8

284 Chapter 18: Effects and Environments
Left: Fog with noise
Right: Decreasing the size
Phase—Controls the speed of the wind. If you
have Wind Streng th also set to greater than 0, the
fogvolumeanimatesinaccordancewiththewind
direction. With no Wind Strength, the fog churns
in place. Because t here’s an animation track for
phase, you can use the Function Curve editor to
define precisely how you want your wind "gusts"
to occur .
Wind moves the fog volume in the specified
direction over time. Wind is tied to the phase
parameter so as the phase changes, the wind
moves. If Phase isn’t animated there will be no
wind.
Wind S trength—Controls how fast the smoke
moves away from the wind direction, relative to
phase. As mentioned above, if the phase is not
animated then the s moke won’t move, regardless
of the wind s trength. By having the phase animate
slowly with a large wind strength, the fog moves
more t han it is churns.
Alternatively, if the phase changes rapidly while
the wind strength is relatively small, the fog will
churn fast and dr ift slowly. If you want the fog to
justchurninplace,animatethephasebutkeep
wind strength at 0.
Wind from the—Defines the direction the wind is
coming from.
Volume Light Environment Effect
Rendering menu > Environment > Environment and
Effects dialog > Environment panel > Atmosphere rollout
>Add>VolumeLight
Volumetric lig ht used in a complex environment w ith
shadows and noise.
VolumeLightprovideslighteffectsbasedonthe
interaction of lights with atmosphere (fog, smoke,
and s o on).
This
plug-in (page 3–1089) provides effects such
as radial glows fo r
omni lights (p age 3–1077) ,
conical glows for spotlights, and paral lel beams of
fog for directional lig hts. Objects within the light
volume can cast shadows within the spotlight’s
cone, if using shadow maps as a shadow generator.
A simplified example where the light cone is clearly visible
on the right.
Volume Light renders only in Camera or
Perspective views. Orthographic or User vie ws
don’t render Volume Light effects.