The SoVRMLSpotLight node defines a light source that emits light from a specific point along a specific direction vector and constrained within a solid angle. SoVRMLSpotlights may illuminate geometry nodes that respond to light sources and intersect the solid angle. SoVRMLSpotlights are specified in their local coordinate system and are affected by parent transformations.

Note: SoVRMLSpotLights only illuminate objects in their enclosing parent group (similar to Directional lights). This is a slight deviation from the behavior described by the VRML97 specification.

<font color="#0000FF">NOTE:</font> This class does not exist in Open Inventor 10.0 and later.

VRML97 SPECIFICATION

This section describes the expected behavior of the node in a conforming VRML97 browser application. In some cases, the application is responsible for implementing portions of the expected behavior. Open Inventor viewer classes and IVF classes implement some of the application behaviors.

This section may reference portions of the VRML97 specification that are not present in this help file. The complete VRML97 spec is available at http://www.web3d.org.

The SoVRMLSpotLight node defines a light source that emits light from a specific point along a specific direction vector and constrained within a solid angle. SoVRMLSpotlights may illuminate geometry nodes that respond to light sources and intersect the solid angle. SoVRMLSpotlights are specified in their local coordinate system and are affected by parent transformations.

See "Concepts - Light Sources" for a detailed description of ambientIntensity , color , intensity , and VRML's lighting equations. See "Concepts - Lighting Model" for a detailed description of the VRML lighting equations.

The location field specifies a translation offset of the center 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 its own local coordinate system. The on field specifies whether the light source emits lightif true, then the light source is emitting light and may illuminate geometry in the scene, if false it 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 than may be illuminated by the light source - the light source does not emit light outside this radius. The radius must be >= 0.0.

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). The drop off function from the inner angle to the outer angle is a cosine raised to a power function:

   intensity(angle) = intensity * (cosine(angle) ** exponent)

  where exponent = 0.5*log(0.5)/log(cos(beamWidth)),
  intensity is the SpotLight's field value,
  intensity(angle) is the light intensity at an arbitrary
  angle from the direction vector,
  and angle ranges from 0.0 at central axis to cutOffAngle.

If beamWidth > cutOffAngle, then beamWidth is assumed to be equal to cutOffAngle and the light source emits full intensity within the entire solid angle defined by cutOffAngle. Both beamWidth and cutOffAngle must be greater than 0.0 and less than or equal to pi/2. See the figure below for an illustration of the SoVRMLSpotLight's field semantics (note: this example uses the default attenuation).

The light's illumination falls off with distance as specified by three attenuation coefficients. The attenuation factor is 1/( attenuation [0] + attenuation [1]*r + attenuation [2]*r^2) , where r is the distance of 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 must be >= 0.0.

FILE FORMAT/DEFAULT

VRMLSpotLight {

ambientIntensity	0
attenuation	1 0 0
beamWidth	1.570796
color	1 1 1
cutOffAngle	0.785398
direction	0 0 -1
intensity	1
location	0 0 0
on	true
radius	100
metadata	NULL

}

ACTION BEHAVIOR

SoGLRenderAction Sets: SoGLLightIdElement

EVENTS

eventIn

SoSFFloat	set_ambientIntensity
SoSFVec3f	set_attenuation
SoSFFloat	set_beamWidth
SoSFColor	set_color
SoSFFloat	set_cutOffAngle
SoSFVec3f	set_direction
SoSFFloat	set_intensity
SoSFVec3f	set_location
SoSFBool	set_on
SoSFFloat	set_radius (Note: Not implemented)
SoSFNode	set_metadata

eventOut

SoSFFloat	ambientIntensity_changed
SoSFVec3f	attenuation_changed
SoSFFloat	beamWidth_changed
SoSFColor	color_changed
SoSFFloat	cutOffAngle_changed
SoSFVec3f	direction_changed
SoSFFloat	intensity_changed
SoSFVec3f	location_changed
SoSFBool	on_changed
SoSFFloat	radius_changed (Note: Not implemented)
SoSFNode	metadata_changed

Obsoletesince Open Inventor 9500 The VRML API is no longer supported. See section http://oivdoc95.vsg3d.com/content/compatibility-notes-4#Deprecation of the Reference Manual.

Reference