trusty (3) SoGetBoundingBoxAction.3.gz
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
virtual SoType getTypeId (void) const
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 ¢er, const SbBool transformcenter)
SbBool isCenterSet (void) const
void resetCenter (void)
Static Public Member Functions
static SoType getClassTypeId (void)
static void addMethod (const SoType type, SoActionMethod method)
static void enableElement (const SoType type, const int stackindex)
static void initClass (void)
Protected Member Functions
virtual const
SoEnabledElementsList & getEnabledElements (void) const "
virtual void beginTraversal (SoNode *node)
Static Protected Member Functions
static SoEnabledElementsList * getClassEnabledElements (void)
static SoActionMethodList * getClassActionMethods (void)
Additional Inherited Members
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
SoType SoGetBoundingBoxAction::getTypeId (void) const [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.
Implements SoAction.
void SoGetBoundingBoxAction::addMethod (const SoTypetype, SoActionMethodmethod) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the
application programmer.
void SoGetBoundingBoxAction::enableElement (const SoTypetype, const intstackindex) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the
application programmer.
const SoEnabledElementsList & SoGetBoundingBoxAction::getEnabledElements (void) const [protected], [virtual]
Returns a list of the elements used by action instances of this class upon traversal operations.
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 ¢erarg, 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
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