thing, iconic
  • virtual void callback (SoCallbackAction *action) — handles SoCallbackAction, no cap
  • virtual void GLRender (SoGLRenderAction *action) — GL render time with SoGLRenderAction ✨
  • virtual void rayPick (SoRayPickAction *action) — ray pick vibes with SoRayPickAction 🔥
  • virtual void getBoundingBox (SoGetBoundingBoxAction *action) — gets the bounding box via SoGetBoundingBoxAction 📦
  • virtual void audioRender (SoAudioRenderAction *action) — audio render with SoAudioRenderAction 🎧
  • virtual void notify (SoNotList *nl) — notify with SoNotList, bestie

🦋 Public Member Functions inherited from SoGroup 🦋

  • SoGroup (void) — no-arg constructor, inherited
  • SoGroup (int nchildren) — constructor with nchildren, inherited
  • virtual void addChild (SoNode *node) — adds a child node, so iconic
  • virtual void insertChild (SoNode *child, int newchildindex) — inserts child at newchildindex 💖
  • virtual SoNode * getChild (int index) const — gets child at index 🎀
  • virtual int findChild (const SoNode *node) const — finds node in the child list 🔍
  • virtual int getNumChildren (void) const — how many children? bestie needs to know
  • virtual void removeChild (int childindex) — removes child by childindex 💀
  • virtual void removeChild (SoNode *child) — removes child node, bye
  • virtual void removeAllChildren (void) — removes every single child, periodt
  • virtual void replaceChild (int index, SoNode *newchild) — replaces child at index with newchild ✨
  • virtual void replaceChild (SoNode *oldchild, SoNode *newchild) — replaces oldchild with newchild 🌈
  • virtual void getMatrix (SoGetMatrixAction *action) — matrix time with SoGetMatrixAction
  • virtual void handleEvent (SoHandleEventAction *action) — handles SoHandleEventAction
  • virtual void pick (SoPickAction *action) — pick with SoPickAction
  • virtual void search (SoSearchAction *action) — search with SoSearchAction
  • virtual void write (SoWriteAction *action) — write with SoWriteAction
  • virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action) — counts primitives with SoGetPrimitiveCountAction
  • virtual SoChildList * getChildren (void) const — gets the SoChildList pointer
  • virtual void addWriteReference (SoOutput *out, SbBool isfromfield=FALSE) — adds write reference, isfromfield defaults to FALSE

🌸 Public Member Functions inherited from SoNode 🌸

  • void setOverride (const SbBool state) — sets override state
  • SbBool isOverride (void) const — is it override? returns SbBool
  • void setNodeType (const NodeType type) — sets node type to type
  • NodeType getNodeType (void) const — gets the NodeType
  • virtual SoNode * copy (SbBool copyconnections=FALSE) const — copy, copyconnections defaults to FALSE
  • virtual SbBool affectsState (void) const — does it affect state? returns SbBool
  • virtual void GLRenderBelowPath (SoGLRenderAction *action) — GL render below path
  • virtual void GLRenderInPath (SoGLRenderAction *action) — GL render in path
  • virtual void GLRenderOffPath (SoGLRenderAction *action) — GL render off path
  • virtual void grabEventsSetup (void) — grab events setup
  • virtual void grabEventsCleanup (void) — grab events cleanup
  • virtual void startNotify (void) — start notify
  • SbUniqueId getNodeId (void) const — gets the unique node id
  • virtual void writeInstance (SoOutput *out) — write instance
  • virtual SoNode * addToCopyDict (void) const — adds to copy dict
  • virtual SoFieldContainer * copyThroughConnection (void) const — copy through connection

💜 Public Member Functions inherited from SoFieldContainer 💜

  • void setToDefaults (void) — sets everything to defaults
  • SbBool hasDefaultValues (void) const — has default values? returns SbBool
  • SbBool fieldsAreEqual (const SoFieldContainer *container) const — checks if fields are equal to container
  • void copyFieldValues (const SoFieldContainer *container, SbBool copyconnections=FALSE) — copies field values from container, copyconnections defaults to FALSE
  • SbBool set (const char *const fielddata) — sets from fielddata string
  • void get (SbString &fielddata) — gets into fielddata
  • virtual int getFields (SoFieldList &l) const — gets fields into list l
  • virtual int getAllFields (SoFieldList &l) const — gets all fields into list l
  • virtual SoField * getField (const SbName &name) const — gets field by name
  • virtual SoField * getEventIn (const SbName &name) const — gets event in by name
  • virtual SoField * getEventOut (const SbName &name) const — gets event out by name
  • SbBool getFieldName (const SoField *const field, SbName &name) const — gets field name for field
  • SbBool enableNotify (const SbBool flag) — enables notify with flag
  • SbBool isNotifyEnabled (void) const — is notify enabled? returns SbBool
  • SbBool set (const char *fielddata, SoInput *input) — sets from fielddata with input
  • void get (SbString &fielddata, SoOutput *out) — gets into fielddata with out
  • virtual SbBool validateNewFieldValue (SoField *field, void *newval) — validates new field value for field
  • SbBool getIsBuiltIn (void) const — is it built in? returns SbBool
  • virtual void getFieldsMemorySize (size_t &managed, size_t &unmanaged) const — gets fields memory size into managed and unmanaged
  • void setUserData (void *userdata) const — sets user data
  • void * getUserData (void) const — gets user data pointer

