// the find
appsinacup/godot-rapier-physics
Godot Rapier Physics – 2D and 3D physics engine for the Godot game engine. with better stability, performance, liquids, determinism, state serialization and no ghost collisions.
A GDExtension that replaces Godot 4's built-in physics servers (both 2D and 3D) with the Rapier physics engine, written in Rust via godot-rust. The main reasons to reach for it over stock Godot physics are determinism, fluid simulation via Salva, and the elimination of ghost collisions on fast-moving bodies.
State serialization is a first-class feature — you can snapshot and restore the entire physics world, which is genuinely hard to do with Godot's built-in engine and valuable for rollback netcode or save-state replays. The cross-platform determinism mode (enhanced-determinism feature flag) gives you bit-exact simulation across platforms, not just within one machine — that's a rare guarantee in game physics. The CI matrix is thorough: separate workflows for Linux, Windows, macOS, iOS, Android, and Emscripten web builds, plus dedicated determinism and compatibility checks. The plugin ships prebuilt binaries via the Godot Asset Store, so most users never touch the Rust toolchain.
The 3D implementation is explicitly incomplete — the progress page exists precisely because there are known gaps, and adopting it for a 3D game means auditing what's missing before shipping. Asymmetric collision masks are not supported: the engine ORs both layers together, so you cannot have object A hit B without B hitting A, which breaks common game patterns like one-way damage zones. Double-precision builds must be compiled manually — there's no prebuilt double variant despite double being the right choice for large open worlds. Bundling this with another GDExtension crate requires non-trivial boilerplate (forwarding init stages, setting env vars) and the docs warn clearly that loading both the standalone addon and the crate in the same project will double-register classes and break things.