Boids: simulating the flocking behavior of birds

Bird-oid objects or “boids” for short is a simple way to simulate the flocking behavior of birds using some simple rules. Boids exhibit emergent behavior (similar to pursuit curves) which means that the complexity of Boids arises from the interaction of many boids together adhering to a set of simple rules.

A typical simulation has three main rules:

1. Separation: boids try to avoid colliding with each other. This is implemented by applying mutual repulsion if the boids get too close to each other.
2. Alignment: boids try to steer towards the average heading of their flockmates. This can be implemented by gently accelerating the boids to the average flock velocity.
3. Cohesion: Flockmates try to stay close to the center of mass of the flock. Implemented by applying a mutual attraction between flockmates towards the center.

More simple rules such as these can be added to add additional behavior, such as perching.

A full page demo is available here.
The source code is available here.