IfcSpotLightSource

IfcSpotLightSource

Definition from IAI: Spotlight is a light source that emits light from a specified location in a spefified direction, forming a cone. The light may attenuate with distance, and it may have a cut-off radius.

HISTORY New Entity in IFC 2x.
ISSUE See issue and change log for changes made in IFC 2x.

EXPRESS specification:

ENTITY IfcSpotLightSource

SUBTYPE OF (

IfcPointLightSource);

SpreadAngle

IfcPositivePlaneAngleMeasure;

CutOffAngle

IfcPositivePlaneAngleMeasure;

Radius

OPTIONAL IfcPositiveLengthMeasure;

Direction

IfcDirection;

WHERE

WR31	:	(SpreadAngle <= CutOffAngle) AND (SpreadAngle < 180.);
WR32	:	(CutOffAngle <= 180.);

END_ENTITY;

Attribute definitions:

SpreadAngle	:	Positive plane angle in degrees defining half-cone of the beam (on both sides of direction vector) where intensity of light is uniform.
CutOffAngle	:	Light intensity drops off between spread angle (defining the uniform intensity light beam) and cut-off angle.
Radius	:	Optional cut-off distance for the light emitted from the source.
Direction	:	Direction of the ligth in the WCS defined by the related geometric represenation context.

Formal Propositions:

WR31	:	SpreadAngle shall not be greater than CutOffAngle. Also, SpreadAngle shall be less than 180 degrees.
WR32	:	CutOffAngle shall not be greater than 180 degrees.