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SoField(3IV)()							SoField(3IV)()

NAME
       SoField -- base class for all fields

INHERITS FROM
       SoField

SYNOPSIS
       #include	<Inventor/fields/SoField.h>

	  Methods from class SoField:

     void		 setIgnored(SbBool ignore)
     SbBool		 isIgnored() const
     SbBool		 isDefault() const
     static SoType	 getClassTypeId()
     virtual SoType	 getTypeId() const
     virtual SbBool	 isOfType(SoType type) const
     SbBool		 set(const char	*valueString)
     void		 get(SbString &valueString)
     int		 operator ==(const SoField &f) const
     int		 operator !=(const SoField &f) const
     void		 touch()
     SbBool		 connectFrom(SoField *fromField)
     SbBool		 connectFrom(SoEngineOutput *fromEngine)
     void		 disconnect()
     SbBool		 isConnected() const
     SbBool		 isConnectedFromField()	const
     SbBool		 getConnectedField(SoField *&writingField) const
     SbBool		 isConnectedFromEngine() const
     SbBool		 getConnectedEngine(SoEngineOutput     *&engineOutput)
			      const
     void		 enableConnection(SbBool flag)
     SbBool		 isConnectionEnabled() const
     int		 getForwardConnections(SoFieldList &list) const
     SoFieldContainer *	 getContainer()	const

DESCRIPTION
       SoField is the abstract base class for all fields. Fields are the  data
       elements	 contained  within nodes and are the input values for engines.
       Each node or engine class specifies a set of fields  and	 associates  a
       name  with  each.  These	names define the semantics of the field	(e.g.,
       the SoCube node contains	three float fields named  width,  height,  and
       depth).	Field classes provide the access methods that indirectly allow
       editing and querying of data within nodes.

       There are two abstract subclasses of  SoField:  SoSField	 is  the  base
       class  for  all	single-valued  field  classes and SoMField is the base
       class for all multiple-valued fields, which contain dynamic  arrays  of
       values.	Subclasses  of SoSField	have an	SoSF prefix, and subclasses of
       SoMField	have an	SoMF prefix. See the reference pages for SoSField  and
       SoMField	for additional methods.

       Fields  are typically constructed only within node or engine instances;
       if you need a field that	is not part of a node or engine, you can  cre-
       ate a GlobalField; see the methods on SoDB for creating global fields.

       Fields  can  be	connected  either directly to another field, or	can be
       connected to the	output of an engine. The value of a field with a  con-
       nection	will change when the thing it is connected to changes. For ex-
       ample, consider a field "A" that	is connected from "B" (by  A->connect-
       From(B)).  When	B's value is changed, A's value	will also change. Note
       that A and B may	have different values, even if they are	connected:  if
       A's  value is set after B's value, A's value will be different from B's
       until B's value is set.

       A field can be connected	to several other fields, but can be  connected
       from only one source.

       It  is possible (and often useful) to create loops of field connections
       (for example, A connected from B	and B connected	from A). If there  are
       loops,  then  the  rule	is that	the last setValue() done overrides any
       connections in to that value. You can think of setting the value	 of  a
       field as	immediately propagating	that value forward into	all the	fields
       it is connected to, with	the propagation	stopping at  the  place	 where
       the  original setValue()	occurred if there is a connection loop.	(Actu-
       ally, a more efficient mechanism	than this is used, but	the  semantics
       are the same.)

       If  you try to connect two fields of differing types, Inventor will au-
       tomatically try to insert a field converter engine between them to con-
       vert  values from one type into the other. Inventor has most reasonable
       conversions built-in (multiple-valued field to single-valued  and  vice
       versa, anything to SoSFString, anything to SoSFTrigger, float/short/un-
       signed short/int32_t/uint32_t/etc numeric conversions,  etc).  You  can
       add  field  converters using SoDB's extender method addConverter(); see
       the SoDB.h header file for details. You can also	find  out  if  a  con-
       verter is available with	the SoDB::getConverter() method.

       Fields  each define their own file format for reading and being written
       to files, but all fields	follow the same	conventions:

       Fields in a node	or engine are written as the name of  the  field  fol-
       lowed  by  the  field's	value; fields are not written if they have not
       been modified since they	were  created  (if  they  have	their  default
       value).

       The  ignored flag is written as a "~" character after the field's value
       (if the field's value is	its default value, just	the "~"	is written).

       Field connections are written as	an "=" followed	by  the	 container  of
       the  field or engine output that	the field is connected to, followed by
       a "." and the name of the field or engine output. For example:

	  DEF node1 Transform {	translation 1 1	1 }
	  DEF node2 Scale { scaleFactor	1 1 1 =	USE node1.translation }

     Global fields are written as part of an internal  SoFieldContainer	 class
     called  GlobalField,  which writes	out an SoSFName	field named type whose
     value is the type of the global field, followed by	a field	of  that  type
     whose  name  is  the  name	 of  the  global  field. For example, a	global
     uint32_t field called "FrameCounter" whose	value is 494 would be  written
     as:

	  GlobalField {
			      type SoSFUInt32
			      FrameCounter 494
	  }

METHODS
     void		 setIgnored(SbBool ignore)
     SbBool		 isIgnored() const
	  Sets/gets the	ignore flag for	this field. When a field's ignore flag
	  is set to TRUE, the field is not used	during traversal for rendering
	  and other actions. The default value for this	flag is	FALSE.