🌈 Public Member Functions inherited from SoBase 🌈

  • void ref (void) const — ref it up
  • void unref (void) const — unref it
  • void unrefNoDelete (void) const — unref without delete
  • int32_t getRefCount (void) const — gets ref count as int32_t
  • void touch (void) — touch it
  • 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 — gets name as SbName
  • virtual void setName (const SbName &newname) — sets name to newname
  • void addAuditor (void *const auditor, const SoNotRec::Type type) — adds auditor with type
  • void removeAuditor (void *const auditor, const SoNotRec::Type type) — removes auditor with type
  • const SoAuditorList & getAuditors (void) const — gets auditors as SoAuditorList reference
  • SbBool shouldWrite (void) — should it write? returns SbBool
  • void assertAlive (void) const — asserts alive, bestie

⭐ Static Public Member Functions ⭐

  • static SoType getClassTypeId (void) — gets the class type id
  • 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) — gets the class type id, inherited
  • 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) — gets compatibility types for nodetype
  • static SoType getClassTypeId (void) — gets class type id
  • static SoNode * getByName (const SbName &name) — gets node by name
  • static int getByName (const SbName &name, SoNodeList &l) — gets nodes by name into list 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) — init all the classes, periodt
  • static SbUniqueId getNextNodeId (void) — gets next unique node id
  • static int getActionMethodIndex (const SoType type) — gets action method index for type
  • static void getBoundingBoxS (SoAction *action, SoNode *node) — static bounding box
  • static void GLRenderS (SoAction *action, SoNode *node) — static GL render
  • static void callbackS (SoAction *action, SoNode *node) — static callback
  • static void getMatrixS (SoAction *action, SoNode *node) — static get matrix
  • static void handleEventS (SoAction *action, SoNode *node) — static handle event
  • static void pickS (SoAction *action, SoNode *node) — static pick
  • static void rayPickS (SoAction *action, SoNode *node) — static ray pick
  • static void searchS (SoAction *action, SoNode *node) — static search
  • static void writeS (SoAction *action, SoNode *node) — static write
  • static void audioRenderS (SoAction *action, SoNode *node) — static audio render
  • static void getPrimitiveCountS (SoAction *action, SoNode *node) — static get primitive count

⭐ 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) — cleanup class
  • static void initCopyDict (void) — init copy dict
  • static void addCopy (const SoFieldContainer *orig, const SoFieldContainer *copy) — adds copy
  • static SoFieldContainer * checkCopy (const SoFieldContainer *orig) — checks copy
  • static SoFieldContainer * findCopy (const SoFieldContainer *orig, const SbBool copyconnections) — finds copy
  • static void copyDone (void) — copy done

⭐ 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) — adds name
  • static void removeName (SoBase *const base, const char *const name) — removes name
  • static void incrementCurrentWriteCounter (void) — increments current write counter
  • static void decrementCurrentWriteCounter (void) — decrements current write counter
  • static SoBase * getNamedBase (const SbName &name, SoType type) — gets named base
  • static int getNamedBases (const SbName &name, SoBaseList &baselist, SoType type) — gets named bases
  • static SbBool read (SoInput *input, SoBase *&base, SoType expectedtype) — reads
  • static void setInstancePrefix (const SbString &c) — sets instance prefix
  • static void setTraceRefs (SbBool trace) — sets trace refs
  • static SbBool getTraceRefs (void) — gets trace refs
  • static SbBool connectRoute (SoInput *input, const SbName &fromnodename, const SbName &fromfieldname, const SbName &tonodename, const SbName &tofieldname) — connects route
  • static SbBool readRoute (SoInput *input) — reads route

🎀 Public Attributes 🎀

  • SoMFFloat screenArea — the screen area attribute, so fetch

💖 Protected Member Functions 💖

  • virtual const SoFieldData * getFieldData (void) const — gets field data
  • virtual ~SoLevelOfDetail () — destructor, bye bestie

