Ultimate Game Design : Building game worlds

out of your 3-D package. This generates a file with data about each particle’s position
or behavior over a given period of animation frames (for example, from frame 1 to
frame 30). Using this method, your game engine can read in this data file and re-create
the particle system effect that you built up in your 3-D package.
Another option is to render out the particle behaviors as an animation sequence,
and stamp this onto a polygon surface. You can give your computer a real headache
doing this. I’ve crashed many of them. When you start to ask your computer to render
particle system output, keep the numbers low. To begin experimenting, keep
your number of particles reasonable (less than 100) and your number of animation
frames manageable (roughly 30 frames).
Once you have your particles behaving like fire and colored like fire, you create a
render sequence of your fire. Next, you could create a simple polygon plane and map
your fire render sequence to the polygon plane. Finally, you parent (or associate) the
plane with the fire on it to the kindling in your hearth and move the plane into position.
You now have a particle-based fire effect for your hovel!
To extend this idea to another example, if you were building vehicle exhaust, you
would follow the same procedure and parent your exhaust plane to the vehicle’s tailpipe.
Ideally, it’s nice to have a toolset that allows you to simply position emitters in a
scene and then tweak the particle behavior in real time. Figures 3-11 and 3-12 show
scenes constructed using the WildTangent Studio (WTStudio) tool. This tool enables
users to create emitters and adjust particle behavior in real time.
FIGURE 3-11
Use of emitters for steam effect
C H A P T E R 3
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Lighting, Texturing, Particles, Effects, and Audio