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186 Chapter 11: Space Warps and Particle Systems
Particles falling onto a t wo-elemen t cylinder
Left: Allow Multiple Elements is off; Right: Allow Multiple
Elements is on.
Continuous Upda te—When on, the shape of the
mark is recalculated at each f r ame, according to
the current positions of the particle and the contact
surface. This option can consume a great deal of
CPU time. Available only with Box Intersection.
Generate Mapping Coords.—Allows correct
application of the shape mark when using a
mapped material. Default=on.
If you’re not using a mapped material, you can
savememorybyturningthisoff.
Pivot Offset % —Shifts the position of the shape
mark along its length dimension with respect to
the pivot of the impacting particle. Default=0.0.
Range=-50.0 to 50.0.
By default, the center of the mark’s leng th
dimension coincides with the point where the
particle’s pivot strikes the contact object. This
setting lets you offset the mark’s position to
anywhere along its length.
Note: The width dimension and the Box
Intersection’s height dimension are always
centered at the intersection of the particle pivot
and the contact object’s surface.
Surf ace Offset—Specifies the distance of the
shapemarkabovethecontactobject’ssurface.
Default=0.001.
The mark is slightly elevated above the contact
geometry to achieve the visual effect of the mark
spot overlapping the contact geometry. This
parameter is not animatable.
Offset Variation—Specifies the maximum extent
of a random variation in the actual surface offset
among particles. Default=0.0.
Adjusting this value can help to alleviate rendering
artifacts with overlapping marks.
Ver tex Jitter—Specifies the maximum extent of a
randomvariationinthepositionsofverticesof
marks created using the Box Intersection method.
Available only with the Box Intersection method.
Default=0.0.
Adjusting this value can help to alleviate rendering
artifacts with overlapping marks.
Uniqueness group
The Uniqueness setting enables changing the
randomization of the size/width variation.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Material and Mapping
Particle Flow provides three operators for
applyingmaterialstoparticles. Togivethe
same appearance to all particles throughout an
event, use Material Static Operator (page 2–187).
If you’re using a compound material such as
Multi/Sub -Ob ject (page 2–1594), you c an assign
different sub-materials to different par ticles w ith
the Material Frequency operator (page 2–189).And
to assign materials that change in appearance over
time, use the Material Dynamic operator (page
2–191).
Related to this is the Mapping operator (page
2–195), which lets you give the same mapping
coordinates to the entire surface of each particle in
an event, thus using a single pixel f rom a material