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LOD Class Reference
[Standard Node Types]

#include <lod.h>

Inherits Node.

Inheritance diagram for LOD:

Inheritance graph
[legend]
List of all members.

Public Member Functions

 LOD (const char *name="")
virtual ~LOD ()
virtual unsigned int nbFields () const
virtual FieldHandle field (const std::string &n)
virtual FieldHandle field (const unsigned int i)
virtual bool isSetToDefaultValue (const unsigned int i) const
virtual unsigned int nbEventsIn () const
virtual EventInHandle eventIn (const std::string &n)
virtual EventInHandle eventIn (const unsigned int i)
virtual unsigned int nbEventsOut () const
virtual EventOutHandle eventOut (const std::string &n)
virtual EventOutHandle eventOut (const unsigned int i)
const char * typeName () const
virtual Node * duplicate () const
virtual Node * duplicate (std::map< const Node *, Node * > &) const

Public Attributes

Exposed Fields
A field that is capable of receiving events via an eventIn to change its value(s), and generating events via an eventOut when its value(s) change.

MFNode level
Fields
A property or attribute of a node. Each node type has a fixed set of fields. Fields may contain various kinds of data and one or many values. Each field has a default value.

SFVec3f center
MFFloat range
Events In
EventIn< MFNode > set_level
Events Out
EventOut< MFNode > level_changed

Detailed Description

Here is the documentation for this node type, from the ISO standard.

+6.38 LOD

The LOD node specifies various levels of detail or complexity for a given object, and provides hints allowing browsers to automatically choose the appropriate version of the object based on the distance from the user. The level field contains a list of nodes that represent the same object or objects at varying levels of detail, ordered from highest level of detail to the lowest level of detail. The range field specifies the ideal distances at which to switch between the levels. Subclause 4.6.5, Grouping and children nodes, contains details on the types of nodes that are legal values for level.

The center field is a translation offset in the local coordinate system that specifies the centre of the LOD node for distance calculations.

The number of nodes in the level field shall exceed the number of values in the range field by one (i.e., N+1 level values for N range values). The range field contains monotonic increasing values that shall be greater than zero. In order to calculate which level to display, first the distance is calculated from the viewer's location, transformed into the local coordinate system of the LOD node (including any scaling transformations), to the center point of the LOD node. Then, the LOD node evaluates the step function L(d) to choose a level for a given value of d (where d is the distance from the viewer position to the centre of the LOD node).

Let n ranges, R0, R1, R2, ..., Rn-1, partition the domain (0, +infinity) into n+1 subintervals given by (0, R0), [R0, R1)... , [Rn-1, +infinity). Also, let n levels L0, L1, L2, ..., Ln-1 be the values of the step function function L(d). The level node, L(d), for a given distance d is defined as follows:

    L(d) = L0,   if d < R0,
         = Li+1, if Ri <= d < Ri+1, for -1 < i < n-1,
         = Ln-1, if d >= Rn-1.

Specifying too few levels will result in the last level being used repeatedly for the lowest levels of detail. If more levels than ranges are specified, the extra levels are ignored. An empty range field is an exception to this rule. This case is a hint to the browser that it may choose a level automatically to maintain a constant display rate. Each value in the range field shall be greater than the previous value.

LOD nodes are evaluated top-down in the scene graph. Only the descendants of the currently selected level are rendered. All nodes under an LOD node continue to receive and send events regardless of which LOD node's level is active. For example, if an active TimeSensor node is contained within an inactive level of an LOD node, the TimeSensor node sends events regardless of the LOD node's state.

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Constructor & Destructor Documentation

LOD (  const char *  name = ""  ) 
 

Construct a node with all its fields set to default value, which is equivalent to the code below: 

  center.setXYZ(0,0,0);

~LOD (   )  [virtual]
 

Virtual destructor, does nothing

Member Function Documentation

wrl::Node * duplicate (  std::map< const Node *, Node * > &   )  const [virtual]
 

Implements Node.

wrl::Node * duplicate (   )  const [virtual]
 

Returns a deep copy of this node, that is a fully independant node with all children (if any) also copied. This is mainly useful for instanciating protos.

Implements Node.

wrl::Node::EventInHandle eventIn (  const unsigned int  n  )  [virtual]
 

Return a handle on the i th event in of the node or a "unknown" typed handle if there is no such node. emarks This class has no eventIn. This function is useful, with nbEventsIn() if you want to traverse all events in of a Node.

Implements Node.

wrl::Node::EventInHandle eventIn (  const std::string &  n  )  [virtual]
 

Return a handle on the event in named n of the node or a "unknown" typed handle if there is no such event. Valid names are:

  • set_level

Implements Node.

wrl::Node::EventOutHandle eventOut (  const unsigned int  n  )  [virtual]
 

Return a handle on the i th event out of the node or a "unknown" typed handle if there is no such node. Here is how i is related to fields:

  • 0 : level_changed This function is useful, with nbEventsOut() if you want to traverse all events in of a Node.

Implements Node.

wrl::Node::EventOutHandle eventOut (  const std::string &  n  )  [virtual]
 

Return a handle on the event out named n of the node or a "unknown" typed handle if there is no such event. Valid names are:

  • level_changed

Implements Node.

wrl::Node::FieldHandle field (  const unsigned int  n  )  [virtual]
 

Return a handle on the i th field of the node or a "unknown" typed handle if there is no such node. Here is how i is related to fields:

  • 0 : level
  • 1 : center
  • 2 : range This function is useful, with nbFields() if you want to traverse all fields of a Node.

Implements Node.

wrl::Node::FieldHandle field (  const std::string &  n  )  [virtual]
 

Return a handle on the field named n of the node or a "unknown" typed handle if there is no such field. Valid names are:

  • level
  • center
  • range

Implements Node.

bool isSetToDefaultValue (  const unsigned int  i  )  const [virtual]
 

Implements Node.

unsigned int nbEventsIn (   )  const [inline, virtual]
 

Returns the number of events in for this node type.

Implements Node.

unsigned int nbEventsOut (   )  const [inline, virtual]
 

Returns the number of events out for this node type.

Implements Node.

unsigned int nbFields (   )  const [inline, virtual]
 

Returns the number of fields (exposed or not) for this node type.

Implements Node.

const char * typeName (   )  const [inline, virtual]
 

Returns "LOD". Useful for printing.

Implements Node.

Member Data Documentation

SFVec3f center
 

See Detailed Description for meaning of this field. Default value is set to 

       center.setXYZ(0,0,0);

MFNode level
 

See Detailed Description for meaning of this field. Default value is set to MFNode default value

EventOut<MFNode> level_changed
 

Changed event associated to exposedField level

MFFloat range
 

See Detailed Description for meaning of this field. Default value is set to MFFloat default value

EventIn<MFNode> set_level
 

Set event associated to exposedField level

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