This random element can be used to control the particle attributes such as position, velocity and color. Usually the random element is controlled by some type of predefined stochastic limits, such as bounds, variance, or type of distribution. The effect he was trying to create was that of a bomb exploding on the surface of a planet and fire spreading out from the point of impact to eventually engulf the planet. Each particle in this system was a single point in space. The fire was represented by thousands of these individual points.
Reeves calls an object made up of particles a fuzzy object .
This space is termed the generation shape of the fuzzy object, and this generation shape may change over time. Each of the above mentioned attribute is given an initial value. These initial values may be fixed or may be determined by a stochastic process. Particle Dynamics - The attributes of each of the particles may vary over time. For example, the color of a particle in an explosion may get darker as it gets further from the center of the explosion, indicating that it is cooling off.