#gamedev #bevy


Rollback safe utilities and abstractions for Bevy

1 unstable release

0.1.0 Nov 14, 2023

#1702 in Game dev

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76 lines


crates.io MIT/Apache 2.0 docs.rs

Rollback-safe implementations and utilities for Bevy Engine.


Some of Bevy's features can't be used in a rollback context (with crates such as bevy_ggrs). This is either because they behave non-deterministically, rely on inaccessible local system state, or are tightly coupled to the Main schedule.


  • States
  • FrameCount
  • Events


Bevy states when added through app.add_state::<FooState>() have two big problems:

  1. They happen in the StateTransition schedule within the MainSchedule
  2. If rolled back to the first frame, OnEnter(InitialState) is not re-run.

This crate provides an extension method, add_roll_state::<S>(schedule), which lets you add a state to the schedule you want, and a resource, InitialStateEntered<S> which can be rolled back and tracks whether the initial OnEnter should be run (or re-run on rollbacks to the initial frame).

See the states example for usage with bevy_ggrs.

Cargo features

  • bevy_ggrs: Enable integration with bevy_ggrs
  • math_determinism: Enable cross-platform determinism for operations on Bevy's (glam) math types.

Bevy Version Support

bevy bevy_roll_safe
0.12 0.1, main


bevy_roll_safe is dual-licensed under either

at your option.


PRs welcome!


~405K SLoC