# 8.14.3.7 IfcLightSourcePositional

## 8.14.3.7.1 Semantic definition

Point light node's illumination falls off with distance as specified by three attenuation coefficients. The attenuation factor is

1/max(attenuation[0] + attenuation[1] × r + attenuation[2] × r 2 , 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.

## 8.14.3.7.4 Formal representation

ENTITY IfcLightSourcePositional
SUPERTYPE OF (ONEOF
(IfcLightSourceSpot))
SUBTYPE OF (IfcLightSource);
Position : IfcCartesianPoint;
END_ENTITY;