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Dynamics Rollout (Hair and Fur) 545
Dynamics R ollout (Hair and Fur)
Select an object with the Hair And Fur modifier applied. >
Modify panel > Dynamics rollout
For hair to seem natural in an animation, it must
respond to the motion of the body it’s attached
toandtoexternalinfluencessuchaswindand
gravity. Hair’s Dynamics functions let the h air
behave like real-world hair, in i nteractive (Live)
or Precomputed mode.
Designating Collision Sur faces
Hair dynamics uses guide hairs to calculate
collision. To reduce computation, you have to
explicitly designate the objects with which hair will
collide. The object from which the hair grows is a
special case: to have hair collide with this object
(for example, a human head), simply turn on Use
Growth Object.
If there is a collision object that you want more
than one Hair mo difier to interact with, you have
toaddthatobjectasacollisionobjectforeach
different Hair And Fur modifier.
There are two different methods for calculating
collision: Sphere and Polygon. Spherical collision
uses a bounding sphere for collision objects;
polygonal collision uses the collision object’s
actual geometry. The Polygon option is more
accurate, but the Sphere option is quicker to
calculate.
Pr ocedur es
Ex ample: To v iew ha ir dy na mics in rea l time:
1.
Apply the Hair And Fur modifier to an object.
2. OntheDynamicsrollout(scrollthecommand
panel down to view it), set Mode to Live.
3. Move the object around.
The hair moves realistically.
4. On the Tools rollout, click Regrow Hair.
The hair resumes its default position, growing
straight out of the 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
animation do esn’t restart at the first frame.
7. On the Tools rollout, click Regrow Hair again.
8. Add a Wind space warp to the scene.
9. On the Dynamics 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 grav ity, but
simply blown by the wind. Again, the effect is
cumulat ive and t he animation doesn’t repeat.
All of this animation tak es place only in real
time; no keyfr ames are set, so it can’t be
rendered. To learn how to set up a renderable
dynam ics simulation with Hair, see the
following procedure.
To generate a precomputed dynamics simulation
wit h H a ir:
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.