8

Particle Type Rollout 261
of the particles, and the view p ort coarseness is set
to about twice that of the rendering coarseness.
One Connected B lob—When off (the default),
all particles are calculated; when on, a shortcut
algorithm is used that calculates and displays only
thoseparticlesthatareadjoiningorcontiguous
to each other.
Note: One Connected Blob mo de speeds p art icle
calculations, but you should use it only when your
metaparticles f orm one connected blob, as the
labelindicates.Thatis,allparticles’blobsmust
be touching. For example, if you were to use One
Connected Blob on a st ream of part icles containing
a mass of 10 contiguous particles followed by a
space, then 12 contiguous particles followed by
anotherspace,andfinally20contiguousparticles,
one of the p a rticles will be chosen, and only the
mass connected to that particle will be displayed
and rendered.
Tip: When in doubt, leave this option off. If you
think all your particles are contiguous and want to
savetime,turnonOneConnectedBlob,andthen
display var ious frames to see if everything appears.
Object Fragment Controls group
With a particle array, when you choose the Object
Fragmentsparticletype,theitemsinthisgroup
become available, and the object-based emitter is
exploded into fragments, rather than being u sed
to distribute particles.
Note: To see the fragments in the viewpor t s,
choose Mesh in the Viewport Display g roup near
the bottom of the
Basic Parameters rollout (page
2–254)
.
The items in this group include a Thickness
spinner, along with three option buttons that
determinehowthefragmentsareformed.
Tip: There is no automatic way to hide the
distribution object that explodes into fragments.
To create the illusion that an object is exploding,
you must either set the original object to be
invisible at the st art of the ex plosion, as described
in
Add Visibility Track (page 2 –533) ,ormoveor
scale the original object so it doesn’t remain in
view.
Thickness—Sets the thickness of the fragments.
At 0, the fragments are single-sided with no
thickness. When greater than 0, the fragments are
extruded, at fragmentation time, by the amount
specified. The outer and inner surfaces of the
fragment use identical smoothing, which is picked
up from the object-based emitter. The edges of the
fragments are not smoothed.
The three options that follow spe cify how the
object fragments.
All Fa ces—Each face of the object becomes a
part icle. This results in triangular part icles.
Number of Chunks—The object breaks into
irregular fragments. The Minimum spinner,
below, specifies the minimum number of
fragments that will appear. The method of
calculating the chunks may result in more
fragments than specified.
Mi nimum—Determines a number of "seed" faces in
the geometry. Each seed face collects connect ing
faces sur rounding it until all available faces are
exhausted. Any leftover faces become unique
particles, thus increasing the minimum number
of fragments.
Smoothing Angl e—Thefragmentsarebroken
based on the angles between face normals, as
specified in the Angle spinner. Generally, t he
higher the A ngle value, the fewer the numb er of
fragments.
Angle—Sets the amount of smoothing angle.