     SbBool		 isDefault() const
	  Gets	the state of default flag of the field.	This flag will be TRUE
	  for any field	whose value is not  modified  after  construction  and
	  will	be  FALSE for those that have changed (each node or engine de-
	  termines what	the default values for	its  fields  are).  Note:  the
	  state	of this	flag should not	be set explicitly from within applica-
	  tions.

     static SoType	 getClassTypeId()
	  Return the type identifier for this field class.

     virtual SoType	 getTypeId() const
	  Return the type identifier for this field instance (SoField *).

     virtual SbBool	 isOfType(SoType type) const
	  Returns TRUE if this field is	the given type or  derived  from  that
	  type.	This is	typically used with the	getClassTypeId() method	to de-
	  termine the type of an SoField * at run-time:

	       SoField *field =	....;
	       if (field->isOfType(SoSFFloat::getClassTypeId())) {
		   SoSFFloat *floatField = (SoSFFloat *)field);
		   floatField->setValue(4.5);
	       }

     SbBool		 set(const char	*valueString)
	  Sets the field to the	given value, which is an ASCII string  in  the
	  Inventor  file format. Each field subclass defines its own file for-
	  mat; see their reference pages for information on their file format.
	  The  string  should  contain only the	field's	value, not the field's
	  name (e.g., "1.0", not "width	1.0"). This method returns TRUE	if the
	  string is valid, FALSE if it is not.

     void		 get(SbString &valueString)
	  Returns  the value of	the field in the Inventor file format, even if
	  the field has	its default value.

     int		 operator ==(const SoField &f) const
     int		 operator !=(const SoField &f) const
	  Return TRUE (FALSE) if this field is of the same type	 and  has  the
	  same value as	f.

     void		 touch()
	  Simulates  a	change to the field, causing attached sensors to fire,
	  connected fields and engines to be marked as needing evaluation, and
	  so forth. Calling touch() on an instance of a	derived	field class is
	  equivalent to	calling	setValue(getValue()) using the derived class's
	  methods,  except  that  the  field's	isDefault() status remains un-
	  changed.

     SbBool		 connectFrom(SoField *fromField)
     SbBool		 connectFrom(SoEngineOutput *fromEngine)
	  Connects this	field to another field or from an  engine  output.  If
	  the  field  was  connected to	something before, it will be automati-
	  cally	disconnected (a	field may have	only  one  connection  writing
	  into	it  at	a  time). Unless connections to	the field are disabled
	  (see enableConnection()), the	field's	value will be set to the value
	  of the thing it is connected to.

     void		 disconnect()
	  Disconnect  the  field  from whatever	it was connected to. This does
	  nothing if the field was not connected.

     SbBool		 isConnected() const
	  Returns TRUE if the field is connected to anything.

     SbBool		 isConnectedFromField()	const
	  Returns TRUE if the field is connected to another field.

     SbBool		 getConnectedField(SoField *&writingField) const
	  Returns TRUE if this field is	being written into by  another	field,
	  and  returns	the  field it is connected to in writingField. Returns
	  FALSE	and does not modify writingField if it is not connected	 to  a
	  field.

     SbBool		 isConnectedFromEngine() const
	  Returns TRUE if the field is connected to an engine's	output.

     SbBool		 getConnectedEngine(SoEngineOutput     *&engineOutput)
			      const
	  Returns TRUE if this field is	being written into by an  engine,  and
	  returns  the	engine	output it is connected to in engineOutput. Re-
	  turns	FALSE and does not modify engineOutput if it is	not  connected
	  to an	engine.

     void		 enableConnection(SbBool flag)
	  Field	 connections  may be enabled and disabled. Disabling a field's
	  connection is	almost exactly like disconnecting it; the only differ-
	  ence	is  that you can later re-enable the connection	by calling en-
	  ableConnection(TRUE).	 Note that disconnecting an engine output  can
	  cause	 the engine's reference	count to be decremented	and the	engine
	  to be	deleted, but disabling the connection does not	decrement  its
	  reference count.

	  Re-enabling  a  connection  will  cause the value of the field to be
	  changed to the engine	output or field	to which it is connected.

	  A field's connection-enabled status is maintained even if the	 field
	  is disconnected or reconnected. By default, connections are enabled.

     SbBool		 isConnectionEnabled() const
	  Returns  FALSE  if connections to this field are disabled. Note that
	  this may return FALSE	even if	the field is  not  connected  to  any-
	  thing.

     int		 getForwardConnections(SoFieldList &list) const
	  Adds	pointers  to all of the	fields that this field is writing into
	  (either fields in nodes, global fields  or  engine  inputs)  to  the
	  given	field list, and	returns	the number of forward connections.

     SoFieldContainer *	 getContainer()	const
	  Returns  the object that contains this field.	The type of the	object
	  will be either SoNode, SoEngine, or will be a	global field container
	  (note	that the global	field container	class is internal to Inventor;
	  see the methods for creating and accessing global fields  on	SoDB).
	  For example:

	       SoFieldContainer	*f = field->getContainer();
	       if (f->isOfType(SoNode::getClassTypeId())) {
		    ...	do something ...
	       } else if (f->isOfType(SoEngine::getClassTypeId())) {
		    ...	do someting else ...
	       } else {
		    ...	it must	be a global field.  We can figure out its name,	but
				   that	is about it:
		    const SbName &globalFieldName = f->getName();
	       }

SEE ALSO
       SoSField, SoMField, SoNode, SoDB

								SoField(3IV)()

NAME | INHERITS FROM | SYNOPSIS | DESCRIPTION | METHODS | SEE ALSO

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