SoGroup(3)

📦

version 4.0.10 · 4 versions

4.0.10 · fedora 43, fedora 44 (latest)
4.0.10 · epel 9
4.0.3 · fedora 43
4.0.7 · fedora 44

✨ SoGroup(3) — Coin manual, but make it bestie-coded ✨

okay so welcome to the SoGroup(3) page from the Coin manual 💖 this is part 1 of 3, so settle in, hydrate, we're doing this 🎀

🌸 NAME 🌸

SoGroup — it's the node class that manages other node instances. a node that parents other nodes, literally the group-chat admin of the scene graph, and it's iconic for it 👑

🦋 SYNOPSIS 🦋

#include <Inventor/nodes/SoGroup.h>

Inherits SoNode.

Inherited by SoArray, SoLOD, SoLevelOfDetail, SoMultipleCopy, SoPathSwitch, SoSeparator, SoSwitch, SoTransformSeparator, SoVRMLLOD, SoVRMLParent, and SoVRMLSwitch. it's giving dynasty, fr fr 👑

💅 Public Member Functions

virtual SoType getTypeId (void) const
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 doAction (SoAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void callback (SoCallbackAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
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 void getPrimitiveCount (SoGetPrimitiveCountAction *action)
virtual void audioRender (SoAudioRenderAction *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 GLRenderBelowPath (SoGLRenderAction *action)
virtual void GLRenderInPath (SoGLRenderAction *action)
virtual void GLRenderOffPath (SoGLRenderAction *action)
virtual void rayPick (SoRayPickAction *action)
virtual void grabEventsSetup (void)
virtual void grabEventsCleanup (void)
virtual void startNotify (void)
virtual void notify (SoNotList *l)
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
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

quick note on that one: isOfType Returns TRUE if the type of this object is either of the same type or inherited from type. so like, type-checking but make it family-tree ✨

⭐ Static Public Member Functions ⭐

static SoType getClassTypeId (void)
static void initClass (void)

initClass — sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. it's the lil setup ritual bestie 🫶

🌈 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)
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)

and initClass again — same vibe: 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 `SoFieldContainer`

static void initClass (void)
static SoType getClassTypeId (void)
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)

initClass — sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
getClassTypeId — this static method returns the SoType object associated with objects of this class. the ✨identity document✨ of the class ngl

🦋 Static Public Member Functions inherited from `SoBase`

static void initClass (void)
static SoType getClassTypeId (void)
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)

initClass — sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
getClassTypeId — this static method returns the SoType object associated with objects of this class.

🎀 Protected Member Functions 🎀

virtual const SoFieldData * getFieldData (void) const
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 `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)

🫶 Protected Attributes 🫶

SoChildList * children

🌸 Protected Attributes inherited from `SoNode`

SbUniqueId uniqueId

🎀 Protected Attributes inherited from `SoFieldContainer`

SbBool isBuiltIn

👑 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 }

🌈 Static Protected Attributes inherited from `SoNode`

static SbUniqueId nextUniqueId = 1
static int nextActionMethodIndex = 0

okay bestie that's the whole synopsis dump, and part 2 is coming right up so don't go anywhere 💖

✨ Detailed Description ✨

Okay so bestie, listen. The SoGroup class is literally a node that manages other node instances. Like it's the momager of the scene graph. 👑

The internal scene data structures in Coin are managed as directed graphs. The graphs are built by setting up a hierarchy through the use of group nodes (either of this type, or from subclasses like SoSeparator) which is then traversed when applying actions (like SoGLRenderAction) to it. So it's giving family tree but for 3D. 🌳

SoGroup, SoSeparator, and other classes derived from SoGroup, are the "tools" the application programmer uses when making the layout of the scene graph. Slay. 💅

An often asked question about SoGroup nodes is: "Why is there no SoGroup::getParent() method?" The answer to this is that nodes in the scene graph can have multiple parents, so a simple getParent() method wouldn't work. If you have a node pointer (or other node identification) of a node that you want to remove from the scene graph, what you need to do is to use an SoSearchAction to find all paths down to the node, and then invoke SoGroup::removeChild() from all found parents of the node. Periodt. 💅

The function would look something like this:

void getParents(SoNode * node, SoNode * root, SoPathList & parents)
{
  SoSearchAction sa;
  sa.setNode(node);
  sa.setInterest(SoSearchAction::ALL);
  sa.apply(root);
  parents = sa.getPaths();
}

Or if you know that your node of interest has only a single parent:

SoGroup * getParent(SoNode * node, SoNode * root)
{
  SoSearchAction sa;
  sa.setNode(node);
  sa.setInterest(SoSearchAction::FIRST);
  sa.apply(root);
  SoPath * p = sa.getPath();
  assert(p && "not found");
  if (p->getLength() < 2) { return NULL; } // no parent
  return (SoGroup *)p->getNodeFromTail(1);
}

