NAME
SoAction -
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.
SYNOPSIS
#include <Inventor/actions/SoAction.h>
Inherited by SoAudioRenderAction, SoCallbackAction,
SoGetBoundingBoxAction, SoGetMatrixAction, SoGetPrimitiveCountAction,
SoGLRenderAction, 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=0)
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 sourcecode of
the built-in classes in Coin should also provide 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) 0, n, mwa->nrnodes, mwa->totalnrnodes);
out->write(s.getString());
}
}
int
main(int argc, char ** argv)
{
if (argc < 2) {
(void)fprintf(stderr, ’0sage: %s <filename>0, 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 toplevel initialization.
Member Function Documentation
void SoAction::initClass (void) [static] Initializes the run-time type
system for this class, and sets up the enabled elements and action
method list.
Reimplemented in SoAudioRenderAction, SoBoxHighlightRenderAction,
SoCallbackAction, SoGLRenderAction, SoGetBoundingBoxAction,
SoGetMatrixAction, SoGetPrimitiveCountAction, SoGlobalSimplifyAction,
SoHandleEventAction, SoLineHighlightRenderAction, SoPickAction,
SoRayPickAction, SoReorganizeAction, SoSearchAction,
SoShapeSimplifyAction, SoSimplifyAction, SoToVRML2Action,
SoToVRMLAction, SoWriteAction, SoVectorizeAction, SoVectorizePSAction,
and SoIntersectionDetectionAction.
void SoAction::initClasses (void) [static] Initialize all the SoAction
subclasses. Automatically called from SoAction::initClass().
SoType SoAction::getClassTypeId (void) [static] Returns the run-time type
object associated with instances of this class.
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.
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,
SoLineHighlightRenderAction, SoReorganizeAction, SoSimplifyAction,
SoToVRML2Action, SoToVRMLAction, SoVectorizeAction, and
SoIntersectionDetectionAction.
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,
SoLineHighlightRenderAction, SoReorganizeAction, SoSimplifyAction,
SoToVRML2Action, SoToVRMLAction, SoVectorizeAction, and
SoIntersectionDetectionAction.
void SoAction::apply (const SoPathList & pathlist, SbBool obeysrules = 0)
[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,
SoLineHighlightRenderAction, SoReorganizeAction, SoSimplifyAction,
SoToVRML2Action, SoToVRMLAction, SoVectorizeAction, and
SoIntersectionDetectionAction.
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 pathlist) 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 pathlist),
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 pathlist),
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 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)
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 childindexth 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 childindexth 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 scenegraph 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 scenegraph traversal.
Reimplemented in SoAudioRenderAction, SoCallbackAction,
SoGLRenderAction, SoGetBoundingBoxAction, SoGetMatrixAction,
SoGetPrimitiveCountAction, SoGlobalSimplifyAction, SoHandleEventAction,
SoPickAction, SoRayPickAction, SoReorganizeAction, SoSearchAction,
SoShapeSimplifyAction, SoSimplifyAction, SoToVRML2Action,
SoToVRMLAction, and SoWriteAction.
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.
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
SoAction::state [protected] Pointer to the traversal state instance of the
action.
SoAction::traversalMethods [protected] Stores the list of ’nodetype to
actionmethod’ mappings for the particular action instance.
Author
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