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QuickTime 4 API Documentation

3D Graphics Programming with QuickDraw 3D 1.5.4

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Light Fall-Off Values

Spot lights have a fall-off value that determines the attenuation of the light from the edge of the hot angle to the edge of the outer angle. You can use these constants to specify a fall-off value:

typedef enum TQ3FallOffType {
    kQ3FallOffTypeNone,
    kQ3FallOffTypeLinear,
    kQ3FallOffTypeExponential,
    kQ3FallOffTypeCosine
} TQ3FallOffType;

Constant descriptions

kQ3FallOffTypeNone
The intensity of the light is not affected by the distance from the center of the cone to the edge of the cone.
kQ3FallOffTypeLinear
The intensity of the light at the edge of the cone falls off linearly from the intensity of the light at the center of the cone.
kQ3FallOffTypeExponential
The intensity of the light at the edge of the cone falls off exponentially from the intensity of the light at the center of the cone.
kQ3FallOffTypeCosine
The intensity of the light at the edge of the cone falls off as the cosine of the outer angle from the intensity of the light at the center of the cone.
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