Bevy WASM

Mod your Bevy games with WebAssembly!

bevy_wasm		For games
bevy_wasm_sys		For mods
bevy_wasm_shared		For protocols

See examples/cubes for a comprehensive example of how to use this.

Changelog

Protocol

Our protocol crate defines the two message types for communicating between the game and mods.

[dependencies]
bevy_wasm_shared = "0.10"
serde = { version = "1.0", features = ["derive"] }

use bevy_wasm_shared::prelude::*;
use serde::{Deserialize, Serialize};

/// The version of the protocol. Automatically set from the `CARGO_PKG_XXX` environment variables.
pub const PROTOCOL_VERSION: Version = version!();

/// A message to be sent Mod -> Game.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ModMessage {
    Hello,
}

/// A message to be sent Game -> Mod.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum GameMessage {
    HiThere,
}

Game

Our game will import WasmPlugin from bevy_wasm, and use it to automatically send and receive messages with the mods.

[dependencies]
bevy = "0.10"
bevy_wasm = "0.10"
my_game_protocol = { git = "https://github.com/username/my_game_protocol" }

use bevy::prelude::*;
use bevy_wasm::prelude::*;
use my_game_protocol::{GameMessage, ModMessage, PROTOCOL_VERSION};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugin(WasmPlugin::<GameMessage, ModMessage>::new(PROTOCOL_VERSION))
        .add_startup_system(add_mods)
        .add_system(listen_for_mod_messages)
        .add_system(send_messages_to_mods)
        .run();
}

fn add_mods(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn(WasmMod {
        wasm: asset_server.load("some_mod.wasm"),
    });
    commands.spawn(WasmMod {
        wasm: asset_server.load("some_other_mod.wasm"),
    })
}

fn listen_for_mod_messages(mut events: EventReader<ModMessage>) {
    for event in events.iter() {
        match event {
            ModMessage::Hello => {
                println!("The mod said hello!");
            }
        }
    }
}

fn send_messages_to_mods(mut events: EventWriter<GameMessage>) {
    events.send(GameMessage::HiThere);
}

Mod

Our mod will import FFIPlugin from bevy_wasm_sys, and use it to automatically send and receive messages with the game.

[dependencies]
bevy_wasm_sys = "0.10"
my_game_protocol = { git = "https://github.com/username/my_game_protocol" }

use bevy_wasm_sys::prelude::*;
use my_game_protocol::{GameMessage, ModMessage, PROTOCOL_VERSION};

#[no_mangle]
pub unsafe extern "C" fn build_app() {
    App::new()
        .add_plugin(FFIPlugin::<GameMessage, ModMessage>::new(PROTOCOL_VERSION))
        .add_system(listen_for_game_messages)
        .add_system(send_messages_to_game)
        .run();
}

fn listen_for_game_messages(mut events: EventReader<GameMessage>) {
    for event in events.iter() {
        match event {
            GameMessage::HiThere => {
                println!("The game said hi there!");
            }
        }
    }
}

fn send_messages_to_game(mut events: EventWriter<ModMessage>) {
    events.send(ModMessage::Hello);
}

Sharing Resources

Protocol:

#[derive(Resource, Default, Serialize, Deserialize)]
pub struct MyResource {
    pub value: i32,
}

Game:

App::new()
    ...
    .add_resource(MyResource { value: 0 })
    .add_plugin(
        WasmPlugin::<GameMessage, ModMessage>::new(PROTOCOL_VERSION)
            .share_resource::<MyResource>()
    )
    .add_system(change_resource_value)
    ...

fn change_resource_value(mut resource: ResMut<MyResource>) {
    resource.value += 1;
}

Mod:

App::new()
    ...
    .add_plugin(FFIPlugin::<GameMessage, ModMessage>::new(PROTOCOL_VERSION))
    .add_startup_system(setup)
    .add_system(print_resource_value)
    ...

fn setup(mut extern_resource: ResMut<ExternResources>) {
    extern_resources.insert::<MyResource>();
}

fn print_resource_value(resource: ExternRes<MyResource>) {
    println!("MyResource value: {}", resource.value);
}

See examples/shared_resources for a full example.

Roadmap

✅	wasmtime runtime in games
✅	Send messages from mods to game
✅	Send messages from game to mods
✅	Multi-mod support
✅	Time keeping
✅	Protocol version checking
✅	Extern Resource
✅	Startup system mod loading
✅	Direct update control
✅	Mod unloading
✅	Mod discrimination (events aren't broadcast all)
✅	Browser support
⬜	Extern Query
⬜	Synced time
⬜	Mod hotloading
⬜	Automatic component syncing

License

Bevy WASM is free, open source and permissively licensed! Except where noted (below and/or in individual files), all code in this repository is dual-licensed under either:

• MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)
• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

at your option. This means you can select the license you prefer! This dual-licensing approach is the de-facto standard in the Rust ecosystem and there are very good reasons to include both.

Your contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.