--- name: "SoAction" section: "3" platform: "linux" package: "coin" version: "1:4.0.10-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/SoAction" --- # SoAction(3) The SoAction class is the base class for all traversal actions. ## NAME SoAction - The **SoAction** class is the base class for all traversal actions. ## SYNOPSIS \#include \ Inherited by **SoAudioRenderAction**, **SoCallbackAction**, **SoGLRenderAction**, **SoGetBoundingBoxAction**, **SoGetMatrixAction**, **SoGetPrimitiveCountAction**, **SoHandleEventAction**, **SoIntersectionDetectionAction**, **SoPickAction**, **SoSearchAction**, **SoSimplifyAction**, **SoToVRMLAction**, and **SoWriteAction**. ### Public Types enum **AppliedCode** { **NODE** = 0, **PATH** = 1, **PATH\_LIST** = 2 }\ enum **PathCode** { **NO\_PATH** = 0, **IN\_PATH** = 1, **BELOW\_PATH** = 2, **OFF\_PATH** = 3 }\ ### Public Member Functions virtual **~SoAction** (void)\ virtual **SoType** **getTypeId** (void) const =0\ virtual SbBool **isOfType** (**SoType** type) const\ virtual void **apply** (**SoNode** \*root)\ virtual void **apply** (**SoPath** \*path)\ virtual void **apply** (const **SoPathList** &pathlist, SbBool obeysrules=FALSE)\ void **apply** (**SoAction** \*beingApplied)\ virtual void **invalidateState** (void)\ **AppliedCode** **getWhatAppliedTo** (void) const\ **SoNode** \* **getNodeAppliedTo** (void) const\ **SoPath** \* **getPathAppliedTo** (void) const\ const **SoPathList** \* **getPathListAppliedTo** (void) const\ const **SoPathList** \* **getOriginalPathListAppliedTo** (void) const\ SbBool **isLastPathListAppliedTo** (void) const\ **PathCode** **getPathCode** (int &numindices, const int \*&indices)\ void **traverse** (**SoNode** \*const node)\ SbBool **hasTerminated** (void) const\ const **SoPath** \* **getCurPath** (void)\ **SoState** \* **getState** (void) const\ **PathCode** **getCurPathCode** (void) const\ virtual **SoNode** \* **getCurPathTail** (void)\ void **usePathCode** (int &numindices, const int \*&indices)\ void **pushCurPath** (const int childindex, **SoNode** \*node=NULL)\ void **popCurPath** (const **PathCode** prevpathcode)\ void **pushCurPath** (void)\ void **popPushCurPath** (const int childindex, **SoNode** \*node=NULL)\ void **popCurPath** (void)\ void **switchToPathTraversal** (**SoPath** \*path)\ void **switchToNodeTraversal** (**SoNode** \*node)\ ### Static Public Member Functions static void **initClass** (void)\ static void **initClasses** (void)\ static **SoType** **getClassTypeId** (void)\ static void **nullAction** (**SoAction** \*action, **SoNode** \*node)\ ### Protected Member Functions **SoAction** (void)\ virtual void **beginTraversal** (**SoNode** \*node)\ virtual void **endTraversal** (**SoNode** \*node)\ void **setTerminated** (const SbBool flag)\ virtual const **SoEnabledElementsList** & **getEnabledElements** (void) const\ virtual SbBool **shouldCompactPathList** (void) const\ ### Static Protected Member Functions static **SoEnabledElementsList** \* **getClassEnabledElements** (void)\ static **SoActionMethodList** \* **getClassActionMethods** (void)\ ### Protected Attributes **SoState** \* **state**\ **SoActionMethodList** \* **traversalMethods**\ ## Detailed Description The **SoAction** class is the base class for all traversal actions. Applying actions is the basic mechanism in Coin for executing various operations on scene graphs or paths within scene graphs, including search operations, rendering, interaction through picking, etc. The basic operation is to instantiate an action, set it up with miscellaneous parameters if necessary, then call its **apply()** method on the root node of the scene graph (or subgraph of a scene graph). The action then traverses the scene graph from the root node, depth-first and left-to-right, applying its specific processing at the nodes where it is applicable. (The **SoAction** and its derived classes in Coin is an implementation of the design pattern commonly known as the "Visitor" pattern.) Here's a simple example that shows how to use the **SoWriteAction** to dump a scene graph in the Inventor format to a file: ``` int write_scenegraph(const char * filename, SoNode * root) { SoOutput output; if (!output.openFile(filename)) return 0; // This is where the action is. ;-) SoWriteAction wa(&output); wa.apply(root); return 1; } ``` After traversal, some action types have stored information about the (sub-)scene graph that was traversed, which you can then inquire about through methods like **SoGetBoundingBoxAction::getBoundingBox()**, **SoRayPickAction::getPickedPoint()**, **SoGetPrimitiveCountAction::getTriangleCount()**, etc. See the various built-in actions for further information (i.e. the subclasses of this class), or look at the example code applications of the Coin library to see how actions are generally used. For extending the Coin library with your own classes, we strongly recommend that you make yourself acquainted with the excellent The Inventor Toolmaker book (ISBN 0-201-62493-1), which describes the tasks involved in detail. This book was written by the original SGI Inventor designers and explains many of the underlying design ideas, as well as having lots of hands-on examples on how to extend the Coin toolkit in ways that are true to the fundamental design ideas. (The Inventor Toolmaker is also available at SGI's online library, at no cost. See Download The Inventor Toolmaker.) Reading the source code of the built-in classes in Coin should also prove very helpful.\ \ The following example shows the basic outline on how to set up your own extension action class: ``` // This is sample code on how you can get progress indication on Coin // export operations by extending the library with your own action // class. The new class inherits SoWriteAction. The code is presented // as a standalone example. // // The general technique is to inherit SoWriteAction and override its // "entry point" into each node of the scene graph. The granularity of // the progress callbacks is on a per node basis, which should usually // be good enough. #include #include #include class MyWriteAction : public SoWriteAction { SO_ACTION_HEADER(SoWriteAction); public: MyWriteAction(SoOutput * out); virtual ~MyWriteAction(); static void initClass(void); protected: virtual void beginTraversal(SoNode * node); private: static void actionMethod(SoAction *, SoNode *); int nrnodes; int totalnrnodes; }; SO_ACTION_SOURCE(MyWriteAction); MyWriteAction::MyWriteAction(SoOutput * out) : SoWriteAction(out) { SO_ACTION_CONSTRUCTOR(MyWriteAction); } MyWriteAction::~MyWriteAction() { } void MyWriteAction::initClass(void) { SO_ACTION_INIT_CLASS(MyWriteAction, SoWriteAction); SO_ACTION_ADD_METHOD(SoNode, MyWriteAction::actionMethod); } void MyWriteAction::beginTraversal(SoNode * node) { this->nrnodes = 0; this->totalnrnodes = 0; SoWriteAction::beginTraversal(node); } void MyWriteAction::actionMethod(SoAction * a, SoNode * n) { // To abort the export process in mid-writing, we could just avoid // calling in to the SoNode::writeS() method. SoNode::writeS(a, n); MyWriteAction * mwa = (MyWriteAction *)a; SoOutput * out = mwa->getOutput(); if (out->getStage() == SoOutput::COUNT_REFS) { mwa->totalnrnodes++; } else { // (out->getStage() == SoOutput::WRITE) mwa->nrnodes++; SbString s; s.sprintf(" # wrote node %p (%d/%d) \n", n, mwa->nrnodes, mwa->totalnrnodes); out->write(s.getString()); } } int main(int argc, char ** argv) { if (argc < 2) { (void)fprintf(stderr, "\n\nUsage: %s \n\n", argv[0]); exit(1); } SoDB::init(); MyWriteAction::initClass(); SoInput in; if (!in.openFile(argv[1])) { exit(1); } SoSeparator * root = SoDB::readAll(&in); if (!root) { exit(1); } root->ref(); SoOutput out; MyWriteAction mwa(&out); mwa.apply(root); root->unref(); return 0; } ``` ## Member Enumeration Documentation ### enum SoAction::AppliedCode Enumerated values for what the action was applied to. ### enum SoAction::PathCode Enumerated values for how the action is applied to a scene graph. ## Constructor & Destructor Documentation ### SoAction::~SoAction (void ) \[virtual\] Destructor, free resources. ### SoAction::SoAction (void ) \[protected\] Default constructor, does all necessary top level initialization. ## Member Function Documentation ### void SoAction::initClass (void ) \[static\] Initializes the runtime type system for this class, and sets up the enabled elements and