XdkWrl: SpotLight Class Reference

6.64 SpotLight

The SpotLight node defines a light source that emits light from a specific point along a specific direction vector and constrained within a solid angle. Spotlights may illuminate geometry nodes that respond to light sources and intersect the solid angle defined by the SpotLight. Spotlight nodes are specified in the local coordinate system and are affected by ancestors' transformations.

A detailed description of ambientIntensity, color, intensity, and VRML's lighting equations is provided in 4.6.6, Light sources. More information on lighting concepts can be found in 4.14, Lighting model, including a detailed description of the VRML lighting equations.

The location field specifies a translation offset of the centre point of the light source from the light's local coordinate system origin. This point is the apex of the solid angle which bounds light emission from the given light source. The direction field specifies the direction vector of the light's central axis defined in the local coordinate system.

The on field specifies whether the light source emits light. If on is TRUE, the light source is emitting light and may illuminate geometry in the scene. If on is FALSE, the light source does not emit light and does not illuminate any geometry.

The radius field specifies the radial extent of the solid angle and the maximum distance from location that may be illuminated by the light source. The light source does not emit light outside this radius. The radius shall be greater than or equal to zero.

Both radius and location are affected by ancestors' transformations (scales affect radius and transformations affect location).

The cutOffAngle field specifies the outer bound of the solid angle. The light source does not emit light outside of this solid angle. The beamWidth field specifies an inner solid angle in which the light source emits light at uniform full intensity. The light source's emission intensity drops off from the inner solid angle (beamWidth) to the outer solid angle (cutOffAngle) as described in the following equations:

    angle = the angle between the Spotlight's direction vector
            and the vector from the Spotlight location to the point
            to be illuminated

    if (angle >= cutOffAngle):
        multiplier = 0
    else if (angle <= beamWidth):
        multiplier = 1
    else:
        multiplier = (angle - cutOffAngle) / (beamWidth - cutOffAngle)

    intensity(angle) = SpotLight.intensity × multiplier

If the beamWidth is greater than the cutOffAngle, beamWidth is defined to be equal to the cutOffAngle and the light source emits full intensity within the entire solid angle defined by cutOffAngle. Both beamWidth and cutOffAngle shall be greater than 0.0 and less than or equal to /2. Figure 6.16 depicts the beamWidth, cutOffAngle, direction, location, and radius fields of the SpotLight node.

Figure 6.16 -- SpotLight node

SpotLight illumination falls off with distance as specified by three attenuation coefficients. The attenuation factor is 1/max(attenuation[0] + attenuation[1]×r + attenuation[2]×r² , 1), where r is the distance from the light to the surface being illuminated. The default is no attenuation. An attenuation value of (0, 0, 0) is identical to (1, 0, 0). Attenuation values shall be greater than or equal to zero. A detailed description of VRML's lighting equations is contained in 4.14, Lighting model.

Constructor & Destructor Documentation

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_ambientIntensity
set_attenuation
set_beamWidth
set_color
set_cutOffAngle
set_direction
set_intensity
set_location
set_on
set_radius

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 : ambientIntensity_changed
1 : attenuation_changed
2 : beamWidth_changed
3 : color_changed
4 : cutOffAngle_changed
5 : direction_changed
6 : intensity_changed
7 : location_changed
8 : on_changed
9 : radius_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:

ambientIntensity_changed
attenuation_changed
beamWidth_changed
color_changed
cutOffAngle_changed
direction_changed
intensity_changed
location_changed
on_changed
radius_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 : ambientIntensity
1 : attenuation
2 : beamWidth
3 : color
4 : cutOffAngle
5 : direction
6 : intensity
7 : location
8 : on
9 : radius 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:

ambientIntensity
attenuation
beamWidth
color
cutOffAngle
direction
intensity
location
on
radius

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 "SpotLight". Useful for printing.

Implements Node.


Public Member Functions
	SpotLight (const char *name="")
virtual	~SpotLight ()
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.
SFFloat	ambientIntensity
SFVec3f	attenuation
SFFloat	beamWidth
SFColor	color
SFFloat	cutOffAngle
SFVec3f	direction
SFFloat	intensity
SFVec3f	location
SFBool	on
SFFloat	radius
Events In
EventIn< SFFloat >	set_ambientIntensity
EventIn< SFVec3f >	set_attenuation
EventIn< SFFloat >	set_beamWidth
EventIn< SFColor >	set_color
EventIn< SFFloat >	set_cutOffAngle
EventIn< SFVec3f >	set_direction
EventIn< SFFloat >	set_intensity
EventIn< SFVec3f >	set_location
EventIn< SFBool >	set_on
EventIn< SFFloat >	set_radius
Events Out
EventOut< SFFloat >	ambientIntensity_changed
EventOut< SFVec3f >	attenuation_changed
EventOut< SFFloat >	beamWidth_changed
EventOut< SFColor >	color_changed
EventOut< SFFloat >	cutOffAngle_changed
EventOut< SFVec3f >	direction_changed
EventOut< SFFloat >	intensity_changed
EventOut< SFVec3f >	location_changed
EventOut< SFBool >	on_changed
EventOut< SFFloat >	radius_changed

SpotLight Class Reference
[Standard Node Types]

Public Member Functions

Public Attributes

Detailed Description

6.64 SpotLight

Figure 6.16 -- SpotLight node

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

SpotLight Class Reference [Standard Node Types]

Public Member Functions

Public Attributes

Detailed Description

6.64 SpotLight

Figure 6.16 -- SpotLight node

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

SpotLight Class Reference
[Standard Node Types]