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SoRayPickAction Class Reference

The SoRayPickAction class does ray intersection with scene graphs. More...

#include <Inventor/actions/SoRayPickAction.h>

Inheritance diagram for SoRayPickAction::

List of all members.

Public Methods
	SoRayPickAction (const SbViewportRegion &viewportregion)
virtual	~SoRayPickAction ()
void	setPoint (const SbVec2s &viewportPoint)
void	setNormalizedPoint (const SbVec2f &normpoint)
void	setRadius (const float radiusinpixels)
void	setRay (const SbVec3f &start, const SbVec3f &direction, float neardistance=-1.0, float fardistance=-1.0)
void	setPickAll (const SbBool flag)
SbBool	isPickAll (void) const
const SoPickedPointList &	getPickedPointList (void) const
SoPickedPoint *	getPickedPoint (const int index=0) const
void	computeWorldSpaceRay (void)
SbBool	hasWorldSpaceRay (void) const
void	setObjectSpace (void)
void	setObjectSpace (const SbMatrix &matrix)
SbBool	intersect (const SbVec3f &v0, const SbVec3f &v1, const SbVec3f &v2, SbVec3f &intersection, SbVec3f &barycentric, SbBool &front) const
SbBool	intersect (const SbVec3f &v0, const SbVec3f &v1, SbVec3f &intersection) const
SbBool	intersect (const SbVec3f &point) const
SbBool	intersect (const SbBox3f &box, const SbBool usefullviewvolume=TRUE)
SbBool	intersect (const SbBox3f &box, SbVec3f &intersection, const SbBool usefullviewvolume=TRUE)
const SbViewVolume &	getViewVolume (void)
const SbLine &	getLine (void)
SbBool	isBetweenPlanes (const SbVec3f &intersection) const
SoPickedPoint *	addIntersection (const SbVec3f &objectspacepoint)
Static Public Methods
void	initClass (void)
Protected Methods
virtual void	beginTraversal (SoNode *node)

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Detailed Description

The SoRayPickAction class does ray intersection with scene graphs.

For interaction with the scene graph geometry, it is necessary to be able to do intersection testing for rays. This functionality is provided by the SoRayPickAction class.

SoRayPickAction can be used to pass arbitrary rays through the scene for intersection detections, by using the setRay() method.

Because a very common operation is to check for intersections along the ray from the mousecursor upon mouseclicks, it also contains convenience methods for setting up a ray from the near plane to the far plane from the 2D mousecursor coordinates. See the setPoint() and setNormalizedPoint() methods. A simple usage example for this case is presented below.

Note that one common mistake when using a raypick action to intersect from a point under the mousecursor after a mouseclick is that one tries to apply it to a scenegraph that does not contain a camera explicitly set up by the application programmer. Without a camera as part of the traversal, the raypick action does not know which view volume to send the ray through.

In this regard, be aware that the getSceneGraph() call in the So*-libraries' viewer classes will return the root of the user-supplied scenegraph, not the "real" internal scenegraph root used by the viewer (which should always contain a camera node). So raypicks done from the application code will fail when doing this:

  // initializing viewer scenegraph
  SoSeparator * root = new SoSeparator;
  root->ref();

  SoEventCallback * ecb = new SoEventCallback;
  ecb->addEventCallback(SoMouseButtonEvent::getClassTypeId(), event_cb, viewer);
  root->addChild(ecb);

  root->addChild(new SoCone);
  
  viewer->setSceneGraph( root );
  // -- [snip] -------------------------

  // attempting raypick in the event_cb() callback method
  SoRayPickAction rp( viewer->getViewportRegion() );
  rp.setPoint(mouseevent->getPosition());
  rp.apply(viewer->getSceneGraph());
  // BUG: results will not be what you expected, as no camera was
  // part of the "user's scenegraph"

While this is the correct way to do it:

  // initializing viewer scenegraph
  SoSeparator * root = new SoSeparator;
  root->ref();

  // Need to set up our own camera in the "user scenegraph", or else
  // the raypick action will fail because the camera is hidden in the
  // viewer-specific root of the scenegraph.
  SoPerspectiveCamera * pcam = new SoPerspectiveCamera;
  root->addChild(pcam);

