8

Basic Parameters Rollout (PArray) 255
object-based emitter, and is used either as the
source geometry over which particles form, or
the source geometry used to create particles that
appear to be fragments of the object.
Object text f ield—Displaysthenameofthepicked
object.
Par ticle Formation group
Theseoptionsdeterminehowstandardparticles
are initially distributed over the surface of
the object-based emitter. These controls are
available only w hen the picked object is used
as a distribution grid for standard particles,
MetaParticles, or instanced geometry; see
Part icle Type rollout (page 2–258) .WhenObject
FragmentsischosenintheParticleTyperollout,
these controls are unavailable.
Over E nti re Surf ace—Emits particles randomly
over the entire surface of the object-based emitter.
This is the default choice.
Along V isible Edges—Emits particles randomly
from the v isible edges of the object.
At All Ver tices—Emits particles from the vert ices
of the object.
At Distinct Points—Places a specified number of
emitterpointsrandomlyoverthesurfaceofthe
object.
Total—Specifies the number of emitter points used
when At Distinct Points is chosen.
At Face Centers—Emits part icles from the center
of each triangular face.
Use Selected S ubObjects—With mesh-based
emitters, and to a limited extent with patch-based
emitters, limits the source of the particle stream to
the sub-object selection passed up the modifier
stack in the object-based emitter. For example, if
your emitter object is a cylinder converted to an
editable mesh, and the top cap of that c ylinder is
selected at the Face or Polygon sub-object level,
if Use Selected SubObjects is on
and Particle
Formation group > At Face Centers is on, the
particleswillstreamonlyfromthetopcapofthe
cylinder. Default=off.
Thetypeofparticleformationyouspecify
determines the type of sub-object geometry used,
as follows:
•
Over Entire Sur fa ce—Faces
•
Along V isible Edges—Edges
•
At Al l V er tices—Ve r t i c e s
•
At Distinct Points—Faces
•
At Face Centers—Faces
If you’ve converted your object to an editable
mesh, and selected different sub-object sections
of it with vertex, edge, and face selection, as you
switch particle formation options, you’ll see the
particles emit from different areas of the object.
Note: UseSelectedSubObjectsisapplicableto
patchobjectemittersonlyatthepatchand
element sub-object levels, and is not applicable
NURBS objects used as emitters.
Tip: You can best see the emission patterns by
first setting Speed on the Particle Generation
rollout > Particle Motion group to 0. Mo ve to a
frameinwhichtheparticlesappear,andthen
choose the various particle formation options.
Display Icon group
Ad justs the display of the particle-system icon in
the viewports. (The particle-system icon is usually
called the "emitter." In this case, however, it doesn’t
actually emit particles, so we’re avoiding the term.)
Icon Size—Sets the overall size of the icon, in units.
Icon Hidden—When on, the PArray icon is hidden
in the viewports. Note that the icon does not
render, in any case. Default=off.