Unity and Rust Tutorial

In this tutorial, we will compile Rust to WebAssembly and run it in Unity.

WaaS can import WebAssembly modules, but you can also import Rust files directly and compile them into WebAssembly modules on the spot.

1. Install Rust toolchain and add the wasm32-unknown-unknown target.

rustup target add wasm32-unknown-unknown

2. Install WaaS in your Unity project.

3. Create main.rs in your Unity project:

#[no_mangle]
pub extern "C" fn add(a: i32, b: i32) {
    a + b
}

4. Create a C# script Test.cs that runs the add() function:

using System;
using UnityEngine;
using WaaS.Runtime;
using WaaS.Unity;

public class Test : MonoBehaviour
{
    [SerializeField] private ModuleAsset moduleAsset; // imported main.rs

    private void Start()
    {
        // Load the module
        var module = moduleAsset.LoadModule();

        // Instantiation
        var instance = new Instance(module, new Imports());

        // Get the exported function
        var function = instance.ExportInstance.Items["add"] as IInvocableFunction;

        // Create ExecutionContext
        using var context = new ExecutionContext();

        // Invocation
        var result = CoreBinder.Instance.Invoke<int>(function, 1, 2);

        Debug.Log($"Completed: 1 + 2 = {result}"); // Completed: 1 + 2 = 3
    }
}

5. Attach Test.cs to a GameObject in your scene and assign ModuleAsset to the script.

> Completed: 1 + 2 = 3