action method list. ### void SoAction::initClasses (void ) \[static\] Initialize all the **SoAction** subclasses. Automatically called from **SoAction::initClass()**. ### SoType SoAction::getClassTypeId (void ) \[static\] Returns the runtime type object associated with instances of this class. ### virtual SoType SoAction::getTypeId (void ) const \[pure virtual\] Returns the type identification of an action derived from a class inheriting **SoAction**. This is used for runtime type checking and "downward" casting. Usage example: ``` void bar(SoAction * action) { if (action->getTypeId() == SoGLRenderAction::getClassTypeId()) { // safe downward cast, know the type SoGLRenderAction * glrender = (SoGLRenderAction *)action; } return; // ignore if not render action } ``` For application programmers wanting to extend the library with new actions: this method needs to be overridden in *all* subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the predefined macros available through Inventor/nodes/SoSubAction.h: SO\_ACTION\_SOURCE, SO\_ACTION\_INIT\_CLASS and SO\_ACTION\_CONSTRUCTOR. For more information on writing Coin extensions, see the **SoAction** class documentation. Returns the actual type id of an object derived from a class inheriting **SoAction**. Needs to be overridden in *all* subclasses. Implemented in **SoAudioRenderAction**, **SoBoxHighlightRenderAction**, **SoCallbackAction**, **SoGetBoundingBoxAction**, **SoGetMatrixAction**, **SoGetPrimitiveCountAction**, **SoGlobalSimplifyAction**, **SoGLRenderAction**, **SoHandleEventAction**, **SoIntersectionDetectionAction**, **SoLineHighlightRenderAction**, **SoPickAction**, **SoRayPickAction**, **SoReorganizeAction**, **SoSearchAction**, **SoShapeSimplifyAction**, **SoSimplifyAction**, **SoToVRML2Action**, **SoToVRMLAction**, **SoVectorizeAction**, **SoVectorizePSAction**, and **SoWriteAction**. ### SbBool SoAction::isOfType (SoType type) const \[virtual\] Returns TRUE if the type of this object is either of the same type or a subclass of *type*. ### void SoAction::apply (SoNode \* root) \[virtual\] Applies the action to the scene graph rooted at *root*. Note that you should *not* apply an action to a node with a zero reference count. The behavior in that case is undefined. Reimplemented in **SoBoxHighlightRenderAction**, **SoIntersectionDetectionAction**, **SoLineHighlightRenderAction**, **SoReorganizeAction**, **SoSimplifyAction**, **SoToVRML2Action**, **SoToVRMLAction**, and **SoVectorizeAction**. ### void SoAction::apply (SoPath \* path) \[virtual\] Applies the action to the parts of the graph defined by *path*. Note that an **SoPath** will also contain all nodes that may influence e.g. geometry nodes in the path. So for instance applying an **SoGLRenderAction** on an **SoPath** will render that path as expected in the view, where geometry will get its materials, textures, and other appearance settings correctly. If the *path* ends in an **SoGroup** node, the action will also traverse the tail node's children. Reimplemented in **SoBoxHighlightRenderAction**, **SoIntersectionDetectionAction**, **SoLineHighlightRenderAction**, **SoReorganizeAction**, **SoSimplifyAction**, **SoToVRML2Action**, **SoToVRMLAction**, and **SoVectorizeAction**. ### void SoAction::apply (const SoPathList & pathlist, SbBool obeysrules = FALSE) \[virtual\] Applies action to the graphs defined by *pathlist*. If *obeysrules* is set to TRUE, *pathlist* must obey the following four conditions (which is the case for path lists returned from search actions for non-group nodes and path lists returned from picking actions): All paths must start at the same head node. All paths must be sorted in traversal order. The paths must be unique. No path can continue through the end point of another path. **See also** **SoAction::apply(SoPath \* path)** Reimplemented in **SoBoxHighlightRenderAction**, **SoIntersectionDetectionAction**, **SoLineHighlightRenderAction**, **SoReorganizeAction**, **SoSimplifyAction**, **SoToVRML2Action**, **SoToVRMLAction**, and **SoVectorizeAction**. ### void SoAction::apply (SoAction \* beingApplied) Applies this action object to the same as *beingApplied* is being applied to. This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.