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Raytrace: Basic Material Extensions Rollout 1517
• Inver se Square—Setsinversesquareattenuation.
Inverse square attenuation is calculated
beginning at the start range, and doesn’t use
the end range. Inverse square is the actual
attenuation rate for light in the real world.
Ho wever, it doesn’t always give the effect y ou
want in a rendered scene.
•
Exponential—Sets exponential attenuation.
Exponential attenuation is ca lculated between
thestartandendrangevalues.Youalsospecify
the exponent to use.
•
Custom Fallof f—Specifies a custom curve to use
for attenuation (falloff).
Start R ange—The distance in world units where
attenuation begins. Default=0.0.
End Range—Sets the distance in world units w here
the ray is fully attenuated. Default=100.0.
This is not used by inverse square attenuation.
Exponent—Sets the exponent used in exponential
falloff. Default=2.0.
This is used only by exponential attenuation.
Color
These controls affect the behavior of light rays as
they attenuate out. By default, as a ray fades out, it
is rendered as the background color.
You can set a custom color instead.
Background—As the ray attenuates out, returns
the background (either the scene’s background or
the background specified locally in the Rayt racer
Parameters rollout) rather than the actua l color of
what the reflected/refracted r ay sees. (Default.)
Specify—Sets the color that is returned by the ray
as it attenuates out.
Ifyouchoosenottousethebackgroundcolor,
black or gray usually work b e st as the attenuation
color,
Custom Falloff group
ThesecontrolsareinactiveunlesstheFalloffType
is set to Custom Falloff.
Custom Falloff—Uses the falloff curve to determine
the falloff between the s tar t and the end ranges.
These are the controls for custom attenuation. The
custom attenuation curve is at the left. The gray
scale bar below the curve shows how the curve will
affect the falloff as light r ays diminish in strength.
Near —Sets the strength of the reflected/refracted
ray at the start r ange distance. This is a normalized
percentage that can range from 0.0 to 1.0.
Default=1.0.
Co ntrol 1—Controls the shape of the curve near the
cur ve start. Default=0.667.
Co ntrol 2—Controls the shape of the curve near the
cur ve end. Default=0.333.
Far—Sets the strength of the reflected/refracted ray
at the end range distance. This is a normalized
percentage that can range from 0.0 to 1.0.
Default=0.0.
Raytrace: Basic Material
Ex tensi ons R oll out
Material Editor > Maps rollout > Click a Map bu tton.
> Material/Map Browser > Raytrace > Basic Material
Extensions Rollout
This rollout contains controls for fine-tuning the
effect of the
Raytr ace map (page 2–1508) .
Interfa ce