8

Hair Overview 503
Frizz settings affect the hairs but not the guides.
Note: By default, a percentage of hairs appear in
the viewports, but guides do not. You can adjust
these settings, as well as colors, with the Display
rollout p ar ameters.
Dynamic simulations happen at the guide level,
while displacement and coloration happen at the
interpolated render hair level. The computational
savings of doing hair this way are substantial,
sowhileitmightpreventdirectcontrolofeach
and every hair, creating realistic hair would be
impossible to do without the abstraction process.
Gr owing a nd R ender i ng Ha ir
TheHairsoftwarerecognizestwotypesofgrowth
objects: splines and mesh. The spline type will
grow hair between or on two or more splines, in
an interpolated or non-interpolated manner, as
long as they are all part of a single object. The
polygonal-mesh growth type will grow hair from
triangle mesh surfaces. You needn’t do anything
specialtotellHairwhichtypeofgrowthyouare
creating; the Hair and Fur modifier will determine
the appropriate method f rom the objects you apply
it to.
To grow hair from splines, you can minimally
just draw several splines, combine them into a
single object if necessary, and then apply the Hair
and Fur modifier. You will see some preview
int erpolated hairs appear. With Interpolation on,
the order of the splines is important because Hair
uses the order to create hair in between the splines.
If the interpolat ion seems incoherent, you might
need to physically rearrange the splines.
Using a spli ne emitter, Hair interpolates hair growth
between pairs of splines in logical, numerical order.
Left: Splines in sequential order result in predictable hair
growth.
Right: Splines in nonsequential order can produce
undesirable results.
To g ro w h a i r f ro m a p o ly m e s h o b j e c t , s ele c t t h e
object, and then apply the Hair and Fur modifier.
Using Ins ta nced Ha ir
Besides the built-in hair strands, w hich are created
atrendertime,youcanassignanysourceobjectas
hair strands, using the Instance Node controls on
the Tools rollout. Different controls available both
in 3ds Max and in Hair can affect the instanced
hair. For example, in the following illustration, the
original orientation of the source object affects its
orientation when used as hair strands.
Rotating the source object a ffects the hair orientation.