cgal-pycad 0.1.0

A Python library for exact 3D geometric modeling using CGAL

CGAL PyCAD

CGAL PyCAD is a Python library for exact 3D geometric modeling, built on top of the powerful CGAL library. It provides a simple, OpenSCAD-like Domain Specific Language (DSL) for creating constructively solid geometry (CSG) without the floating-point errors common in other CAD tools.

Features

• Exact Arithmetic: All coordinates are handled as exact rational numbers (CGAL::Gmpq), ensuring zero precision loss during booleans and transformations.
• Robust Backend: Powered by CGAL's Nef_polyhedron_3, guaranteeing valid, closed 3D solids.
• Pythonic wrappers: Simple, functional API inspired by OpenSCAD.
• No Floating Point: The API strictly accepts integers, fractions.Fraction, or rational strings/tuples. Floats are explicitly forbidden to prevent accidental precision loss.
• Export: Generates standard STL and OFF files for 3D printing and visualization.

Installation

Prerequisites

You must have CGAL and a C++ compiler installed on your system.

Ubuntu/Debian:

sudo apt update
sudo apt install libcgal-dev g++ cmake

From PyPI (Coming soon)

pip install cgal_pycad

From Source

git clone https://github.com/ctrichet/cgal_pycad.git
cd cgal_pycad
pip install .

Usage

from cgal_pycad import cube, translate, scale
from fractions import Fraction

# Create a base block (100 x 200 x 2)
base = cube([100, 200, 2])

# Create a slot
slot = cube([10, 3, 4])

# Subtract slot from base multiple times
for i in range(5):
    # exact translation
    t_vec = [20*i, -1, -1]
    base = base - translate(t_vec)(slot)

# Scale (anisotropic)
result = base.scale([1, 1, Fraction(1, 2)])

# Export
result.to_stl("output.stl")

Contributing

Contributions are welcome!

1. Fork the repository.
2. Create your feature branch (git checkout -b feature/amazing-feature).
3. Commit your changes.
4. Push to the branch.
5. Open a Pull Request.

Development Setup

# Create venv
python3 -m venv venv
source venv/bin/activate

# Install build deps
pip install scikit-build cmake ninja pybind11

# Build and install in editable mode
pip install -e .

License

Distributed under the MIT License. See LICENSE for more information.