In 1986 Craig Reynolds made a computer model of the motion of groups of animals, such as flocks of birds, or shaols of fish.
It was based on 3D computational geometry, as normally used in computer animation or computer aided design.
He called the generic simlulated creatures boids. Each creature obeyed three basic rules which determined its direction and speed of travel. These rules calculate the direction of travel relative to the position and velocity of the boid's nearby flockmates. ( The next page gives more information on the details of these three rules).
The flocking requires that each boid reacts only to nearby flockmates rather than the whole flock. Flockmates outside the choosen distance and angle ( i.e. a circle drawn from the centre of a boid of radius distance ) are ignored. In real world terms, we might think of a fish in murky water that can only see nearby fish, not the whole shaol, or a bird in fog.
The model used by Craig Reynolds also included obstacle avoidance ( dodging objects within the boid's static environment ) and goal seeking.
Craig Reynolds published a technical paper on the boids in 1987. He also demonstrated the boids model in a short film entitles Stanley and Stella in: Breaking the Ice, which was first shown at the Electronic Theatre at SIGGRAPH '87. Further he gave a presentation on the boids at the ALife workshop, organised by Chris Langton in 1987.
Click the link below to see the rules of the boid simulation...