2009

Example: To use the Particle Age map:
The
Particle Age map on page 5889 applies up to three different colors or maps
to particles throughout their life span, gradually 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 red, and
finally they become gray ashes. In order for Particle Age to know how far a
particle has progressed through its life span, the particle has to be given a
finite life. You do this using the
Delete operator on page 2848.
1 Start or reset 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 Delete
operator to the
global event on page 7997 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 particle a life span of 3 1/3 seconds.
5 Click the Material Dynamic operator.
6 In the Material Editor, assign a Particle Age 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 percentage values as necessary. For
example, if you want each particle to show the second color a third of
the way through its life instead of halfway, change Age #2 to 33.
7 Drag the active material from its sample slot to the material button on
the Material 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.
If it isn't, the particles all change color at the same time.
There's no need to turn on Show In Viewport; the Particle Age map doesn't
appear in the viewports.
9 Render the animation, or a few representative frames.
As each particle falls, it gradually changes color, with the oldest particles
changing first.
2928 | Chapter 14 Space Warps and Particle Systems