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260 Chapter 11: Space Warps and Particle Systems
single object, and each particle array can emit a
different type of particle.
Tip: Image motion blur, described in Object
Proper t ies (page 1–111)
>MotionBlur
group, is know n not to work properly with
instanced particles. Use object motion blur
w ith instanced part icles, or use image motion
blur with st andard particles.
Standard Particles group
When you choose Standard Part icles in the Particle
Typesgroup,theoptionsinthisgroupbecome
available. C hoose one of the following options to
specify the particle type:
Triangle—Renderseachparticleasatriangle.Use
Triangle particles with noise opacity for steam or
smoke.
Cube—Renders each particle as a cube.
Special—Each particle consists of three intersecting
2D squares. These are effective when you use
a face-map m aterial, descr ibed in
Shader Basic
Par ameters Rollout (page 2–1310)
,optionally
along with an opacity map, to create the effect of a
three-dimensional particle.
Facing—Renders each part icle as a s quare that
always faces the view. Use with an appropriate
opacity map for bubbles or snowflakes.
Co nstant—Provides a particle that remains the
same size, in pixels, specified in t he Size spinner.
This size never changes, regardless of its distance
from the camera.
Impor tant: Youmustrendereitheracameraora
perspective view for Constant particles to render
correctly.
Tetra—
Renders each particle as a mapped
tetrahedron. Use Tetra particles for raindrops or
sparks.
The default alignment of the tetra particles
depends on t he part icle system type and e mitter
setup. To specif y an alignment, use controls in the
Rotat ion and Collision rollout (page 2–264) .
SixPoint—Renders each particle as a six-pointed,
two-dimensional star.
Sphere—Renders each part icle as a sphere.
MetaParticle Parameters group
When you choose the MetaPar ticles option in the
ParticleTypesgroup,theoptionsinthisgroup
become available, and metaballs are used as
part icles. Metapart icles take extra time to render
but are very effective for spraying and flowing
liquid effects.
Tens ion—Determines the t i g htness of the particles,
with regard to their tendency to blend with other
particles. The higher the Tension, the harder the
blobs, and the harder it is for them to merge.
Variation—Specifies the percent of variation of the
Ten s i o n e f fe c t .
Evaluation Coarseness—Specifies how accurately
themetaparticlesolutioniscalculated. The
higher the coarseness values, the less ca lculation.
However, if the coarseness is too high, there may
be little or no metaparticle effect at a ll. Conversely,
if the coarseness is set too low, the time for
calculation can become extremely long.
Render—Sets the coarseness for metaparticles in
the rendered scene. This option is unavailable
when Automatic Coarseness is on.
Viewport—Sets the coarseness for the viewport
display. This option is unavailable when Automatic
Coarseness is on.
Automati c Coars eness—A general rule is to set the
Coarseness va lue between 1/4 and 1/2 the size of
the particles. When this item is on, the render i ng
coarseness is automatically set, based on the size