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236 Chapter 11: Space Warps and Particle Systems
Particles with various materials assigned to them
You make this choice in t he Material Mapping and
Source group near the bottom of the Particle Type
rollout. Choose Icon to use the material assigned
to the particle system, choose Picked Emitter
to use the material assigned to the distribution
object, or choose Instanced Geome try to use
the m aterial assig ned to the instanced objects.
Note that this third option is available only when
Instanced Geometry is the current part icle type
(selectedintheParticleTypesgroupatthetopof
theParticleTyperollout).
Note: SuperSpray and Blizzard don’t have
distribution objects. PCloud has a distribution
objectbutyoucan’tgetthematerialfromit. In
these cases, a radio button lets you use the material
from the instanced geometry. Only PArray lets you
get the material from the distribution object.
Impor tant: A particle-system object, like any other
object, can carry only a single mater ial at a ny time.
Thus, if you choose either Picked Emitter or Instanced
Geometry, an instance of the chosen material is ac tually
copied to the particle system, overwriting the material
assigned to the emitter. If you want to restore the
emitter material, choose Icon, and t hen reassign the
material from the Material Editor or the Browser.
No matter what choice you make, if the material
used is not mapped, then all part icles take on the
surface properties of the material, regardless of
which object is used as the source of the material.
Achiev ing Par ticle M otion Blur
Particle motion blur is actually the result of
varying the opacity and the length of particles
based on their speed. To accomplish this requires
coordination between m aterial assig nment and
the sett ings in the particle systems. Follow these
instructions:
•Usethe
Part icle MBlur map (p age 2–1486) in
the material that you assigned to the particles.
For best results, a ssign it as an opacity map.
• Makesurethattheparticlesystem,PArray,
PCloud,andSuperSpray,orSpray,supports
theParticleMBlurmap.
• Choose Rotation and Collision rollout >
Spin Axis Controls group > Direction of
Travel/Mblur option.
• Inthissamegroup,settheStretchspinner
greater than 0 to stretch the particles as a
percent of their length based on the particle
Speed setting.
• Use the correct type of particle. MBlur works
on all particle types except Constant and
Facing.
Note: Instanced objects with multi/sub-object
materials cannot be image motion blurred.
Using Mapped Materials with
Pa rt icle S y st ems
Mapped materials affect part icles differently,
depending on the source of the material.