SoSwitch(3)

NAME
SoSwitch - The SoSwitch class is a group node which selects one child subgraph for traversal.

Which child to traverse is controlled by the application programmer by using the SoSwitch::whichChild field. In addition to picking out a single child for traversal, it is also possible to flip all children on or off for traversal.

SYNOPSIS

#include <Inventor/nodes/SoSwitch.h>

Inherits SoGroup.

Inherited by SoBlinker.

  Public Member Functions
virtual SoType getTypeId (void) const
SoSwitch (void)
SoSwitch (int numchildren)
virtual SbBool affectsState (void) const
virtual void doAction (SoAction *action)
virtual void callback (SoCallbackAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void pick (SoPickAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void handleEvent (SoHandleEventAction *action)
virtual void getMatrix (SoGetMatrixAction *action)
virtual void search (SoSearchAction *action)
virtual void write (SoWriteAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
virtual void audioRender (SoAudioRenderAction *action)
virtual void notify (SoNotList *nl)

  Static Public Member Functions
static SoType getClassTypeId (void)
static void initClass (void)

  Public Attributes
SoSFInt32 whichChild

  Protected Member Functions
virtual const SoFieldData * getFieldData (void) const
virtual ~SoSwitch ()
void traverseChildren (SoAction *action)

  Static Protected Member Functions
static const SoFieldData ** getFieldDataPtr (void)

  Additional Inherited Members

Detailed Description

The SoSwitch class is a group node which selects one child subgraph for traversal.

Which child to traverse is controlled by the application programmer by using the SoSwitch::whichChild field. In addition to picking out a single child for traversal, it is also possible to flip all children on or off for traversal. This node is very useful for conditionally turning on or off parts of the scenegraph based on the current application processing mode, visualizing mode, or whatever else the application can do.

FILE FORMAT/DEFAULTS:

Switch {
    whichChild -1
}

Constructor & Destructor Documentation

  SoSwitch::SoSwitch (void)
Default constructor.

  SoSwitch::SoSwitch (int numchildren)
Constructor.

The argument should be the approximate number of children which is expected to be inserted below this node. The number need not be exact, as it is only used as a hint for better memory resource allocation.

  SoSwitch::~SoSwitch () [protected], [virtual]
Destructor.

Member Function Documentation

  SoType SoSwitch::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
  }
}

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 SoGroup.

Reimplemented in SoBlinker.

  const SoFieldData * SoSwitch::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 SoGroup.

Reimplemented in SoBlinker.

  SbBool SoSwitch::affectsState (void) const [virtual]
Returns TRUE if the node could have any effect on the state during traversal.

If it returns FALSE, no data in the traversal-state will change from the pre-traversal state to the post-traversal state. The SoSeparator node will for instance return FALSE, as it pushes and pops the state before and after traversal of its children. All SoShape nodes will also return FALSE, as just pushing out geometry data to the rendering engine won't affect the actual rendering state.

The default method returns TRUE, on a 'better safe than sorry' philosophy.

Reimplemented from SoNode.

  void SoSwitch::doAction (SoAction * action) [virtual]
This function performs the typical operation of a node for any action.

Reimplemented from SoGroup.

  void SoSwitch::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.

  void SoSwitch::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.

  void SoSwitch::pick (SoPickAction * action) [virtual]
Action method for SoPickAction.

Does common processing for SoPickAction action instances.

Reimplemented from SoGroup.

  void SoSwitch::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.

Reimplemented in SoBlinker.

  void SoSwitch::handleEvent (SoHandleEventAction * action) [virtual]
Action method for SoHandleEventAction.

Inspects the event data from action, and processes it if it is something which this node should react to.

Nodes influencing relevant state variables for how event handling is done also overrides this method.

Reimplemented from SoGroup.

  void SoSwitch::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 SoSwitch::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 SoGroup.

  void SoSwitch::write (SoWriteAction * action) [virtual]
Action method for SoWriteAction.

Writes out a node object, and any connected nodes, engines etc, if necessary.

Reimplemented from SoGroup.

Reimplemented in SoBlinker.

  void SoSwitch::getPrimitiveCount (SoGetPrimitiveCountAction * action) [virtual]
Action method for the SoGetPrimitiveCountAction.

Calculates the number of triangle, line segment and point primitives for the node and adds these to the counters of the action.

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

Reimplemented from SoGroup.

  void SoSwitch::audioRender (SoAudioRenderAction * action) [virtual]
Action method for SoAudioRenderAction.

Does common processing for SoAudioRenderAction action instances.

Reimplemented from SoGroup.

  void SoSwitch::notify (SoNotList * l) [virtual]
Notifies all auditors for this instance when changes are made.

Reimplemented from SoNode.

Reimplemented in SoBlinker.

  void SoSwitch::traverseChildren (SoAction * action) [protected]
This function was part of the original SGI Inventor API, but it is not supported in Coin, as it looks like it should probably have been private in Inventor.

Member Data Documentation

  SoSFInt32 SoSwitch::whichChild
Selects which child to traverse during rendering (and some other) actions.

The value should be either SO_SWITCH_NONE (for traversing no children, like it was an empty SoGroup node), SO_SWITCH_ALL (for traversing like if we were an SoGroup node), SO_SWITCH_INHERIT (for traversing the same child as the last SoSwitch node), or an index value for a child.

When using SO_SWITCH_INHERIT, it is important to understand how the SoSwitch-node is affected by other SoSwitch-nodes. If you have several switches in the scenegraph, the last switch with its whichChild field set to anything but SO_SWITCH_INHERIT will be used. The switch does not only inherit from its parent switch node, but also from its siblings, located anywhere before it in the scenegraph. An example will help clarify this:

#Inventor V2.1 ascii
Separator {
  Switch {
    whichChild 0
    Group {
      Switch {
        whichChild 1
        BaseColor { rgb 1 0 0 } # red
        BaseColor { rgb 1 1 0 } # yellow
      }
      Switch {
        whichChild -2 # SO_SWITCH_INHERIT
        BaseColor { rgb 0 1 0 } # green
        BaseColor { rgb 0 0 1 } # blue
      }
      Cube { }
    }
  }
}

This results in a blue cube on the screen. The reason being that the value of the previous whichChild field was inherited by the final switch, making it select child 1 - the blue BaseColor.

When constructing ascii Inventor files, the integer values for the keywords must be used instead of their names. They are -1 for SO_SWITCH_NONE, -2 for SO_SWITCH_INHERIT, and -3 for SO_SWITCH_ALL.

Default value for the field is SO_SWITCH_NONE.

Author

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