Cross-platform GPU multiphysics simulation

/!\ This library is still under heavy development and is still missing many features.

The goal of nexus is to essentially be "rapier on the GPU". It aims to be a cross-platform GPU-accelerated multiphysics engine, running compute shaders via WebGPU. Shaders are written in Rust using Rust-GPU and compiled to SPIR-V.

Physics modules

Nexus is organized into independent physics modules, each available in 2D and 3D:

nexus_rbd - Rigid-body dynamics: colliders (boxes, balls, capsules, cones, cylinders, convex shapes, polylines, trimeshes), joints (ball, fixed, prismatic, revolute), contact resolution.
nexus_mpm - Material Point Method: a hybrid particle/grid-based method for simulating deformable objects, granular materials, fluids, etc. Supports one-way coupling with rigid-bodies (= rigid-bodies can push particles but particles cannot push rigid-bodies).

Rigid-body friction (3D)

Choose the contact model globally with RbdSimParams::friction_model:

use nexus_rbd3d::dynamics::{FrictionModel, RbdSimParams};

let params = RbdSimParams {
    friction_model: FrictionModel::Simplified,
    ..RbdSimParams::default()
};

Coulomb (the default) solves sliding friction at each contact point. Simplified follows Rapier's twist-friction model: per-point normal constraints, one sliding-friction constraint at the manifold center, and one angular constraint resisting twist about its normal. A single-point contact has no twist constraint. The models approximate friction differently and can produce different motion. Multibody contacts always use Coulomb, as in Rapier; 2D is unchanged.

Pass these parameters to RbdState::from_rapier (identically for every environment), or call NexusState::set_rbd_friction_model before finalize. A live RbdState can switch all environments with set_friction_model(&backend, model). Switching keeps the body poses and velocities but resets every contact warmstart.

Prerequisites

Install `cargo gpu`

Nexus uses cargo gpu to compile its Rust-GPU shaders to SPIR-V during the build. You must install it before building, otherwise the shader compilation step will fail:

cargo install cargo-gpu --version 0.10.0
cargo gpu install # Install the toolchain needed by cargo-gpu

For building running on the browser:

rustup target add wasm32-unknown-unknown
cargo install wasm-server-runner

WebGpu might not be enabled on your browser:

It is often already enabled by default on Windows and Macos major browsers.
On Firefox, go to about:config then set dom.webgpu.enabled to true.
On chromium, go to chrome://flags then set Unsafe WebGPU Support to Enabled. Keep in mind that, on Ubuntu, we observed WebGPU performances to be significantly worse on chromium compared to Firefox.
Safari is currently not supported by Nexus.

Running the examples

The example binaries launch a viewer window with all available demos. Use the --release flag for good performance, as debug builds of GPU physics code will be very slow.

# Run natively
cargo run --release --bin all_examples3
cargo run --release --bin all_examples2
# Run on the browser
cargo run --release --bin all_examples3 --target wasm32-unknown-unknown
cargo run --release --bin all_examples2 --target wasm32-unknown-unknown

Python bindings

The 3D engine and viewer are also available from Python as the nexus3d module (PyO3 + maturin), mirroring the Rust API closely. See crates/nexus_python3d/README.md for building instructions and a full set of example scripts (rigid bodies, joints, and URDF/MJCF robots).

License

MIT OR Apache-2.0

Name		Name	Last commit message	Last commit date
.cargo		.cargo
.github/workflows		.github/workflows
.run		.run
assets		assets
crates		crates

Latest commit

History

Folders and files