null0go

A WASM-based game engine for Go, where games ("carts") are loaded as zip files containing main.wasm.

Part of the null0 project.

I am playing with a few go-ideas here:

• host made in go. I dunno if I will finish this, but want to play with the idea of using ebiten/wazero/merged_fs, since it's simpler than the C counterparts
• carts made with tinygo. This idea will probably stick around.
• codegen for host & carts, written in go

Quick Start

# Install dependencies (requires go & tinygo)
make setup

# Build the host runtime
make null0

# Build example carts
make carts

# Run a cart
./host/null0 hello.null0

The host merges carts and directories into a single filesystem, so you can test a directory with main.wasm, or give a cart access to any directories you want:

./host/null0 hello.null0 someassets/

this makes it so main.wasm in hello.null0 has access to all the files in someassets/, as if they were in the cart.

Usage

Here is a quick usage-example (go cart)

import null0 "github.com/notnullgames/null0go/cartapi"

func main() {
  null0.Clear(null0.RED)

  if null0.KeyDown(null0.KEY_SPACE) {
      println("Space pressed!")
  }

  points := []null0.Vector{
      {X: 10, Y: 10},
      {X: 50, Y: 50},
      {X: 10, Y: 50},
  }

  null0.DrawPolygon(null0.BLUE, 3, points)
  img := null0.LoadImage("player.png")
}

You can also export callbacks. See callbacks cart.

Code Generation

The entire API is defined in YAML files under api/. Run the code generator with:

make codegen

Warning

This stubs the host-code, and will wipe it!

This generates:

1. cartapi/null0.go - Go package with types, enums, and //go:wasmimport null0 <func> declarations
2. host/null0_api.go - Host-side function stubs (currently just prints debug messages)

The generator converts snake_case function names to PascalCase for Go exports (e.g., delta_time → DeltaTime), while preserving the original names in the wasmimport directives (so it will work with carts/host already made in other languages.)