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188 Chapter 11: Space Warps and Particle Systems
11.
Click the Shape Facing operator, and in its
rollout, click the Look At Camera/Object
button, and then select the camera.
12. In the Size/Width group, increase In World
Space > Units to about 15.
13. Add a Material Dynamic operator to Ev ent 01,
and assign it the material from the beginning
of this procedure.
14. Turn on Show In View p or t.
15. In the Animated Texture group, make sure
Same As Particle ID is chosen, and turn on
Reset Particle Age.
Always choose Same As Particle ID with an
animated texture, and one of the Sub-Material
Rotoscoping options when using a compound
mater ial.
Turning on Reset Part icle Age causes the
software to set particles to age 0 as they enter the
event. In this example, the part icles are bor n in
the event, so technically it’s not necessary to
turn on Reset Particle Age. However, it’s a good
habit to get into to ensure that the animation
always plays from the first frame.
16. Play the animation.
In the viewport, the bitmap animation advances
as the part icles move, but al l the particles show
thesameframe,regardlessofage. Thisis
anomalous behavior related to the limitations
of viewport interactivity. The particles render
correctly, however.
17. Render the animation.
As each particle is born, it begins displaying
the animation from the first frame. A t each
frame, each particle’s age is incremented, and it
displays the next frame from the applied map.
Example: To use the Particle Age map:
The Particle Age map (page 2–1485) applies up
to three different colors or maps to particles
throughout their life s p a n, g radually changing
from one to the next as the particles age. This
effect can be used, for example for sparks flying
from a fire: At first they’re yellow; then, as they
cool down, they turn r ed, and finally they become
gray ashes. In order for Particle Age to know how
far a particle has progressed through its life sp an,
theparticlehastobegivenafinitelife.Youdothis
using the
Delete operator (page 2–142) .
1. Start or r eset the program, and add a Particle
Flow system.
2. Open Particle View and the Material Editor.
Position them side by side.
3. In Particle View, add a Material Dynamic
operator and a Delete operator to Event 01.
For Particle Age to work, the Delete operator
must be in the same event as the Material
Dynamic operator. Alternatively, you can add
the D elete operator to the
global event (page
3–1043)
so that it affects every event.
4. Click the Delete operator, and in the parameters
panel, choose By Particle Age, and set Life
Span=100 and Variation=0.
This gives each part icle a life span of 3 1/3
seconds.
5. Click the Ma terial Dynamic operator.
6. IntheMaterialEditor,assignaParticleAge
map as the Diffuse map. On the Particle Age
Parameters rollout, set three different colors,
such as red, green, and blue. Also change
the Age percent age values as necessary. For
example, if you w ant each p article to show the
second color a third of the way through its life
instead of ha lfway, change Age #2 to 33.
7. Dragtheactivematerialfromitssampleslotto
the material button on the Ma terial Dynamic
parameters rollout in Particle View. When the
Instance (Copy) dialog appears, click OK to
accept the default choice: Instance.
8. In the Material Dynamic parameters, make
sure Assign Material ID is on.