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240 Chapter 11: Space Warps and Particle Systems
Particles with various materials assigned to them
You make this choice in the Material Mapping and
Source group near the bottom of the Particle Type
rollout. Choose Icon to use t he material assigned
to the particle system, choose Picked Emitter
to use the material assigned to the distribution
object, or choose Instanced Geometry to use
the m aterial assigned to the instanced objects.
Note that this third option is available only when
Instanced Geometry is the current particle 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 t he material from the distribution object.
Impor tant: A particle-system object, like any other
object, can car ry only a single material at any time.
Thus, if you choose either Picked Emitter or Instanced
Geometry, an instance of the chosen material is actually
copied to the particle system, overwriting the material
assigned to the emitter. If you want to restore the
emitter material, choose Icon, and then reassign the
material from the Material Editor or the Browser.
No ma tter what choice you make, if the material
used is not mapped, then all particles take on the
surface properties of the material, regardless of
which object is used as the source of the material.
Achieving Par ticle Motion Blur
Particle motion blur is actually the result of
vary ing the opacity and the length of p articles
based on their speed. To accomplish this requires
coordination between material assignment and
the sett ings in the particle systems. Follow these
instructions:
•UsetheParticle MBlur map (page 2–1676) in
the material that you assigned to the particles.
For best results, assign 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 rti cle Sy s tems
Mapped materials affect particles differently,
depending on the source of the material.