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SoVRMLBillboard Class Reference
[VRML97 classes]

The SoVRMLBillboard class is used for rotating geometry towards the viewpoint.

The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is copyright The Web3D Consortium, and is used by permission of the Consortium:. More...

#include <Inventor/VRMLnodes/SoVRMLBillboard.h>

Inheritance diagram for SoVRMLBillboard:

SoVRMLParent SoGroup SoNode SoFieldContainer SoBase

List of all members.

Public Member Functions

virtual SoType getTypeId (void) const
 SoVRMLBillboard (void)
 SoVRMLBillboard (int numchildren)
virtual void doAction (SoAction *action)
virtual void callback (SoCallbackAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void getMatrix (SoGetMatrixAction *action)
virtual void pick (SoPickAction *action)
virtual void search (SoSearchAction *action)
virtual void GLRenderBelowPath (SoGLRenderAction *action)
virtual void GLRenderInPath (SoGLRenderAction *action)
virtual void GLRenderOffPath (SoGLRenderAction *action)
virtual void notify (SoNotList *list)

Static Public Member Functions

static SoType getClassTypeId (void)
static void initClass (void)

Public Attributes

SoSFVec3f axisOfRotation
SoSFVec3f bboxCenter
SoSFVec3f bboxSize

Protected Member Functions

virtual const SoFieldDatagetFieldData (void) const
virtual ~SoVRMLBillboard ()

Static Protected Member Functions

static const SoFieldData ** getFieldDataPtr (void)


Detailed Description

The SoVRMLBillboard class is used for rotating geometry towards the viewpoint.

The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is copyright The Web3D Consortium, and is used by permission of the Consortium:.

  Billboard {
    eventIn      MFNode   addChildren
    eventIn      MFNode   removeChildren
    exposedField SFVec3f  axisOfRotation 0 1 0     # (-inf, inf)
    exposedField MFNode   children       []
    field        SFVec3f  bboxCenter     0 0 0     # (-inf, inf)
    field        SFVec3f  bboxSize       -1 -1 -1  # (0, inf) or -1,-1,-1
  }
  

The Billboard node is a grouping node which modifies its coordinate system so that the Billboard node's local Z-axis turns to point at the viewer. The Billboard node has children which may be other children nodes. The axisOfRotation field specifies which axis to use to perform the rotation. This axis is defined in the local coordinate system. When the axisOfRotation field is not (0, 0, 0), the following steps describe how to rotate the billboard to face the viewer:

When the axisOfRotation field is set to (0, 0, 0), the special case of viewer-alignment is indicated. In this case, the object rotates to keep the billboard's local Y-axis parallel with the Y-axis of the viewer. This special case is distinguished by setting the axisOfRotation to (0, 0, 0). The following steps describe how to align the billboard's Y-axis to the Y-axis of the viewer:

If the axisOfRotation and the billboard-to-viewer line are coincident, the plane cannot be established and the resulting rotation of the billboard is undefined. For example, if the axisOfRotation is set to (0,1,0) (Y-axis) and the viewer flies over the billboard and peers directly down the Y-axis, the results are undefined. Multiple instances of Billboard nodes (DEF/USE) operate as expected: each instance rotates in its unique coordinate system to face the viewer. Subclause 4.6.5, Grouping and children nodes (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-VRML97/part1/concepts.html#4.6.5>), provides a description of the children, addChildren, and removeChildren fields and eventIns. The bboxCenter and bboxSize fields specify a bounding box that encloses the Billboard node's children. This is a hint that may be used for optimization purposes. The results are undefined if the specified bounding box is smaller than the actual bounding box of the children at any time. A default bboxSize value, (-1, -1, -1), implies that the bounding box is not specified and if needed shall be calculated by the browser. A description of the bboxCenter and bboxSize fields is contained in 4.6.4, Bounding boxes (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-VRML97/part1/concepts.html#4.6.4>),

The rest of this class documentation is not from the VRML97 standards documentation, but was written specifically for the Coin3D API documentation.

The following example VRML scene is a simple illustration of how SoVRMLBillboard::axisOfRotation constrains rotation around the given vector:

  #VRML V2.0 utf8
  
  Transform {
     translation -2 0 0
     children [
        Billboard {
  	 children [ Box { } ]
        }
     ]
  }
  
  Transform {
     translation 2 0 0
     children [
        Billboard {
  	 axisOfRotation 0 1 0
  	 children [ Box { } ]
        }
     ]
  }
  
  Transform {
     translation 0 -2 0
     children [ Box { size 10 0.1 10 } ]
  }
  

Constructor & Destructor Documentation

SoVRMLBillboard::SoVRMLBillboard ( void   ) 

Constructor.

References axisOfRotation, bboxCenter, and bboxSize.

