Game Physics Engine Development, 2nd Edition

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Exactly the same kind of particle system is used in many game engines. By setting

the gravity of particles to a very low value, or even having gravity pull some kinds

of particle upward, we can create smoke, fire, waterfalls, explosions, sparks, rain, and

many other effects.

The difference between each type of particle is simply one of rendering. Particles

are normally drawn as a flat bitmap on screen, rather than as a 3D model. This is the

approach I’ve used in the demo.

Most production particle systems also allow particles to rotate—not the full 3D

rotation we will cover later in this book, but a screen rotation, s o that each particle

bitmap is not drawn with the same orien tation on screen. It can be useful to have this

rotation