Boid
Well-known type of agent-based system that realistically simulates the complex flocking behaviors of birds and fish using simple rules. Each "boid" is an autonomous agent that is only aware of its immediate neighbor boids, all following the same three rules:
- Separation (collision avoidance): steer to avoid crowding local flockmates
- Alignment (velocity matching): steer towards the average heading of local flockmates
- Note: remember that a vector is a combination of a speed and a direction (heading)!
- Cohesion (flock centering): steer to move towards the average position (center of mass) of local flockmates
And here is what those rules look like when applied to a set of agents (boids):
| Separation | Alignment | Cohesion |
|---|---|---|
 |
 |
 |
Additional rules can be implemented to simulate specific behaviors like obstacle avoidance, predator-prey interactions, bait balls, and more.
Articles:
- Flocks, Herds, and Schools: A Distributed Behavioral Model - original 1987 paper by Craig Reynolds
- Boids on Wikipedia
- Chapter 6. Autonomous Agents from Nature of Code
- Boids by Craig Reynolds
Code projects:
- Boids (source) by Marcio Puga (JavaScript, PixiJS)
Videos:
- Coding Challenge #124: Flocking Simulation by Daniel Shiffman (Github repo with source code for p5.js and Processing)