SoVRMLBillboard::SoVRMLBillboard ( int  numchildren  ) 

Constructor. numchildren is the expected number of children.

SoVRMLBillboard::~SoVRMLBillboard (  )  [protected, virtual]

Destructor.


Member Function Documentation

SoType SoVRMLBillboard::getClassTypeId ( void   )  [static]

This static method returns the SoType object associated with objects of this class.

Reimplemented from SoVRMLParent.

SoType SoVRMLBillboard::getTypeId ( void   )  const [virtual]

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and "downward" casting.

Usage example:

  void foo(SoNode * node)
  {
    if (node->getTypeId() == SoFile::getClassTypeId()) {
      SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
    }
    else if (node->getTypeId().isOfType(SoGroup::getClassTypeId())) {
      SoGroup * group = (SoGroup *)node;  // safe downward cast, knows the type
    }
  }

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: 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 for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups.

Reimplemented from SoVRMLParent.

Referenced by GLRenderBelowPath().

const SoFieldData ** SoVRMLBillboard::getFieldDataPtr ( 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.

Reimplemented from SoVRMLParent.

const SoFieldData * SoVRMLBillboard::getFieldData ( void   )  const [protected, virtual]

Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoVRMLParent.

void SoVRMLBillboard::initClass ( void   )  [static]

Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.

Reimplemented from SoVRMLParent.

void SoVRMLBillboard::doAction ( SoAction action  )  [virtual]

This function performs the typical operation of a node for any action.

Reimplemented from SoVRMLParent.

References SoAction::getState(), SoState::pop(), and SoState::push().

Referenced by callback(), pick(), and search().

void SoVRMLBillboard::callback ( SoCallbackAction action  )  [virtual]

Action method for SoCallbackAction.

Simply updates the state according to how the node behaves for the render action, so the application programmer can use the SoCallbackAction for extracting information about the scene graph.

Reimplemented from SoGroup.

References doAction().

void SoVRMLBillboard::GLRender ( SoGLRenderAction action  )  [virtual]

Action method for the SoGLRenderAction.

This is called during rendering traversals. Nodes influencing the rendering state in any way or who wants to throw geometry primitives at OpenGL overrides this method.

Reimplemented from SoGroup.

References SoAction::getCurPathCode(), GLRenderBelowPath(), and GLRenderInPath().

void SoVRMLBillboard::getBoundingBox ( SoGetBoundingBoxAction action  )  [virtual]

Action method for the SoGetBoundingBoxAction.

Calculates bounding box and center coordinates for node and modifies the values of the action to encompass the bounding box for this node and to shift the center point for the scene more towards the one for this node.

Nodes influencing how geometry nodes calculates their bounding box also overrides this method to change the relevant state variables.

Reimplemented from SoGroup.

References SoAction::getState(), SoState::pop(), and SoState::push().

void SoVRMLBillboard::getMatrix ( SoGetMatrixAction action  )  [virtual]

Action method for SoGetMatrixAction.

Updates action by accumulating with the transformation matrix of this node (if any).

Reimplemented from SoGroup.

void SoVRMLBillboard::pick ( SoPickAction action  )  [virtual]

Action method for SoPickAction.

Does common processing for SoPickAction action instances.

Reimplemented from SoGroup.

References doAction().

void SoVRMLBillboard::search ( SoSearchAction action  )  [virtual]

Action method for SoSearchAction.

Compares the search criteria from the action to see if this node is a match. Searching is done by matching up all criteria set up in the SoSearchAction -- if any of the requested criteria is a miss, the search is not deemed successful for the node.

See also:
SoSearchAction

Reimplemented from SoVRMLParent.

References doAction(), and SoSearchAction::isFound().

void SoVRMLBillboard::GLRenderBelowPath ( SoGLRenderAction action  )  [virtual]

void SoVRMLBillboard::GLRenderInPath ( SoGLRenderAction action  )  [virtual]

void SoVRMLBillboard::GLRenderOffPath ( SoGLRenderAction action  )  [virtual]

Implements the SoAction::OFF_PATH traversal method for the rendering action.

Reimplemented from SoNode.

void SoVRMLBillboard::notify ( SoNotList l  )  [virtual]

Notifies all auditors for this instance when changes are made.

Reimplemented from SoVRMLParent.

References SoVRMLParent::notify().


Member Data Documentation

The axis of rotation for the geometry.

Referenced by SoVRMLBillboard().

The bounding box center hint. Default value is (0, 0, 0).

Referenced by SoVRMLBillboard().

The bounding box size hint. Default value is (-1, -1, -1).

Referenced by SoVRMLBillboard().


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

Copyright © 1998-2007 by Systems in Motion AS. All rights reserved.

Generated on Mon Feb 23 16:34:06 2009 for Coin by Doxygen. 1.5.8