The SoAction class is the base class for all traversal actions. More...

#include <Inventor/actions/SoAction.h>

Inheritance diagram for SoAction:

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 it's apply() method on the root node of the scenegraph (or sub-graph of a scenegraph). The action then traverses the scenegraph from the root node, depth-first and left-to-right, applying it's specific processing at the nodes where it is applicable.

(The SoAction and it's 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 scenegraph 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-)scenegraph that was traversed, which you can then inquire about through methods like SoGetBoundingBoxAction::getBoundingBox(), SoRayPickAction::getPickedPoint(), SoGetPrimitiveCountAction::getTriangleCount(), etc etc.

See the various built-in actions for further information (ie 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, aswell 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 stand-alone example.
//
// The general technique is to inherit SoWriteAction and override it's
// "entry point" into each node of the scenegraph. The granularity of
// the progress callbacks is on a per-node basis, which should usually
// be good enough.
#include <Inventor/SoDB.h>
#include <Inventor/actions/SoWriteAction.h>
#include <Inventor/nodes/SoSeparator.h>
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 <filename>\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

◆ AppliedCode

enum SoAction::AppliedCode

Enumerated values for what the action was applied to.

◆ PathCode

enum SoAction::PathCode

Enumerated values for how the action is applied to a scene graph.

Constructor & Destructor Documentation

◆ ~SoAction()

SoAction::~SoAction ( void )

virtual

Destructor, free resources.

◆ SoAction()

SoAction::SoAction ( void )

protected

Default constructor, does all necessary toplevel initialization.

Member Function Documentation

◆ initClass()

void SoAction::initClass ( void )

static

Initializes the run-time type system for this class, and sets up the enabled elements and action method list.

◆ initClasses()

void SoAction::initClasses ( void )

static

Initialize all the SoAction subclasses. Automatically called from SoAction::initClass().

◆ getClassTypeId()

SoType SoAction::getClassTypeId ( void )

static

Returns the run-time type object associated with instances of this class.

◆ getTypeId()

SoType SoAction::getTypeId ( void ) const

pure virtual

Returns the type identification of an action derived from a class inheriting SoAction. This is used for run-time 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 renderaction
}

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 pre-defined 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 SoCallbackAction, SoIntersectionDetectionAction, SoGLRenderAction, SoRayPickAction, SoVectorizeAction, SoGetMatrixAction, SoHandleEventAction, SoGetBoundingBoxAction, SoGlobalSimplifyAction, SoShapeSimplifyAction, SoGetPrimitiveCountAction, SoSearchAction, SoVectorizePSAction, SoPickAction, SoAudioRenderAction, SoReorganizeAction, SoWriteAction, SoBoxHighlightRenderAction, SoLineHighlightRenderAction, SoSimplifyAction, SoToVRMLAction, and SoToVRML2Action.

◆ isOfType()

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.

◆ apply() [1/4]

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 SoIntersectionDetectionAction, SoVectorizeAction, SoReorganizeAction, SoBoxHighlightRenderAction, SoLineHighlightRenderAction, SoSimplifyAction, SoToVRMLAction, and SoToVRML2Action.

◆ apply() [2/4]

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 SoIntersectionDetectionAction, SoVectorizeAction, SoReorganizeAction, SoBoxHighlightRenderAction, SoLineHighlightRenderAction, SoSimplifyAction, SoToVRMLAction, and SoToVRML2Action.

◆ apply() [3/4]

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 SoIntersectionDetectionAction, SoVectorizeAction, SoReorganizeAction, SoBoxHighlightRenderAction, SoLineHighlightRenderAction, SoSimplifyAction, SoToVRMLAction, and SoToVRML2Action.

◆ apply() [4/4]

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

◆ invalidateState()

void SoAction::invalidateState ( void )

virtual

Invalidates the state, forcing it to be recreated at the next apply() invocation.

Reimplemented in SoGLRenderAction.

◆ nullAction()

void SoAction::nullAction	(	SoAction *	action,
		SoNode *	node
	)

static

This method is used for filling up the lookup tables with void methods.

◆ getWhatAppliedTo()

SoAction::AppliedCode SoAction::getWhatAppliedTo ( void ) const

Returns a code indicating what (node, path, or pathlist) the action instance is being applied to.

◆ getNodeAppliedTo()

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 pathlist), the method returns NULL.

◆ getPathAppliedTo()

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 pathlist), the method returns NULL.

◆ getPathListAppliedTo()

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 pathlist 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)

◆ getOriginalPathListAppliedTo()

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.

◆ isLastPathListAppliedTo()

SbBool SoAction::isLastPathListAppliedTo ( void ) const

This method is not supported in Coin. It should probably have been private in OIV.

◆ getPathCode()

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.

◆ traverse()

void SoAction::traverse ( SoNode *const node )

Traverses a scene graph rooted at node, invoking the action methods of the nodes in the graph.

◆ hasTerminated()

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()

◆ getCurPath()

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.

◆ getState()

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.

◆ getCurPathCode()

SoAction::PathCode SoAction::getCurPathCode ( void ) const

inline

Returns the current traversal path code.

◆ getCurPathTail()

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.

◆ usePathCode()

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.

◆ pushCurPath() [1/2]

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.