限界 · Genkai

Structural cross-sections, pushed to the limit.

Genkai (限界, "the limit") is a pure-Rust engine for structural cross-section analysis, exposed through a Python API and a desktop GUI.

It computes the geometric, elastic, plastic, and warping/torsion properties of arbitrary cross-sections (massive or thin-walled, with holes, single- or multi-material), and has grown into a reinforced and prestressed concrete (RC/PSC) section design and verification engine to the Eurocodes (EN 1992).

Why the name. In structural engineering, 限界状態 (genkai jōtai) is the limit state — the ultimate and serviceability limits that the whole of Eurocode design is built around. Every section this engine touches is checked against its limit. And もう限界 (mou genkai, "I'm at my limit") is, roughly, how it felt to name the thing. The name stuck for both reasons.

Status: pre-alpha. Phases 1–5 are shipped (geometry/elastic/plastic/warping replacing sectionproperties, multi-material, thin-wall shear/torsion, and an EN 1992 RC/PSC design engine); Phases 6 (EN 1992 conformance hardening) and 7 (design feature-parity) are outstanding. See the releases for shipped versions.

📖 Documentation: Theory book · Python API guide — pip install genkai.

Why

• Performance — a native, parallel Rust core (single sparse factorization reused across right-hand sides, GIL-free assembly) instead of interpreted Python.
• Independence — a fully owned, permissively licensed computation stack with no third-party analysis engine.
• Scope — multi-material sections and RC/PSC design to the Eurocodes, an area not covered by existing open tools.

Architecture

• crates/genkai-core — pure Rust computation core: geometry, meshing, finite-element warping, and section properties. No Python, no GUI.
• crates/genkai-py — PyO3 bindings exposing the genkai._genkai extension module.
• crates/genkai-gui — Tauri v2 desktop backend over the core (serde DTOs). The frontend lives in gui/ (React + Vite + TypeScript).
• python/genkai — the Python package surface.
• docs/theory — the theory manual (mdBook): derivations and validation references — read online.
• docs/api — the Python API guide (mdBook): how to drive the engine, with runnable examples — read online.

At a glance

import genkai

g = genkai.Geometry(outers=[[(0, 0), (100, 0), (100, 60), (0, 60)]])
sec = genkai.Section(g, material=genkai.Material("steel", 200e3, 0.3, 355, 7.85e-9))

geo = sec.geometric()                 # frozen results: .area, .ixx_c, .perimeter, …
solved = sec.analyze(mesh_size=5.0)   # mesh + warping solve, once
warp = solved.warping()               # .j, .cw, .x_se, …
stress = solved.stress(mxx=1e6, mzz=5e4)

Technology stack

Permissive licenses only, enforced in CI by deny.toml:

Build (developer)

Requires Rust (stable, MSRV 1.83). Building the GUI backend (crates/genkai-gui) additionally needs the frontend bundle, which Tauri embeds at compile time — build it first:

cd gui && npm ci && npm run build   # produces gui/dist (required by `cargo build --workspace`)
cd ..

Then the Rust workspace:

cargo build --workspace      # build the Rust core, bindings, and GUI backend
cargo test  --workspace      # run the Rust test suite
cargo deny  check            # license and advisory gate

The Python extension is built and installed into the active virtual environment with maturin — the recommended developer loop:

maturin develop              # build + install `genkai` (editable) into the active venv
pytest python/tests          # run the Python test suite

To rebuild the extension manually without maturin, build the crate and copy the artifact next to the package using the name for your platform:

cargo build -p genkai-py
# Linux:    cp target/debug/lib_genkai.so   python/genkai/_genkai.so
# macOS:    cp target/debug/lib_genkai.dylib python/genkai/_genkai.so
# Windows:  copy target\debug\_genkai.dll    python\genkai\_genkai.pyd

License

Genkai is licensed under the Apache License 2.0. You are free to use, modify, and distribute it, including for commercial purposes, provided you retain the copyright and NOTICE attribution as required by the License.

Citation

If you use Genkai in academic, professional, or commercial work, please cite it. GitHub renders a "Cite this repository" button from CITATION.cff; attribution in any derived product, publication, or report is requested.