  SoEventCallback * ecb = new SoEventCallback;
  ecb->addEventCallback(SoMouseButtonEvent::getClassTypeId(), event_cb, viewer);
  root->addChild(ecb);

  root->addChild(new SoCone);
  
  viewer->setSceneGraph( root );
  pcam->viewAll( root, viewer->getViewportRegion() );
  // -- [snip] -------------------------

  // attempting raypick in the event_cb() callback method
  SoRayPickAction rp( viewer->getViewportRegion() );
  rp.setPoint(mouseevent->getPosition());
  rp.apply(viewer->getSceneGraph());

Or if you do want the convenience of having the viewer set up a camera for you implicitly, you can get hold of the root-node of the "complete" scenegraph by simply calling:

  SoNode * realroot = viewer->getSceneManager()->getSceneGraph();

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Constructor & Destructor Documentation

SoRayPickAction::SoRayPickAction (  const SbViewportRegion & viewportregion )

Constructor. Some node types need a viewportregion to know exactly how they are positioned within the scene.

SoRayPickAction::~SoRayPickAction (  void )  [virtual]

Destructor, free temporary resources used by action.

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Member Function Documentation

void SoRayPickAction::initClass (  void )  [static]

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

void SoRayPickAction::setPoint (  const SbVec2s & viewportpoint )

Sets the viewport-space point. This point is calculated into a line from the near clipping plane to the far clipping plane, and the intersection ray follows the line. This is a convenient way to detect object intersection below the cursor.

void SoRayPickAction::setNormalizedPoint (  const SbVec2f & normpoint )

Sets the viewport-space point which the ray is sent through. The coordinate is normalized, ranging from (0, 0) to (1, 1). See also: setPoint()

void SoRayPickAction::setRadius (  const float radiusinpixels )

Sets the radius of the picking ray, in screen pixels. Default value is 5.0.

void SoRayPickAction::setRay (  const SbVec3f & start, const SbVec3f & direction, float neardistance = -1.0, float fardistance = -1.0 )

Sets the intersection ray in world-space coordinates. Use this method if you want to send any ray through the scene to detect intersections, independently of mouseposition and mouseclicks.

void SoRayPickAction::setPickAll (  const SbBool flag )

Lets you decide whether only the closest object or all the objects the ray intersects with should be picked. Default value of the "pick all" flag is FALSE.

SbBool SoRayPickAction::isPickAll (  void )  const

Returns whether only the closest object or all the objects the ray intersects with is picked.

const SoPickedPointList & SoRayPickAction::getPickedPointList (  void )  const

Returns a list of the picked points.

SoPickedPoint * SoRayPickAction::getPickedPoint (  const int index = 0 )  const

Returns the picked point with index in the list of picked points. Returns NULL if less than index + 1 points where picked during the last raypick action.

void SoRayPickAction::computeWorldSpaceRay (  void )

For internal use only.

SbBool SoRayPickAction::hasWorldSpaceRay (  void )  const

For internal use only.

void SoRayPickAction::setObjectSpace (  void )

For internal use only.

void SoRayPickAction::setObjectSpace (  const SbMatrix & matrix )

For internal use only.

SbBool SoRayPickAction::intersect (  const SbVec3f & v0, const SbVec3f & v1, const SbVec3f & v2, SbVec3f & intersection, SbVec3f & barycentric, SbBool & front )  const

For internal use only.

SbBool SoRayPickAction::intersect (  const SbVec3f & v0, const SbVec3f & v1, SbVec3f & intersection )  const

For internal use only.

SbBool SoRayPickAction::intersect (  const SbVec3f & point )  const

For internal use only.

SbBool SoRayPickAction::intersect (  const SbBox3f & box, const SbBool usefullviewvolume = TRUE )

For internal use only.

SbBool SoRayPickAction::intersect (  const SbBox3f & box, SbVec3f & intersection, const SbBool usefullviewvolume = TRUE )

For internal use only.

const SbViewVolume & SoRayPickAction::getViewVolume (  void )

For internal use only.

const SbLine & SoRayPickAction::getLine (  void )

For internal use only.

SbBool SoRayPickAction::isBetweenPlanes (  const SbVec3f & intersection )  const

For internal use only.

SoPickedPoint * SoRayPickAction::addIntersection (  const SbVec3f & objectspacepoint )

For internal use only.

void SoRayPickAction::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 SoPickAction.

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The documentation for this class was generated from the following files:

• SoRayPickAction.cpp
• SoRayPickAction.h

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