2012

Table Of Contents
Attenuation Properties (Point Lights and Spotlights)
Attenuation controls how light diminishes over distance. The farther away
an object is from a light, the darker the object appears. You can specify no
attenuation, inverse linear, or inverse squared (POINTLIGHT, SPOTLIGHT).
Attenuation is not active for photometric lights.
None. Sets no attenuation. Objects far from the point light are as bright
as objects close to the light.
Inverse Linear. Sets attenuation to be the inverse of the linear distance
from the light. For example, at a distance of 2 units, light is half as strong
as at the point light; at a distance of 4 units, light is one quarter as strong.
The default value for inverse linear is half the maximum intensity.
Inverse Square. Sets attenuation to be the inverse of the square of the
distance from the light. For example, at a distance of 2 units, light is one
quarter as strong as at the point light; at a distance of 4 units, light is one
sixteenth as strong.
Another way to control the start point and end point of light is to use limits.
Limits work like clipping planes to control where light is first emitted and
where it stops. Using limits can increase performance by removing the need
for the program to calculate light levels where the light is already practically
invisible.
802 | Chapter 13 Render Drawings