💖 Protected Member Functions inherited from SoGroup 💖

  • virtual ~SoGroup () — destructor
  • virtual SbBool readInstance (SoInput *in, unsigned short flags) — reads instance
  • virtual SbBool readChildren (SoInput *in) — reads children
  • virtual void copyContents (const SoFieldContainer *from, SbBool copyconnections) — copies contents
  • virtual SoNotRec createNotRec (void) — creates not rec
  • void setOperation (const SoNotRec::OperationType opType=SoNotRec::UNSPECIFIED, const SoNode *cc=NULL, const SoNode *pc=NULL, const int ci=-1) — sets operation with defaults

💖 Protected Member Functions inherited from SoNode 💖

  • SoNode (void) — constructor
  • virtual ~SoNode () — destructor

💖 Protected Member Functions inherited from SoFieldContainer 💖

  • SoFieldContainer (void) — constructor
  • virtual ~SoFieldContainer () — destructor

💖 Protected Member Functions inherited from SoBase 💖

  • SoBase (void) — constructor
  • virtual ~SoBase () — destructor
  • virtual void destroy (void) — destroy
  • SbBool hasMultipleWriteRefs (void) const — has multiple write refs?
  • SbBool writeHeader (SoOutput *out, SbBool isgroup, SbBool isengine) const — writes header
  • void writeFooter (SoOutput *out) const — writes footer
  • virtual const char * getFileFormatName (void) const — gets file format name

🦋 Static Protected Member Functions 🦋

  • static const SoFieldData ** getFieldDataPtr (void) — gets field data ptr

🦋 Static Protected Member Functions inherited from SoGroup 🦋

  • static const SoFieldData ** getFieldDataPtr (void) — gets field data ptr

🦋 Static Protected Member Functions inherited from SoNode 🦋

  • static const SoFieldData ** getFieldDataPtr (void) — gets field data ptr
  • static void setNextActionMethodIndex (int index) — sets next action method index
  • static int getNextActionMethodIndex (void) — gets next action method index
  • static void incNextActionMethodIndex (void) — increments next action method index
  • static void setCompatibilityTypes (const SoType &nodetype, const uint32_t bitmask) — sets compatibility types

🦋 Static Protected Member Functions inherited from SoBase 🦋

  • static uint32_t getCurrentWriteCounter (void) — gets current write counter
  • static void staticDataLock (void) — locks static data
  • static void staticDataUnlock (void) — unlocks static data

🌈 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 — the children pointer, bestie

👑 Protected Attributes inherited from SoNode 👑

  • SbUniqueId uniqueId — the unique id, no cap

👑 Protected Attributes inherited from SoFieldContainer 👑

  • SbBool isBuiltIn — is built in flag

👑 Static Protected Attributes inherited from SoNode 👑

  • static SbUniqueId nextUniqueId = 1 — next unique id starts at 1
  • static int nextActionMethodIndex = 0 — next action method index starts at 0

✨ Detailed Description ✨

Okay bestie, gather round, because SoLevelOfDetail is that girl. 💅

The SoLevelOfDetail class is used to choose a child based on projected size. That's the whole vibe. That's the assignment. 👑

A level-of-detail mechanism is typically used by application programmers to assist the library in speeding up the rendering. Think of it as you doing the library a solid so it can go faster. 🤝

The way a level-of-detail mechanism works is basically like this:

Several versions of varying complexity of the same geometry / shape is provided by the application programmer in sorted order from "most complex" to "least complex" (where "complex" in this context should be taken to mean more or less detailed in the number of polygons / shapes used for rendering it). So you line them up, most extra first, chillest last. No shuffling. 💖

The runtime rendering system then, upon scene graph traversal, will on-the-fly calculate either the distance from the camera to the 3D-model in question, or the number of pixels in the screen projection of the 3D-model. This value is then used to decide which version of the model to actually render: as the model is moved farther away from the camera, a less detailed version of the model is used. And vice versa, as the model moves closer to the camera, more and more detailed versions of it are rendered. Far away = low effort. Close up = full glam. It's giving adaptive. 🦋

This is under many different circumstances a very effective way to let the application programmer assist to profoundly optimize the rendering of her 3D-scene. Lowkey a glow-up for your frame rate. 🔥

There is of course a trade-off with the level-of-detail technique: more versions of the same 3D model means the scene graph will use up more application memory resources. Also, generating the set of less and less detailed versions of a 3D model from the original is often not a trivial task to do properly. The process is often assisted by software like what Kongsberg Oil & Gas Technologies offers in their Rational Reducer package (http://www.rational-reducer.com). So yeah, you're trading memory and homework for speed. Nothing is free, bestie. 😭

The SoLevelOfDetail node implements the "projected size" variety level-of-detail technique (as opposed to the "object distance" technique, as done by the SoLOD node). The node works by comparing the current projected size of the smallest rectangle covering the bounding box of its child geometry. Along with this set of models of the same shape, a specification of when to switch between them is also provided.

