Particles don't have to be tiny—a billboard example

The examples we saw have one thing in common—they all consisted of a large number of relatively small particles. Also, even though generating many small particles in a scene is a widespread technique, it is not the only way particles can be used.

Here is another scenario. At the beginning of this chapter we introduced particles by briefly discussing two examples—one referred to adding trees to your scene and the other to shiny balls. Let's take a closer look at the tree example. The point that was made is that loading a tree model, which is exported from a 3D modeling tool would take up a lot of polygons. Instead, using a particle with a 2D graphic of a tree as material, would massively cut down the number of polygons.

What you could do, and what actually happens a lot in 3D applications is create a scene with partly 3D objects and partly particles that suggest 3D objects, such as the tree example. You could even build a whole scene made...