An important note about a potential problem using SoGroup nodes which it is not common to stumble on, but which makes hard to find bugs when one does: you should not change the scene graph layout during any action traversal, as that is not allowed by the internal Coin code. I.e. do not use addChild(), removeChild(), insertChild() or replaceChild() from any callback that is triggered directly or indirectly from an action traversal. The most common way of getting hit by this error, would be something like the following (simplified) example:

#include <Inventor/Qt/SoQt.h>
#include <Inventor/Qt/viewers/SoQtExaminerViewer.h>

#include <Inventor/nodes/SoEventCallback.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoCone.h>
#include <Inventor/manips/SoPointLightManip.h>
#include <Inventor/events/SoMouseButtonEvent.h>

SoPointLightManip * global_pointlightmanip;
SoSeparator * global_root;

// Remove point light when clicking right mouse button.
static void
mySelectionC(void * ud, SoEventCallback * n)
{
  const SoMouseButtonEvent * mbe = (SoMouseButtonEvent*) n->getEvent();

  if ((mbe->getButton() == SoMouseButtonEvent::BUTTON2) &&
      (mbe->getState() == SoButtonEvent::DOWN)) {
    if (global_pointlightmanip) {
      global_root->removeChild(global_pointlightmanip);
      global_pointlightmanip = NULL;
    }
  }
}

int
main(int argc, char ** argv)
{
  QWidget * window = SoQt::init(argv[0]);

  global_root = new SoSeparator;
  global_root->ref();

  SoEventCallback * ecb = new SoEventCallback;
  ecb->addEventCallback(SoMouseButtonEvent::getClassTypeId(), mySelectionC, 0);
  global_root->addChild(ecb);

  global_root->addChild(new SoCone);

  global_pointlightmanip = new SoPointLightManip;
  global_root->addChild(global_pointlightmanip);

  SoQtExaminerViewer * viewer = new SoQtExaminerViewer(window);
  viewer->setSceneGraph(global_root);
  viewer->show();

  SoQt::show(window);
  SoQt::mainLoop();

  global_root->unref();
  delete viewer;

  return 0;
}

What happens in the above case is this: when clicking with the right mouse button, the SoQtExaminerViewer converts the Qt event to a Coin event, which is sent down the scene graph with an SoHandleEventAction. The action traversal reaches the "global_root" SoSeparator node, where it sees that it should further traverse 3 child nodes (first the SoEventCallback, then the SoCone, then the SoPointLightManip). When it then traverses the SoEventCallback, the mySelectionC() callback will be invoked, which removes the last child. But the SoHandleEventAction will still continue its traversal as if the global_root node has 3 children -- and the code will crash. 💀

(This exact example would perhaps be straight-forward to handle internally in Coin, but there are other ways to change the scene graph layout that are very difficult to handle properly. So in general, changing layout during action traversal is not allowed.)

What to do in these cases is to change the code inside the callback to not do any operations that immediately changes the layout of the scene graph, but to delay it for after the traversal is done. This can e.g. be done by using a Coin sensor. 🧚

FILE FORMAT/DEFAULTS:

Group {
}

🎀 Constructor & Destructor Documentation 🎀

`SoGroup::SoGroup (void )`

Default constructor. It's giving blank slate, no children, just vibes. ✨

`SoGroup::SoGroup (int nchildren)`

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 ballpark, bestie. 👑

`SoGroup::~SoGroup () [protected], [virtual]`

Destructor. It cleans up. Bye bestie. 👋

💖 Member Function Documentation 💖

`SoType SoGroup::getClassTypeId (void ) [static]`

This static method returns the SoType object associated with objects of this class. So you can flex the type. 💅

`SoType SoGroup::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.

Implements SoBase.

Reimplemented in SoAnnotation, SoArray, SoBlinker, SoExtSelection, SoGeoSeparator, SoLevelOfDetail, SoLocateHighlight, SoLOD, SoMultipleCopy, SoPathSwitch, SoSelection, SoSeparator, SoShadowGroup, SoSwitch, SoTransformSeparator, SoVRMLAnchor, SoVRMLBillboard, SoVRMLCollision, SoVRMLGroup, SoVRMLLOD, SoVRMLParent, SoVRMLSwitch, SoVRMLTransform, and SoWWWAnchor.

`const SoFieldData ** SoGroup::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. Like, it's giving backstage pass only. 🙈

Returns the SoFieldData class which holds information about fields in this node.

`const SoFieldData * SoGroup::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. So if there's nothing, you get NULL, no cap. 🚫

Reimplemented from SoFieldContainer.

`void SoGroup::addChild (SoNode * node) [virtual]`

Append a child node to the list of children nodes this group node is managing. It's like adding a new member to the group chat. 🫶

Please note that this method is not virtual in the original SGI Inventor API. So yeah, SGI said no virtual, Coin said hold my matcha. 🍵