SoRayPickAction(3)

NAME
SoRayPickAction - The SoRayPickAction class does ray intersection with scene graphs.

SYNOPSIS

#include <Inventor/actions/SoRayPickAction.h>

Inherits SoPickAction.

  Public Member Functions
virtual SoType getTypeId (void) const
SoRayPickAction (const SbViewportRegion &viewportregion)
virtual ~SoRayPickAction ()
void setPoint (const SbVec2s &viewportPoint)
void setNormalizedPoint (const SbVec2f &normpoint)
void setRadius (const float radiusinpixels)
float getRadius (void) const
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, SbBool frontpick=TRUE)
void reset (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 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 mouse cursor upon mouse clicks, it also contains convenience methods for setting up a ray from the near plane to the far plane from the 2D mouse cursor 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 ray pick action to intersect from a point under the mouse cursor after a mouse click is that one tries to apply it to a scene graph that does not contain a camera explicitly set up by the application programmer. Without a camera as part of the traversal, the ray pick 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 scene graph, not the 'real' internal scene graph root used by the viewer (which should always contain a camera node). So ray picks done from the application code will fail when doing this:

// initializing viewer scene graph
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 ray pick 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 scene graph"

While this is the correct way to do it:

// initializing viewer scene graph
SoSeparator * root = new SoSeparator;
root->ref();
// Need to set up our own camera in the "user scene graph", or else
// the ray pick action will fail because the camera is hidden in the
// viewer-specific root of the scene graph.
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 ray pick 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' scene graph by simply calling:

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

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. For an in-depth explanation of why the viewportregion argument is needed, see the documentation of SoGetBoundingBox::SoGetBoundingBox(const SbViewportRegion &).

  SoRayPickAction::~SoRayPickAction (void) [virtual]
Destructor, free temporary resources used by action.

Member Function Documentation

  SoType SoRayPickAction::getTypeId (void) const [virtual]
Returns the type identification of an object derived from a class inheriting SoAction. This is used for runtime type checking and 'downward' casting.

Reimplemented from SoPickAction.

  SoType SoRayPickAction::getClassTypeId (void) [static]
This static method returns the SoType object associated with objects of this class.

  void SoRayPickAction::addMethod (const SoType type, SoActionMethod method) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoRayPickAction::enableElement (const SoType type, const int stackindex) [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 & SoRayPickAction::getEnabledElements (void) const [protected], [virtual]
Returns list of enabled elements.

Reimplemented from SoPickAction.

  SoEnabledElementsList * SoRayPickAction::getClassEnabledElements (void) [static], [protected]
Returns list of enabled elements for this class. The enabledElements and methods variables are protected in the original OIV API. This is not such a good idea, since exposed static class member variables is a major grievance with regard to Win32 DLLs. This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

  SoActionMethodList * SoRayPickAction::getClassActionMethods (void) [static], [protected]
Returns list of action methods for this class. The enabledElements and methods variables are protected in the original OIV API. This is not such a good idea, since exposed static class member variables is a major grievance with regard to Win32 DLLs. This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

  void SoRayPickAction::initClass (void) [static]
Initializes the runtime type system for this class, and sets up the enabled elements and action method list.

  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.

The radius of the intersection ray will only influence the pick operation's behavior versus lines and points, and has no effect on picking of shapes / polygons.

  float SoRayPickAction::getRadius (void) const
Gets the radius of the picking ray, in screen pixels.

  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 mouse cursor position upon clicks and scene graph camera settings.

  void SoRayPickAction::setPickAll (const SbBool flag)
Lets you decide whether or not all the objects the ray intersects with should be picked. If not, only the intersection point of the object closest to the camera will 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.

See also
    setPickAll()

  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 ray pick action.

  void SoRayPickAction::computeWorldSpaceRay (void)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::hasWorldSpaceRay (void) const
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoRayPickAction::setObjectSpace (void)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoRayPickAction::setObjectSpace (const SbMatrix & matrix)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::intersect (const SbVec3f & v0_in, const SbVec3f & v1_in, const SbVec3f & v2_in, SbVec3f & intersection, SbVec3f & barycentric, SbBool & front) const
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::intersect (const SbVec3f & v0_in, const SbVec3f & v1_in, SbVec3f & intersection) const
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::intersect (const SbVec3f & point_in) const
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::intersect (const SbBox3f & box, const SbBool usefullviewvolume = TRUE)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::intersect (const SbBox3f & box, SbVec3f & intersection, const SbBool usefullviewvolume = TRUE)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  const SbViewVolume & SoRayPickAction::getViewVolume (void)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  const SbLine & SoRayPickAction::getLine (void)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoRayPickAction::isBetweenPlanes (const SbVec3f & intersection_in) const
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoPickedPoint * SoRayPickAction::addIntersection (const SbVec3f & objectspacepoint_in, SbBool frontpick = TRUE)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoRayPickAction::reset (void)
Truncates the internal picked points list.

Since
    Coin 2.2

  void SoRayPickAction::beginTraversal (SoNode * node) [protected], [virtual]
This virtual method is called from SoAction::apply(), and is the entry point for the actual scene graph 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 scene graph traversal.

Reimplemented from SoPickAction.

Author

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