9

288 Chapter 18: Effects and Environments
Left: Fog with noise
Right: Decreasing the size
Phase—Controls the speed of the w ind. If you
have Wind Strength also set to greater than 0, the
fogvolumeanimatesinaccordancewiththewind
direction. With no Wind Strength, the fog churns
in place. Because there’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 n ot
animated then the smoke won’t move, regardless
of the wind strength. By having the phase animate
slowly with a large wind strength, the fog moves
more than it is churns.
Alternatively, if the phase changes rapidly while
the wind strength is relatively small, the fog will
churn fast and drift 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 light used in a complex environment with shadows
and noise.
VolumeLightprovideslighteffectsbasedonthe
interaction of lights with atmosphere (fog, smoke,
and s o on).
This plug-in (page 3–995) provides effects such as
radial glows for omni lights (page 3–983),conical
glowsforspotlights,andparallelbeamsoffogfor
directional lights. Objects within the light volume
can cast shadows within the spotlig ht’s cone, if
usingshadowmapsasashadowgenerator.
A simplified example where the light cone is clearly visible on
the right.
Volume Light renders only in Camera or
Perspect ive views. Orthographic or User views
don’t render Volume Light effects.