8

52 Chapter 11: Space Warps and Particle Systems
space warp is always applied after any transforms
or modifiers.
When you bind multiple objects to a space warp,
the space warp’s parameters affect all the objects
equally. However, each object’s distance from the
space warp or spatial orientation to the warp can
change the warp’s effect. B e cause of t his spatial
effect, simply moving an object through war ped
space can change the warp’s effect.
You can also use multiple space warps on one or
more objects. Multiple space warps appear in an
object’s stack in the order you apply them.
Note: You can take advant age of the AutoGrid
feature to orient and position new space warps
w ith respect to existing objects. See
AutoGrid
(page 2–7)
for details.
Space Warps and Supported Objects
Some types of space war ps are designed to work on
deformable objects, such as geometric primitives,
meshes, patches, and splines. Other types of warp s
work on particle systems such as Spray and Snow.
Five space warps (Gravity, PBomb, Wind, Motor,
andPush)canworkonparticlesystemsandalso
serve special purposes in a dynamics simulation.
In the latter case, you do not bind the warps to
objects, but r ather assign them as effects in the
simulation.
On the Create panel, each space warp has a rollout
labeled Supports Objects Of Type. This rollout
lists the kind of objects you can bind to the warp.
Basics of Using Space Warps
Follow these genera l steps to use space w a rps:
1. Create the space warp.
2. Bind objects to the space warp.
Click Bind To Space Warp on the main
toolbar (available from the Select And Link
flyout), and then drag between the space warp
and the object.
The space warp has no visible effect on your
scene u ntil you bind an object, system, or
selection set to it.
3. Adjust the space warp’s parameters.
4. Transform the space warp with Move, Rotate,
or Scale. The t ransforms often directly affect
the b ound object.
You can animate space warp parameters and
transforms. You can also animate space warp
effects by animating transforms of an object bound
to the warp.
Particle Leak age and Deflector Space
Wa rps
Adeflectorisaspacewarpthatactsasabarrierto
particles in particle systems. Occasionally stray
particles can leak through a deflector under the
following circumstances:
• When a particle happens to hit the deflector too
near the end or beginning of a time interval,
and numerical error in the solution doesn’t
report a hit
•Whenaparticlehitstooneartheedgeofaface
referenced by a UDeflector, and neither face
finds it
• When a particle is moving quickly and first
appearstooclosetothedeflector,sothevery
firstupdatecyclewithintheparticlesystem
takes it past the deflector w ithout the deflector
ever seeing it
Often this isn’t a problem b e cause the particles
bounce off solid objects, so you don’t see the errant
particles. When it does cause problems, you can
use a planar deflector instead of a UDeflector , a
collection of planars to approximate the mesh, or a
simple mesh to replace the planar. The solutions
vary, so where one has a glitch the other might
work just fine.