A koi pond seen from above, where the fish swim like fish: each one is a spine of fourteen points following its head, with a swim wave that grows toward the tail, so the head stays steady and the tail does the work. They steer clear of each other and of the banks, and now and then one rises and leaves a ripple. The water is a shader laid over a painted pond floor, bending the view with swell and ripples, pooling caustics on the bottom, and glinting with a low sun or the moon.
Each koi is simulated, not animated. A spine of fourteen points follows the head, with a swim wave applied on top that grows toward the tail. Soft steering keeps the fish apart and off the banks, and every fish has its own size, pattern and depth — the deeper ones are murkier and fainter.
Self-hosted, read-only container. Koi makes no outbound request at all, ever — every fish and every frame is computed in the browser. Because nothing is fetched, it can also be built as a pure-static site for any CDN or file host.
A time of day — day, dusk, or night — and, if you like, a fish count and a seed. Everything scales from the screen’s own shorter side, so the same URL works on a 16:9 panel, a portrait tablet, or a phone.
Setup
A browser is genuinely enough — the Mac app and Fully Kiosk below are conveniences, not requirements.
F11 on Windows and Linux, ⌃⌘F on macOS.chrome --kiosk <url> — on macOS, open -a "Google Chrome" --args --kiosk <url>.Displays are ordinary web pages, so anything that can hold one open works: a Raspberry Pi on a monitor, a retired iPad, a Fire tablet, the browser built into a TV.
Configuration
Everything below, plus a live preview and a URL builder that writes the link for you, is at koi.livingkiosk.com/setup.
| Parameter | Default | Meaning |
|---|---|---|
koi | 7 | How many fish are in the pond, 1–24. |
speed | 1 | A multiplier on how fast everything moves, 0.2–3. Clamped, not rejected. |
pads | 6 | How many lily pads float on the surface, 0–16. Some carry a blossom. 0 leaves open water. |
petals | on | on or off. Blossom petals that drift down and land on the water, each leaving a small ripple. |
time | day | day, dusk, or night. Dusk is warm with the low sun on the water; night is dark and blue, with the moon. |
dim | 0 | Neutral darkening overlay, 0–0.8 (fleet-wide convention). |
seed | — | Pins which fish, where they start, and where the pads and pebbles lie, so the same URL always begins the same way. |
Koi is open source under the MIT licence. Run it yourself with one command. The source opens to the public soon.