8

508 Chapter 8: Modifiers
2.
OntheDynamicsrollout(scrollthecommand
panel down to v iew it), set Mode to Live.
3. Move the object around.
The hair moves realistically.
4. On the To ols rollout, click Regrow Hair.
The hair resumes its default position, growing
straig ht out of t he object.
5. Click the Play Animation button.
6. The hair settles and droops, as if affected by
gravity. Note that, as the animation repeats,
the effects of grav ity are cumulative; the hair
animat ion doesn’t restart at the first frame.
7. On the Tools rollout, click Regrow Hair again.
8. Add a Wind s pace warp to the scene.
9. On the D ynamics rollout, set Dynamics Params
>Gravityto0.0.
10. In the External Forces group (at the bottom
of the Dynamics rollout), click Add and then
select the Wind space warp.
11. Play the animation again.
This time, the hair isn’t affected by gr avit y, but
simply blown by the wind. Again, the effec t is
cumulative and the anim ation doesn’t repeat.
Allofthisanimationtakesplaceonlyinreal
time; no keyf rames are set, so it can’t be
rendered. To learn how to set up a renderable
dynamics simulation with Hair , see the
following procedure.
To genera te a precomputed dy nami cs si mulation
wit h H a i r :
1.
Apply the Hair and Fur modifier to an object.
2. Set up the animation. It could simply be motion
of the growth object, or you could use the
Dynamics rollout > External Forces group to
add space warps, such as Wind, that should
affect the hair. Actually, because the hair is
affected by its own gravity by default, you don’t
need to set up any explicit animation at all to
see hair dynamics.
3. On the Modify panel > Dynamics rollout, use
the Collisions group to set objects the hair
should collide with. Also set other simulation
parameters in the Dynamics Params group.
4. In the Stat Files group, click the ellipsis (... )
button. UsetheSaveAsdialogtospecify
the location and name of the stat files to be
generated.
Note: When you run the simulation, Hair will
generateaseparatestatfileforeachanimation
frame.
Impor tant: If you plan to render the animation with
a networked render farm, make sure the path you
specify can be seen in exactly t he same way from
each node on the render farm. If stat files aren’t
found, hair will be stiff and just oriented to the skin
as it moves. If the wrong stat files are found, hair can
float right off a n object.
Tip:
If using Windows XP, click the My Network
Places button to set a path using the UNC
convention,evenifit’sonalocaldrive.Sucha
path can be accessed readily by other computers
on the network.
The path and stat file name appear in the text
field next to the ellipsis button.
5. In the Simulation g roup, set the frame r ange for
the simulation and then click Run.
Hair runs the dynamics simulation and
generates a stat file for each frame in the
animation. It also automatical ly sets the mode
to Precomputed, so when you play or render
the animation, it reads the st at files and uses
the information for the hair positioning in each
frame.
6. Pla y the animation.
The dynamics si mulation stored in the stat files
appears i n the viewports.