# Rust

Compile Rust games to WebAssembly and wire the Wavedash SDK from Rust.

Source: https://docs.wavedash.com/engines/rust

<GithubLink href="https://github.com/wvdsh/examples/tree/main/example-rust" />
<PlaytestLink href="https://wavedash.com/playtest/rust-example/a60eebb0-6194-4ffc-8d47-c1a73e07e699" />

Rust compiles to WebAssembly via the `wasm32-unknown-unknown` target. The output is a `.wasm` binary loaded by a hand-written JavaScript entrypoint (`web/game.js`).

## Setup

Install the WASM target:

```bash
rustup target add wasm32-unknown-unknown
```

Your crate should be a `cdylib`:

```toml
[lib]
crate-type = ["cdylib"]
```

## SDK integration

Declare the two Wavedash SDK functions as extern imports. Wavedash injects `Wavedash` into the page, and `web/game.js` bridges them into the WASM `env` namespace:

```rust
// src/lib.rs
unsafe extern "C" {
    fn wavedash_init();
    fn wavedash_update_progress(p: f32);
}

#[unsafe(no_mangle)]
pub extern "C" fn wd_init(width: f32, height: f32) {
    // ... game setup ...

    unsafe {
        wavedash_update_progress(1.0);
        wavedash_init();
    }
}
```

Call `wavedash_update_progress(...)` with intermediate values during async asset loading. `wavedash_init()` automatically signals load completion, so call it last.

On the host side, `web/game.js` provides the implementations:

```javascript
const Wavedash = window.Wavedash;

const imports = {
  env: {
    wavedash_init() { Wavedash.init({ debug: true }); },
    wavedash_update_progress(p) { Wavedash.updateLoadProgressZeroToOne(p); },
    // ...your other imports (draw primitives, score updates, etc.)...
  }
};

const response = await fetch("./game.wasm");
const bytes = await response.arrayBuffer();
const result = await WebAssembly.instantiate(bytes, imports);
```

## Build script

```bash
#!/usr/bin/env sh
set -eu
cargo build --lib --target wasm32-unknown-unknown --release

mkdir -p build/web
cp target/wasm32-unknown-unknown/release/game.wasm build/web/game.wasm
cp web/game.js  build/web/game.js
cp web/index.html build/web/index.html
```

## wavedash.toml

```toml
game_id = "YOUR_GAME_ID_HERE"
upload_dir = "./build/web"
```

## Other SDK features

Once initialized, `Wavedash` also exposes leaderboards, achievements, stats, and user data. Bridge these the same way -- declare additional `extern "C"` imports in Rust and provide implementations in `web/game.js` that call `Wavedash.uploadLeaderboardScore(...)`, `Wavedash.setAchievement(id, true)`, and `Wavedash.getUser()`. See the [SDK reference](/sdk/overview) for the full API.