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206 Chapter 11: Space Warps and Particle Systems
Tests
The basic function of a test in Particle Flow is to
determine w hether par t icles satisfy one or more
conditions, and if so, make them available for
sending to another event. When a particle passes
a test, it is said to “test True.” To send eligible
particles to another event, you must
wire the test
to that event. Part icles that don’t pass the test (“test
False” ) remain in the event and are repeatedly
subjected to its operators and tests. Or, if the test
isn’t wired to another event, all particles remain
in the event. You can use several tests in an event;
thefirsttestchecksallparticlesintheevent,and
each test after the first checks only particles that
remain in the event.
One test, Spawn, doesn’t actually perform a test,
but simply creates new particles from existing
ones, and sets the new particles’ test result to True
so they’re automatically eligible for redirection to
another event. And the S end Out test simply sends
all particles to the next event by default.
Some tests can also serve as operators, in that
they contain parameters that modif y part icle
behavior. If you don’t wire a test to another event,
it functions only as an operator; the test aspect
doesn’t affect part icle flow.
Tip: Always place a test at the end of its event,
unless you have specific reasons for placing it
elsewhere. That way, all preceding actions can take
effect during each integration step before the test is
evaluated.
All the tests are grouped together in t he Particle
View depot, and are listed in alphabetical order.
All test icons are the same: a yellow diamond
containing a simplified diagram of an electrical
switch.
The Particle Flow tests in the Particle View depot
The tests are:
Age Test (page 2–207)
Collision Test (page 2–208)
Collision Spawn Test (p age 2–211)
Find Target Test (p age 2–214)
Go To Rotation Test (page 2–220)
Scale Test (page 2–223)
Script Test (page 2–225)
Send Out Test (page 2–226)
Spawn Test (page 2–226)
Speed Test (page 2–229)
Split Amount Test (page 2–230)
Split Selected Test (page 2–231)
Split Source Test (p age 2–232)
See also
Operators (page 2–138)
Flows (page 2–204)