Bevy GGRS

Bevy plugin for the GGRS P2P rollback networking library. Handles advancing game state and rollbacks via a dedicated schedule, snapshotting only the components and resources you register.

Quickstart

# Cargo.toml
[dependencies]
bevy_ggrs = { git = "https://github.com/gschup/bevy_ggrs" }

use bevy::prelude::*;
use bevy_ggrs::prelude::*;

type GgrsConfig = bevy_ggrs::GgrsConfig<u8>; // replace u8 with your input type

App::new()
    .add_plugins(GgrsPlugin::<GgrsConfig>::default())
    .insert_resource(RollbackFrameRate(60))
    // register components/resources for snapshotting
    .rollback_component_with_clone::<Transform>()
    // provide inputs each frame
    .add_systems(ReadInputs, read_local_inputs)
    // your game logic — must be deterministic!
    .add_systems(GgrsSchedule, move_players)
    .insert_resource(Session::SyncTest(session))
    .run();

// #[require(Rollback)] ensures Rollback is always added with Player —
// no need to include it manually in every spawn call.
#[derive(Component)]
#[require(Rollback)]
struct Player;

fn spawn_player(mut commands: Commands) {
    commands.spawn((Transform::default(), Player));
}

For full P2P and spectator session examples, see examples/. For guides on writing correct rollback systems, see docs/pitfalls.md and docs/debugging-desyncs.md. For an overview of how bevy_ggrs works internally, see docs/architecture.md.

Live Demonstration (unmaintained)

bevy_ggrs has a demo app using matchbox for browser-based P2P. It is currently unmaintained and may not work with the latest version.

• Demo Repository

Compatible Versions

bevy	bevy_ggrs	ggrs
0.18	main	main
0.18	0.20	0.11.1
0.17	0.19	0.11.1
0.16	0.18	0.11.1
0.15	0.17	0.11.0
0.14	0.16	0.10.2
0.13	0.15	0.10.1
0.12	0.14	0.10
0.11	0.13	0.9.4
0.10	0.12	0.9.4
0.9	0.11	0.9.3
0.8	0.10	0.9
0.6	0.9	0.9

Community

• matchbox — WebRTC socket layer, pairs well with bevy_ggrs for browser/WASM P2P
• extreme_bevy — tutorial and example project: how to build a low-latency P2P web game with bevy_ggrs and matchbox

Thanks

to bevy_backroll and bevy_rollback for figuring out pieces of the puzzle that made bevy_ggrs possible. Special thanks to the helpful folks in the Bevy Discord for their support along the way.

Licensing

Bevy_GGRS is dual-licensed under either

• MIT License: Also available online
• Apache License, Version 2.0: Also available online

at your option.