Example scene graph layout:

LevelOfDetail {
  screenArea [ 2000, 500, 50 ]
  DEF version-0 Separator {
    # most complex / detailed / heavy version of subgraph
  }
  DEF version-1 Separator {
    # less complex version of subgraph
  }
  DEF version-2 Separator {
    # even less complex version of subgraph
  }
  DEF version-3 Separator {
    # simplest / "lightest" version of subgraph
  }
}

The way the above sub-scene graph would work would be the following: if the rectangular area around the model's projected bounding box covers more than 2000 pixels (meaning it will be up pretty close to the camera), the most complex version of the model (version-0) would be traversed (and rendered, of course). If the projected area would be between 500 and 2000 pixels, the version-1 model would be used. Ditto if the projected area was between 50 and 500 pixels, the version-2 version of the model would be used. Finally, if the projected bounding box area would be less than 50 square pixels, the presumably least detailed version of the model would be used. Sliding scale of slay, basically. 🌈

(A common "trick" is to let the last of the SoLevelOfDetail node's children be just an empty subgraph, so no geometry will be rendered at all if the model is sufficiently far away. This will of course have a positive effect on the total rendering time for the complete scene graph.) Empty child = free real estate. 🎀

Note that the SoLevelOfDetail::screenArea vector will be influenced by preceding SoComplexity nodes in the following way: if SoComplexity::value is set from 0.0 up to 0.5, lower detail levels than normal will be selected for traversal. If SoComplexity::value is above 0.5, higher level details than normal will be used. An SoComplexity::value equal to 1.0 will cause the first child of SoLevelOfDetail to always be used. So your SoComplexity node is out here influencing decisions upstream. Main character energy fr fr. 👑

As mentioned above, there is one other level-of-detail node in the Coin library: SoLOD. The difference between that one and this is just that instead of projected bounding box area, SoLOD uses the distance between the camera and the object to find out when to switch between the different model versions. Using SoLOD is faster, since figuring out the projected bounding box area needs a certain amount of calculations. But using SoLevelOfDetail is often "better", in the sense that it's really a model's size and visibility in the viewport that determines whether we could switch to a less complex version without losing enough detail that it gives a noticeable visual degradation. Iykyk. 💜

📁 FILE FORMAT/DEFAULTS 📁

LevelOfDetail {
    screenArea 0
}

👀 See also 👀

  • SoLOD

🛠 Constructor & Destructor Documentation 🛠

SoLevelOfDetail::SoLevelOfDetail (void )

Default constructor. Does exactly what it says on the tin, no notes. ✨

SoLevelOfDetail::SoLevelOfDetail (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. So like, a vibe estimate is fine, bestie, it's not graded. 📝

SoLevelOfDetail::~SoLevelOfDetail () [protected], [virtual]

Destructor. Cleanup era. 🧹

🫶 Member Function Documentation 🫶

SoType SoLevelOfDetail::getClassTypeId (void ) [static]

This static method returns the SoType object associated with objects of this class. 💫

SoType SoLevelOfDetail::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 ** SoLevelOfDetail::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.

Not for you, bestie — this one's library business. Move along, nothing to see. 🙈

const SoFieldData * SoLevelOfDetail::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 SoLevelOfDetail::doAction (SoAction * action) [virtual]

This function performs the typical operation of a node for any action. The generalist. The multitasker. 🌀

Reimplemented from SoGroup.

void SoLevelOfDetail::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 SoLevelOfDetail::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. Throwing primitives at OpenGL, iconic behavior honestly. 🔥

Reimplemented from SoGroup.

void SoLevelOfDetail::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 SoLevelOfDetail::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 SoLevelOfDetail::audioRender (SoAudioRenderAction * action) [virtual]

Action method for SoAudioRenderAction.

Does common processing for SoAudioRenderAction action instances.

Reimplemented from SoGroup.

void SoLevelOfDetail::notify (SoNotList * l) [virtual]

Notifies all auditors for this instance when changes are made. Gossip travels fast in this scene graph. 📣

Reimplemented from SoNode.

🎀 Member Data Documentation 🎀

SoMFFloat SoLevelOfDetail::screenArea

The screen area limits for the children. See usage example in main class documentation of SoLevelOfDetail for an explanation of how this vector should be set up correctly.

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

🌸 Author 🌸

Generated automatically by Doxygen for Coin from the source code.

And that's a wrap, bestie! This whole page is from Coin version 4.0.10, dated Thu Jun 25 2026 00:00:00 — and it's the SoLevelOfDetail(3) page, so if you forget which manpage you were reading, it literally says it right there in the corner. 💖 Go forth and level-of-detail responsibly. 🦋✨

📦 where this page comes from