8

518 Chapter 8: Modifiers
to a spot light, and then changing the Hair Light
Attr rollout (page 2–1196)
settings for the lig ht.
Geom Shadow—The amount of shadow
contribution hair receives from geometry in the
scene. Default=100.0. Range=0.0 to 100.0.
Geom M at ID—The m aterial ID assigned to
geometry-rendered hair .Default=1.
Frizz Parameters rollo ut
Frizz displacement is accomplished by doing a
Pe rlin noise lookup at the hair’s rest position
root, and then displacing the hair much the way
bump mapping displaces a surface normal. The
frequency of the noise function is set by the Frizz
X/Y/Z Frequency parameters. The magnitude of
the displacement is controlled with Frizz Root and
Frizz Tip. If you set
dynamics mode to Live, you
can see the effects of changing these settings in real
time in the viewports.
1. Frizz Root/Tip= 0.0
2. Frizz Root=50.0, Frizz X/Y/Z Freq=14.0
3. Frizz Root=150.0 , Frizz X/Y/Z Freq=60.0
4. Frizz Tip =30.0, Frizz X/Y/Z Freq=14.0
5. Frizz Root=50.0, Frizz Root=100.0, Frizz X/Y/Z Freq=60.0
Frizz actually calculates two noise fields, both of
which use the same f requency settings and tip/root
amplitudes. One of the noise fields is static relative
to the hair. The Anim parameters let you animate
the second noise field through the hair over time.
This is useful for things like grassy fields, where
it would be ov erkill to compute real dynamics.
These parameters give you a similar result, at a
small fraction of the computational overhead.