---
jupyter:
  description: Build planex2d from source with CMake and scikit-build-core, run its
    tests, and contribute.
---

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# Building and contributing

planex2d is a C++20 library with Python bindings (pybind11), built with CMake through scikit-build-core. The sources
are at <https://github.com/planex2d/planex2d>.

## Requirements

- a C++20 compiler (GCC, Clang or MSVC) and CMake 3.20 or newer;
- Python 3.11 or newer;
- netgen and the OpenCASCADE headers, which by default come from the pip packages of the Python that builds, so that
  no OpenCASCADE installed elsewhere on the system is picked up;
- optionally `ccache`, which is used automatically when found.

Eigen and Taskflow are included in `external_dependencies/`; pybind11 comes with the netgen-mesher package.

## Build

```bash
git clone https://github.com/planex2d/planex2d
cd planex2d
pip install netgen-mesher netgen-occt-devel scikit-build-core
pip install --no-build-isolation -e .
```

The editable install rebuilds the C++ part on the next `import planex` after a source change. Two settings change the
build:

- `NETGEN_CMAKE_DIR=/path/to/netgen/cmake` builds against another netgen, for example a netgen built from source;
- `-Ccmake.define.PLANEX_CONSTRAINTS=OFF` builds without the constraint sketch and its solver, so `px.Sketch` is then
  missing, while `px.QuickSketch` remains.

## Tests

```bash
pip install pytest hypothesis shapely
pytest tests
```

The randomized fuzz tests share a time budget of 30 seconds, and `--fuzz-seconds 600` gives them more. See
[Testing](testing.md) for how planex2d is tested.

## Contributing

Bugs and changes go through the issues and pull requests of the repository. A change comes with tests for what it
fixes or adds, and the whole test suite passes before it is merged.
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