Provided by: libcoin60-doc_3.1.3-2_all bug

NAME

       SoGetBoundingBoxAction -

       The SoGetBoundingBoxAction class calculates bounding boxes for nodes and subgraphs.

       If this action is applied to a path or scene graph root, it will calculate the bounding
       box and the center point of the geometry contained within the scene.

SYNOPSIS

       #include <Inventor/actions/SoGetBoundingBoxAction.h>

       Inherits SoAction.

   Public Types
       enum ResetType { TRANSFORM =  0x1, BBOX =  0x2, ALL =  TRANSFORM | BBOX }

   Public Member Functions
       SoGetBoundingBoxAction (const SbViewportRegion &vp)
       virtual ~SoGetBoundingBoxAction (void)
       void setViewportRegion (const SbViewportRegion &newregion)
       const SbViewportRegion & getViewportRegion (void) const
       SbBox3f getBoundingBox (void) const
       SbXfBox3f & getXfBoundingBox (void)
       const SbVec3f & getCenter (void) const
       void setInCameraSpace (const SbBool flag)
       SbBool isInCameraSpace (void) const
       void setResetPath (const SoPath *path, const SbBool resetbefore=TRUE, const ResetType
           what=ALL)
       const SoPath * getResetPath (void) const
       SbBool isResetPath (void) const
       SbBool isResetBefore (void) const
       SoGetBoundingBoxAction::ResetType getWhatReset (void) const
       void checkResetBefore (void)
       void checkResetAfter (void)
       void extendBy (const SbBox3f &box)
       void extendBy (const SbXfBox3f &box)
       void setCenter (const SbVec3f &center, const SbBool transformcenter)
       SbBool isCenterSet (void) const
       void resetCenter (void)

   Static Public Member Functions
       static void initClass (void)

   Protected Member Functions
       virtual void beginTraversal (SoNode *node)

Detailed Description

       The SoGetBoundingBoxAction class calculates bounding boxes for nodes and subgraphs.

       If this action is applied to a path or scene graph root, it will calculate the bounding
       box and the center point of the geometry contained within the scene.

       You don't have to apply an SoGetBoundingBoxAction to the root of a scene. When using the
       action, you will get the bounding box of the node you are applying it to and that node's
       sub-tree in the scene graph (if any).

       The calculated bounding box will be in the local coordinates of that sub-tree. If applying
       it to a scene graph root node, the calculated bounding box will be in global coordinates.

       The use of bounding boxes is ubiquitous within the Coin library. It is needed for the
       correct execution of and for performance enhancements during rendering, picking, caching,
       culling, etc.

       SoSeparator nodes are aggressively caching the results of bounding box calculations, so
       that they are really only re-calculated whenever the scenegraph rooted below any
       SoSeparator node has been modified. This means that applying this action to scenegraphs,
       or parts of scenegraphs, should be very quick on successive runs for 'static' parts of the
       scene.

       Note that the algorithm used is not guaranteed to always give an exact bounding box: it
       combines bounding boxes in pairs and extends one of them to contain the other. Since the
       boxes need not be parallel to the principal axes the new box might not be a perfect fit
       for the box not extended (it's coordinate system has been changed).

       Note also that what is returned from getBoundingBox() will be projected so as to be
       oriented along the principal axes, which can often cause it to become quite a lot larger
       than what it was before projection. For client code to obtain the best bounding box that
       Coin can calculate (and which will usually be exact), you need to use the
       getXfBoundingBox() method after having applied the SoGetBoundingBoxAction.

       See also:
           SoSeparator::boundingBoxCaching

Member Enumeration Documentation

   enum SoGetBoundingBoxAction::ResetType This API member is considered internal to the library,
       as it is not likely to be of interest to the application programmer.

Constructor & Destructor Documentation

   SoGetBoundingBoxAction::SoGetBoundingBoxAction (const SbViewportRegion &vp) Constructor.
       It might seem unnecessary to have to pass in a viewport region argument to calculate
       bounding boxes, but there is a good reason for this: a few shape nodes needs to know the
       viewport region to calculate their bounding box -- these include SoText2 and SoImage,
       among others.

       What is particular about these shapes is that they are fundamentally 2D shapes, but they
       are being rendered on the screen 'surface' as if they were in a 3D scene. (This is
       possible because we can match each pixel's depth value against the 3D shapes in the
       scene.)

       To compute an accurate 3D bounding box of a shape rendered in 2D on the screen 'surface',
       you need to 'de-project' the screen-space area it occupies to a 2D rectangle placed at
       some depth in the scene. This 'de-projecting' operation needs to know about the dimensions
       of the viewport.

       Also, some 3D shapes like for instance SoNurbsSurface, get slightly distorted if there's
       an SoComplexity node in the scenegraph with the SoComplexity::value field set to
       SCREEN_SPACE. Then it is also necessary to know the viewport region to find out how to
       accurately calculate the bounding box of those shapes.

