2.3 Particle Dynamics
A particle's position in each succeeding frame can be computed by knowing its velocity (speed and direction of movement). This can be modified by an acceleration force for more complex movement, e.g., gravity simulation.
A particle's color can be modified by a rate-of-color-change parameter, its opacity by a rate-of-opacity-change parameter, and its size by a rate-of-size-change parameter. These rates of change can be global, i.e. the same for all particles, or they can be stochastic for each particle.