Understanding a particle system
In 1983, William T. Reeves from Lucasfilm Ltd published a paper: Particle Systems – A Technique for Modeling a Class of Fuzzy Objects. It described the fire simulation effects applied in the film Star Trek II: The Wrath of Khan. Modeling clouds, smoke, and fire is difficult, they do not have rigid primitive surface elements that define their boundaries. They only have a fuzzy volume of particles. Their forms also change over time. Their shapes and forms are recognizable but not accurately predictable.
To model a piece of fire, for example, with particle system, we have the following questions:
How new particles are generated. Is it by birth?
What types of visual and physical properties the new particles have?
How existing particles disappear over time. Is it by death?
How do the visual and physical properties of the existing particles change over time?
How can we render the group of particles in each frame?
By answering these questions, we can define a particle system...