       You would usually want to pass in a viewport region equal to the layout of the current
       renderarea canvas. If you have a viewer or So available, you can get hold of the viewport
       region data simply by doing

            const SbViewportRegion & vpreg = viewer->getViewportRegion();

       (If you don't have a viewer or renderarea available in your application at the point where
       you want to get the bounding box, it probably doesn't matter much what you set it to. The
       accuracy of the bounding box calculation might be slightly wrong versus the actual
       rendered appearance of the scene, but this is usually not noticable.)

   SoGetBoundingBoxAction::~SoGetBoundingBoxAction (void) [virtual] Destructor.

Member Function Documentation

   void SoGetBoundingBoxAction::initClass (void) [static] Initializes the run-time type system
       for this class, and sets up the enabled elements and action method list.
       Reimplemented from SoAction.

   void SoGetBoundingBoxAction::setViewportRegion (const SbViewportRegion &newregion) Set a new
       viewport region with this method, if it has changed from the one passed in with the
       constructor.
   const SbViewportRegion & SoGetBoundingBoxAction::getViewportRegion (void) const Returns the
       viewport region used by the action instance.
   SbBox3f SoGetBoundingBoxAction::getBoundingBox (void) const Returns the projected bounding box
       after (or during) traversal.
   SbXfBox3f & SoGetBoundingBoxAction::getXfBoundingBox (void) Returns the bounding box and
       transformation matrix to global coordinates. Use after (or during) traversal.
   const SbVec3f & SoGetBoundingBoxAction::getCenter (void) const Returns center point of scene
       after the action has been applied.
       This might differ from the geometric center of the bounding box, as shape nodes may
       'weight' the center point according to various criteria (i.e. a faceset could for instance
       weight the center point according to the area within its bounding box where there are more
       polygons).

   void SoGetBoundingBoxAction::setInCameraSpace (const SbBoolon) Sets whether the returned
       bounding box should be calculated in the coordinate system of the camera space or not.
   SbBool SoGetBoundingBoxAction::isInCameraSpace (void) const Returns whether the bounding box
       returned is to be in camera space.
   void SoGetBoundingBoxAction::setResetPath (const SoPath *path, const SbBoolresetbefore = TRUE,
       const ResetTypewhat = ALL) Forces the computed bounding box to be reset and the
       transformation to be identity before or after the tail node of path, depending on the
       resetbefore argument. NULL can be specified for the path argument to disable this
       behavior.
       See also:
           getResetPath(), isResetPath(), isResetBefore(), getWhatReset()

   const SoPath * SoGetBoundingBoxAction::getResetPath (void) const Returns the reset path (or
       NULL).
       See also:
           setResetPath(), isResetPath(), isResetBefore(), getWhatReset()

   SbBool SoGetBoundingBoxAction::isResetPath (void) const Returns whether a reset path is set or
       not.
       See also:
           setResetPath(), getResetPath(), isResetBefore(), getWhatReset()

   SbBool SoGetBoundingBoxAction::isResetBefore (void) const Returns whether the bounding box and
       transformation is reset before or after the tail node of the reset path.
       See also:
           setResetPath(), getResetPath(), isResetPath(), getWhatReset()

   SoGetBoundingBoxAction::ResetType SoGetBoundingBoxAction::getWhatReset (void) const Returns
       what type of reset has been specified for the reset path.
       See also:
           setResetPath(), getResetPath(), isResetPath(), isResetBefore()

   void SoGetBoundingBoxAction::checkResetBefore (void) This API member is considered internal to
       the library, as it is not likely to be of interest to the application programmer.
       Called before node traversal of each node (from SoNode action method).

   void SoGetBoundingBoxAction::checkResetAfter (void) This API member is considered internal to
       the library, as it is not likely to be of interest to the application programmer.
       Called after node traversal of each node (from SoNode action method).

   void SoGetBoundingBoxAction::extendBy (const SbBox3f &box) Extend bounding box by the given
       box. Called from nodes during traversal.
       Should usually not be of interest to application programmers, unless you're extending Coin
       with your own shapenode extension classes.

   void SoGetBoundingBoxAction::extendBy (const SbXfBox3f &box) This is an overloaded member
       function, provided for convenience. It differs from the above function only in what
       argument(s) it accepts.
   void SoGetBoundingBoxAction::setCenter (const SbVec3f &centerarg, const SbBooltransformcenter)
       This API member is considered internal to the library, as it is not likely to be of
       interest to the application programmer.
       Set a new center point during traversal.

   SbBool SoGetBoundingBoxAction::isCenterSet (void) const This API member is considered internal
       to the library, as it is not likely to be of interest to the application programmer.
       Query about the center point during traversal.

   void SoGetBoundingBoxAction::resetCenter (void) This API member is considered internal to the
       library, as it is not likely to be of interest to the application programmer.
       Reset the scene center point during traversal.

   void SoGetBoundingBoxAction::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 from SoAction.

Author

       Generated automatically by Doxygen for Coin from the source code.