Inside Macintosh: 3D Graphics Programming With QuickDraw 3D /

Chapter 8 - Light Objects / Light Objects Reference

Constants

Light Attenuation Values

Most types of lights have an attenuation value that determines how quickly, if at all, the intensity of a light changes as a function of the distance of the illuminated object from the light source. You can use these constants to specify an attenuation value:

typedef enum TQ3AttenuationType {
   kQ3AttenuationTypeNone,
   kQ3AttenuationTypeInverseDistance,
   kQ3AttenuationTypeInverseDistanceSquared
} TQ3AttenuationType;

Constant descriptions

kQ3AttenuationTypeNone

The intensity of the light is not affected by the distance from the illuminated object.

kQ3AttenuationTypeInverseDistance

The intensity of the light is inversely proportional to the distance from the illuminated object.

kQ3AttenuationTypeInverseDistanceSquared

The intensity of the light is inversely proportional to the square of the distance from the illuminated object.