notnull games

• Template: cart_onyx - press "Use this template" and you have a working game.
• Docker image: ghcr.io/notnullgames/null0-cart-onyx:latest
• Your code: cart/main.onyx, compiled with onyx
• Bindings: carts/onyx/null0.onyx (baked into the docker image for you)
• WASI is available, so ordinary file and stdio calls work.
• See carts made with Onyx
• API docs for Onyx

building

You do not install onyx - the docker image has it, and the current null0 bindings, baked in. There is nothing in your project to keep in sync with the engine.

docker run --rm --user $(id -u):$(id -g) \
  -v ./cart:/src -v ./webroot:/out \
  ghcr.io/notnullgames/null0-cart-onyx:latest mygame

The template wraps that in npm start, which also serves the result and rebuilds when you save.

Onyx notes

• #load "null0.onyx", and keep an empty main around.
• Text takes a u32 pointer, not a str - onyx cannot alias a foreign import name, so wrap literals with cstr("...") from the bindings.

a cart, in Onyx

This is carts/onyx/simple/main.onyx in the engine repo - the same file CI builds into the cart below, so it always compiles.

#load "null0.onyx"

// onyx needs a main, even though null0 never calls it
main :: () {}

load :: () {
    clear(BLUE);
    draw_circle(100, 100, 50, RED);
    // a string crosses as a pointer to null-terminated utf8; cstr() from the
    // bindings does that conversion
    draw_text(FONT_DEFAULT, cstr("hello from Onyx"), 170, 92, WHITE);
}

#export "load" load

// callbacks (optional - implement as needed)
//
//   update :: () {}
//   #export "update" update

This toolchain needs an entry point to exist even though null0 never uses it for gameplay. Leave it empty: main :: () {}

callbacks

A cart implements the callbacks it cares about. In Onyx they look like this:

#export "load" load

See anatomy of a cart for the full list and what each one is passed.