UDK includes a bag of fireworks called Cascade. Cascade is not only a sprite particle generator but can also produce trailing ribbons, laser beams, and geometry arrays. Cascade has many features, and can be daunting to learn, but with patience proves to be a very complete and comfortable Particle Editor. Earlier in the book, in Chapter 2, Notes From an Unreal World, in the recipe Creating a steamy plume in Cascade, we covered the basics of a particle emitter's anatomy.

Now we'll look closer. One of the most important features of Cascade to learn early on is handling the Distribution values for the various modules, which provide a way to set values or value ranges to parameters of an emitter, such as direction, speed, age, color, and rotation. Unfortunately it is also a lot to cope with on your first try. Distributions are split up into Constants (static single values), Vectors (XYZ values), and Particle Parameters (named values something else can access and affect). The properties of each parameter can have Min and Max ranges to create variety and complexity. Particles move and they change color, so they also have Point entries [0], [1], [2], and so on, to add curves for animation through keys on a timeline. If there were a pipeline for creating particles that could be followed every time, it might begin with assigning a Material, deciding which modules will work to create the effect, then working out the distribution values to control how much, and how fast, and how big. Once you are comfortable with that you can look at making Emitters talk to each other through events and through Kismet and in code.