Flocking

Boids: three local rules, and a murmuration emerges. Chase it with a hawk.

0/2challenges

Hawk follows pointer

Wrap edgesTrails

Separation

Alignment

Cohesion

Visionpx

Top speedpx/s

Birds

Order parameter: 0.00
Birds: 350
Typical neighbours in view: 7

The model

Craig Reynolds' boids, from 1986. Every bird follows three local rules about the neighbours it can see: steer away from ones that are too close (separation), match their average heading (alignment), and drift towards their centre (cohesion).

No bird knows the shape of the flock, yet flocks, schools and swirls emerge. The order parameter on the chart is 1 when everyone flies the same way and close to 0 when headings are random.

Try this

Turn on the hawk and chase the flock with your pointer: watch it split and reform. Set alignment to zero and the flock falls apart; raise cohesion alone and you get a buzzing swarm.

Two-dimensional, instantaneous reactions and a fixed field of view all the way round. Educational model, not an engineering design or validation tool.

Achievements0/2

In formation +30Get 200 or more birds to an order of 0.95.
Bird of prey +20Chase the flock with the hawk for ten seconds.

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