planex2d 0.1.0

Fast, exact 2D geometry for Python
Documentation · Installation · Examples · License and notices

planex2d is free software under the GNU Lesser General Public License, version 2.1 or (at your option) any later version. Its compiled module contains code from Eigen, pybind11 and Taskflow, and it is linked to Netgen and Open CASCADE Technology; see License and notices and THIRD_PARTY_NOTICES.md. planex2d makes use of facilities provided by the Open CASCADE Technology software.

What it is

planex2d is a 2D geometry kernel for Python, written in C++. You draw outlines from lines, arcs, circles and splines, combine them with exact Boolean operations, dimension them with constraints, and clean up drawings imported from other tools. The resulting faces go to OpenCASCADE, netgen/NGSolve, gmsh and other tools for 3D modeling, meshing and simulation.

Installation

pip install netgen-mesher netgen-occt-devel scikit-build-core
pip install --no-build-isolation planex2d

Version 0.1 has no prebuilt wheels yet, so pip builds planex2d from source against netgen's OpenCASCADE: the first line installs netgen, the OpenCASCADE headers and the build backend, and the second builds without build isolation so that the build uses them. The build needs a C++20 compiler and CMake. The package is called planex2d on PyPI and planex in Python (import planex as px). See Installation for the optional packages.

A first sketch

A QuickSketch draws with a pen: Line draws along the current direction, Turn changes the direction, Arc continues with a tangent arc, and Close joins the outline to its start. Circle adds a hole. The result is an angle bracket with an inner fillet and two holes.

import planex as px

bracket = px.QuickSketch()
bracket.Line(60).Turn(90).Line(10).Turn(90).Line(40)
bracket.Arc(10, -90).Line(30).Turn(90).Line(10).Close()
bracket.Circle(45, 5, 2.5).Circle(5, 35, 2.5)
face = px.Face(bracket.Wires())
face.Plot()

Where to go next

• Quick sketches and constraint sketches: drawing, and dimensions and relations that a solver keeps satisfied.
• Boolean operations, measuring and cleaning up imported drawings.
• Files: DXF, KiCad, SVG, STEP and more.
• OpenCASCADE and netgen/NGSolve: from faces to solids, meshes and simulations.
• Examples: mechanisms, machines, fields and manufacturing.
• Benchmarks: planex2d next to OpenCASCADE and polygon libraries on the same tasks.

License

planex2d is Copyright (C) 2026 Sebastian Hirnschall.

planex2d is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

planex2d is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License, the file LICENSE, for more details. The third-party notices are in THIRD_PARTY_NOTICES.md and on the page License and notices.