\ **Since** Coin 2.1 ### void SoAction::invalidateState (void ) \[virtual\] Invalidates the state, forcing it to be recreated at the next **apply()** invocation. Reimplemented in **SoGLRenderAction**. ### void SoAction::nullAction (SoAction \* action, SoNode \* node) \[static\] This method is used for filling up the lookup tables with void methods. ### SoAction::AppliedCode SoAction::getWhatAppliedTo (void ) const Returns a code indicating what (node, path, or path list) the action instance is being applied to. ### SoNode \* SoAction::getNodeAppliedTo (void ) const Returns a pointer to the node the action is being applied to. If action is not being applied to a node (but a path or a path list), the method returns NULL. ### SoPath \* SoAction::getPathAppliedTo (void ) const Returns the pointer to the path the action is being applied to. The path is managed by the action instance and should not be destroyed or modified by the caller. If action is not being applied to a path (but a node or a path list), the method returns NULL. ### const SoPathList \* SoAction::getPathListAppliedTo (void ) const Returns the pointer to the path list the action is currently being applied to. The path list is managed by the action instance and should not be destroyed or modified by the caller. If action is not being applied to a path list (but a node or a path), the method returns NULL. The returned path list pointer need not be equal to the list **apply()** was called with, as the action may have reorganized the path list for efficiency reasons. **See also** void **SoAction::apply(const SoPathList &, SbBool)** ### const SoPathList \* SoAction::getOriginalPathListAppliedTo (void ) const Returns a pointer to the original path list the action is being applied to. If the action is not being applied to a path list (but a node or a path), the method returns NULL. ### SbBool SoAction::isLastPathListAppliedTo (void ) const This method is not supported in Coin. It should probably have been private in OIV. ### SoAction::PathCode SoAction::getPathCode (int & numindices, const int \*& indices) Returns a code that indicates where the current node lies with respect to the path(s) the action is being applied to. The arguments *indices* and *numindices* are only set if the method returns IN\_PATH. ### void SoAction::traverse (SoNode \*const node) Traverses a scene graph rooted at *node*, invoking the action methods of the nodes in the graph. ### SbBool SoAction::hasTerminated (void ) const Returns TRUE if the action was prematurely terminated. Note that the termination flag will be FALSE if the action simply completed its run over the scene graph in the "ordinary" fashion, i.e. was not explicitly aborted from any of the nodes in the graph. **See also** **setTerminated()** ### const SoPath \* SoAction::getCurPath (void ) Returns a pointer to the path generated during traversal, from the root of the traversed graph to the current node. ### SoState \* SoAction::getState (void ) const Returns a pointer to the state of the action instance. The state contains the current set of elements used during traversal. ### SoAction::PathCode SoAction::getCurPathCode (void ) const \[inline\] Returns the current traversal path code. ### SoNode \* SoAction::getCurPathTail (void ) \[virtual\] *This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.*\ Reimplemented in **SoCallbackAction**. ### void SoAction::usePathCode (int & numindices, const int \*& indices) *This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.