Boids Aquarium

A little society, behind glass.

Not another flocking demo. These boids pair up and drift apart, raise families, grow old, catch epidemics, evolve their colours and get hunted — a whole population living and dying while you watch. The classic boids model gives you graceful motion; Boids Aquarium keeps that underneath and builds an entire population biology on top.

▶ Live demo: ubrowz.github.io/boids-society

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Most boids simulations are a swarm. This one is a society.

On top of cohesion / alignment / separation, every number you see is a living demographic:

• Bonds & families — boids marry, raise offspring, and divorce.
• Birth, age & death — populations grow, age on a Gompertz survival curve, and die back.
• Genetics — colour is the genome; a shared gene pool evolves, with inbreeding depression.
• Epidemics — a contagious disease spreads on an R number and can wipe out a crowd.
• Predation — predators hunt with an agenda (bump or lock strategies).
• Depth — an optional 2.5D z-range with continuous depth sorting.

Under the hood the flock uses a conservative cohesion spring (centre-of-mass preserving, so clusters breathe and roam instead of creeping into a corner) plus Boltzmann rotational diffusion — a thermal "temperature" that keeps the swarm mixing.

Try it

• Open the live site — landing page, with an embedded live simulation ("Run it live").
• Open the dashboard — the full control panel: dozens of sliders (speed, sensing, cohesion, temperature, populations, genetics, disease, predators, image scale), toggles, Save/Load presets, and video recording. Steer the aquarium live in its own tab, or export a standalone copy.
• Read the field guide — an illustrated guide to the creatures and their world.
• About / colophon

Run it locally

No build, no server, no dependencies — it's plain HTML:

git clone https://github.com/ubrowz/boids-society.git
cd boids-society
open index.html          # or double-click it, or serve the folder statically

Everything (including the PixiJS engine and fonts) is embedded, so it runs fully offline.

How it's built

• Rendering: PixiJS v7 (WebGL), embedded inline — no CDN fetch.
• Effects & overlays: Canvas 2D (trails, tails, beaks, bond lines, birth/death FX).
• Language: vanilla JavaScript — no framework, no build step.
• Delivery: each screen is a single self-contained .html file.

The dashboard has three run modes: a dashboard (controls only), a live tank (opened in its own tab and steered live from the dashboard), and a standalone export — a UI-less, auto-starting kiosk build that runs fullscreen and fully offline in any WebGL browser.

Repo layout

File	What it is
index.html	Landing page (with embedded live demo)
about.html	Colophon / credits
boid-world-field-guide.html	Illustrated field guide to the boid world
pics-anim-pi-pixi.html	The main app — PixiJS dashboard + live aquarium + exporter
boids-society.html	An exported standalone build (kiosk / embed)
pics-anim-pi-design.html	Design & implementation notes for the main app

Other files in the repo are earlier Canvas-2D iterations and design notes kept for reference.

License

MIT © 2026 Joep Rous.

Questions or ideas? Open an issue or find me at @ubrowz.