Flocking

Boids Simulation Boids - Wikipedia 

This program simulates simple agents (boids) that move according to a set of three basic rules: separation, alignment and cohesion. The result, akin to a flock of birds, a school of fish, or a swarm of insects, was developed for motion picture visual effects.

Boids is an artificial life program, developed by Craig Reynolds in 1986, which simulates the flocking behaviour of birds, and related group motion. His paper on this topic was published in 1987 in the proceedings of the ACM SIGGRAPH conference.[1] The name "boid" corresponds to a shortened version of "bird-oid object", which refers to a bird-like object.[2] Reynolds' boid model is one example of a larger general concept, for which many other variations have been developed since. The closely related work of Ichiro Aoki is noteworthy because it was published in 1982 — five years before Reynolds' boids paper.[3]