# Windsurf Simulator A 3D browser game that teaches the **real mechanics of windsurfing**. You control the same levers a real windsurfer has — sheet angle, mast rake, foot stance, body lean, daggerboard, harness — and the board responds the way a real one would. No rudder, no arcade shortcuts: you steer by trimming the sail, you plane when the physics say you can, and you get catapulted when you get greedy with the power. **▶ Play it in your browser: ** It's a static, no-build web app (three.js + vanilla JS). Nothing to install to play — just open the link. Works on desktop and touch/mobile, in 20 UI languages. > ⚠️ It's a *learning toy*, not a certified trainer. The physics are a faithful simplification > meant to build intuition, not to replace time on the water.

## Run it locally Any static server works. From this directory: ```bash python3 -m http.server 8737 # open http://localhost:8737 ``` (Needs internet on first load — three.js is pulled from a CDN.) ## The physics it models | Real mechanic | In the game | |---|---| | Sail = airfoil; angle of attack controls lift | **Sheet slider** vs. the moving green "optimal trim" tick. Too far out → luffing (flaps, no power). Too far in → stall (heel force, no drive). | | Apparent wind swings forward as you accelerate | Optimal trim tick moves toward 0° as you speed up — you must keep sheeting in. Drive dies if the apparent wind reaches the bow (natural top speed). | | No rudder — steer by moving the sail's centre of effort | **Mast rake**: back → luff up (turn upwind), forward → bear away (turn downwind). | | No-go zone (~45° either side of the wind) | Sail cannot drive there; you stop and drift backwards ("in irons"). | | Sideways pull must be countered by the rider | **Windward lean** slider + balance meter. Too little lean vs. power → **catapult**. Too much lean when power dies → fall in backwards. | | Daggerboard resists leeway at low speed, but lifts violently at high speed | Down: little sideways drift. Up: you slip sideways when slow. Down **while planing** → spinout crash. | | Planing: above a speed/power threshold the hull skims and drag collapses | Reach ~8 kn with good power on a beam/broad reach → PLANING badge, big acceleration. Then you must move back into the straps or you'll pearl the nose. | | Harness carries the load but commits you | +38% effective lean, but gusts fling you faster if overpowered. Hooking in requires actual pull in the sail. | | Tacking / gybing | Scripted maneuvers with realistic entry conditions (tack needs speed + an upwind-ish course; gybe starts from a broad reach). Sailor switches sides. | | Gusts and wind shifts | True wind oscillates ±15% and wanders ±6°; watch the GUST indicator. | ## Controls | Input | Action | |---|---| | `W` / `S` | Sheet in / out | | `◀` / `▶` | Rake mast back (upwind) / forward (downwind) — momentary | | `Q` / `E` | Less / more windward lean | | `1` `2` `3` | Stance: front / neutral / back straps | | `D` | Daggerboard up/down | | `H` | Hook in/out of harness | | `T` / `G` | Tack / Gybe | | `R` | Reset | | Mouse drag / scroll | Orbit / zoom camera | Everything is also clickable in the right-hand panel. "Smart interlocks" refuse impossible combinations (hooking into a powerless sail, back straps with no speed, …) and explain why in the hint bar. ## Language **20 languages**: English, Українська, Deutsch, Français, Español, Italiano, Português, Nederlands, Polski, Čeština, Svenska, Dansk, Suomi, Ελληνικά, Türkçe, Bahasa Indonesia, Русский, 中文, 日本語, 한국어. The app picks your browser language on first load; the button in the bottom-left corner switches it, and the choice is remembered in `localStorage`. All strings live in `src/i18n.js` — add a language by adding another entry to `STRINGS`. English and Ukrainian are hand-written; the other 18 are AI-translated and not yet reviewed by native speakers, so corrections via pull request are very welcome. ## Files - `src/sim.js` — physics: apparent wind, sail lift curve, points of sail, planing, balance, crashes - `src/world.js` — three.js scene: sea shader, wind streaks, board/rig/sailor, splash & wake - `src/ui.js` — control panel, interlock rules, HUD meters, compass - `src/i18n.js` — translation tables (20 languages) + language toggle - `src/demo.js` — the guided auto-sailing demo tour - `src/main.js` — game loop ## Built with - [three.js](https://threejs.org/) (r160, via CDN) for the WebGL scene - Plain ES modules — **no build step, no bundler, no framework**. Edit a file, reload the page. - Deployed as static files on GitHub Pages. ## Contributing Issues and pull requests are welcome — especially: - **Translation fixes** for any of the 18 AI-translated languages (see `src/i18n.js`). - Physics tweaks that make a mechanic feel more true to life. There's no build to run; open `index.html` through any static server and edit. ## License Released under the [MIT License](LICENSE) — free to use, modify, and build on, including in commercial projects. The only condition is to keep the copyright notice. Do whatever you like with it; a mention is appreciated but not required. ## Author Made by **Viacheslav Mukha**, with help from Claude (Anthropic).