gasm-sdk

Rust SDK for writing games for gasm, a portable game runtime on WebAssembly. A game compiles to one .wasm file that runs in the native runner (wasmtime + wgpu), in the browser (WebGPU), and headless in CI, bit-identically.

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

[dependencies]
gasm-sdk = "0.15"

use gasm::Buttons;

struct Hello { t: u32 }

impl gasm::Game for Hello {
    fn init() -> Result<Self, String> {
        gasm::set_frame_rate(60.0);
        Ok(Hello { t: 0 })
    }
    fn frame(&mut self) {
        if gasm::pad(0).held(Buttons::A) { gasm::log!("A at frame {}", self.t); }
        self.t += 1;
    }
}

gasm::game!(Hello);

cargo build --release --target wasm32-unknown-unknown
gasm-run target/wasm32-unknown-unknown/release/hello.wasm

What's in it:

Core: logging, time, frame rate, launch params, RGBA video, audio, four virtual gamepads, assets of any size (asset_size, asset_read_at with u64 offsets), and has(name) to ask whether the runner provides an import.
input, keys: raw keyboard, pointer, gamepads and joysticks.
gfx: a WebGPU subset with WGSL shaders and JSON descriptors; gfx::destroy frees objects.
gles: the OpenGL ES 3.0 C API on gasm:gl (gles::get_proc_address), for glow with the gasm fork patched in ([patch.crates-io] glow = { git = "https://github.com/emdzej/gasm" }), so glow-based crates such as egui_glow run unchanged.
net: WebSocket-style messages; fetch: HTTP requests made by the runner.
clipboard: copy text, read what the player pastes; files: save files for the player (pictures, exports).
manifest!: embed the capabilities manifest (requires, hosts, files), which runners check and ask about before the game starts.
storage: per-game saves; storage::try_set says why a write failed (storage::Error: Key, Size, Quota, Io).
main_loop!: for games with their own loop (main_loop!(run), or main_loop!(run, on_exit) to export gasm_exit too), with Binaryen's Asyncify. Games using game! don't carry its export or imports.
thread, sync: cooperative threads for threaded_main_loop! games (thread::spawn, Mutex, Condvar, Semaphore), deterministic: one wasm thread, switched with Asyncify.
Native builds: on non-wasm targets the crate links an in-process stub host (gasm::native), so the same game builds natively for debugging and parity tests.

The crate is gasm-sdk; the library is named gasm, so code says use gasm::…. Guide: Writing games · ABI: spec. The raw bindings (gasm::sys) are generated from spec/abi.json.

MIT licensed.

gasm-sdk 0.15.0

gasm-sdk