Boids

Boids is a computer simulation of flocking behavior in which a collection of simple autonomous agents, called boids, move through space and interact with only nearby neighbors. Developed by Craig W. Reynolds and presented in 1987, the model aimed to produce realistic group motion without explicit global coordination. Although inspired by bird flocks, Boids models abstract individual birds as points with velocity, enabling fast, scalable simulations for animation and artificial life research.

Each boid follows three steering rules: separation to avoid crowding, alignment to align velocities with neighbors, and cohesion to move toward the local neighborhood's center of mass. These rules are applied based on a perception radius, so behavior is purely local. By weighting and combining the three steering vectors, a boid adjusts its velocity and position.

The emergent flocking behavior results from simple local interactions, allowing large groups to exhibit cohesive, fluid motion. Variants add obstacle avoidance, goal seeking, or noise to simulate turbulence. Realistic results depend on parameter choices such as neighborhood size, force weights, and speed limits.

Applications include computer animation, visual effects, game development, virtual environments, and robotics research. Boids is widely cited as an early example of emergent behavior and agent-based modeling.