*\ ### void SoAction::pushCurPath (const int childindex, SoNode \* node = NULL) Get ready to traverse the *childindex'th* child. Use this method if the path code might change as a result of this. This method is very internal. Do not use unless you know what you're doing. ### void SoAction::popCurPath (const PathCode prevpathcode) Pops the current path, and sets the path code to *prevpathcode*. This method is very internal. Do not use unless you know what you're doing. ### void SoAction::pushCurPath (void ) Pushes a NULL node onto the current path. Use this before traversing all children when you know that the path code will not change while traversing children. This method is very internal. Do not use unless you know what you're doing. ### void SoAction::popPushCurPath (const int childindex, SoNode \* node = NULL) Get ready to traverse the *childindex'th* child. Use this method if you know the path code will not change as a result of this. This method is very internal. Do not use unless you know what you're doing. ### void SoAction::popCurPath (void ) Pops of the last child in the current path. Use this if you know the path code hasn't changed since the current path was pushed. This method is very internal. Do not use unless you know what you're doing. ### void SoAction::switchToPathTraversal (SoPath \* path) Store our state, traverse the given *path*, restore our state and continue traversal. ### void SoAction::switchToNodeTraversal (SoNode \* node) Store our state, traverse the subgraph rooted at the given *node*, restore our state and continue traversal. ### void SoAction::beginTraversal (SoNode \* node) \[protected\], \[virtual\] This virtual method is called from **SoAction::apply()**, and is the entry point for the actual scene graph traversal. It can be overridden to initialize the action at traversal start, for specific initializations in the action subclasses inheriting **SoAction**. Default method just calls **traverse()**, which any overridden implementation of the method must do too (or call **SoAction::beginTraversal()**) to trigger the scene graph traversal. Reimplemented in **SoAudioRenderAction**, **SoCallbackAction**, **SoGetBoundingBoxAction**, **SoGetMatrixAction**, **SoGetPrimitiveCountAction**, **SoGlobalSimplifyAction**, **SoGLRenderAction**, **SoHandleEventAction**, **SoPickAction**, **SoRayPickAction**, **SoReorganizeAction**, **SoSearchAction**, **SoShapeSimplifyAction**, **SoSimplifyAction**, **SoToVRML2Action**, **SoToVRMLAction**, and **SoWriteAction**. ### void SoAction::endTraversal (SoNode \* node) \[protected\], \[virtual\] This virtual method can be overridden to execute code after the scene graph traversal. Default method does nothing. Reimplemented in **SoGLRenderAction**. ### void SoAction::setTerminated (const SbBool flag) \[protected\] Set the termination flag. Typically set to TRUE from nodes upon special conditions being met during scene graph traversal -- like the correct node being found when doing **SoSearchAction** traversal or when grabbing the event from an **SoHandleEventAction**. **See also** **hasTerminated()** ### const SoEnabledElementsList & SoAction::getEnabledElements (void ) const \[protected\], \[virtual\] Returns a list of the elements used by action instances of this class upon traversal operations. Reimplemented in **SoAudioRenderAction**, **SoBoxHighlightRenderAction**, **SoCallbackAction**, **SoGetBoundingBoxAction**, **SoGetMatrixAction**, **SoGetPrimitiveCountAction**, **SoGlobalSimplifyAction**, **SoGLRenderAction**, **SoHandleEventAction**, **SoIntersectionDetectionAction**, **SoLineHighlightRenderAction**, **SoPickAction**, **SoRayPickAction**, **SoReorganizeAction**, **SoSearchAction**, **SoShapeSimplifyAction**, **SoSimplifyAction**, **SoToVRML2Action**, **SoToVRMLAction**, **SoVectorizeAction**, **SoVectorizePSAction**, and **SoWriteAction**. ### SbBool SoAction::shouldCompactPathList (void ) const \[protected\], \[virtual\] *This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.*\ ### SoEnabledElementsList \* SoAction::getClassEnabledElements (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.*\ This method not available in the original OIV API, see **SoSubAction.h** for explanation. ### SoActionMethodList \* SoAction::getClassActionMethods (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.*\ This method not available in the original OIV API, see **SoSubAction.h** for explanation. ## Member Data Documentation ### SoState\* SoAction::state \[protected\] Pointer to the traversal state instance of the action. ### SoActionMethodList\* SoAction::traversalMethods \[protected\] Stores the list of "nodetype to actionmethod" mappings for the particular action instance. ## Author Generated automatically by Doxygen for Coin from the source code.