pyclipper

What it is and what it does

Pyclipper is a Cython wrapper around Angus Johnson's Clipper library (version 6.4.2), a C++ polygon clipping and offsetting engine. It exposes the core clipping operations—intersection, union, difference, and exclusive-or—as well as polygon offsetting, using Vatti's clipping algorithm for numerical robustness. The library works with integer coordinates internally to avoid floating-point precision issues; helper functions scale_to_clipper() and scale_from_clipper() are provided to convert between floating-point and integer representations.

The package is designed for developers working with computational geometry, graphics, or CAD-like applications. It has no runtime dependencies beyond Python itself. The API closely mirrors the original C++ library's naming conventions, with classes Pyclipper and PyclipperOffset replacing the C++ Clipper and ClipperOffset. Since version 1.0.0, automatic scaling via SCALING_FACTOR was removed to preserve the original library's numerical robustness, which is a breaking change from earlier versions.

Use it for:

• Compute intersections, unions, or differences of polygon regions in graphics or GIS applications.
• Offset polygon boundaries inward or outward by a fixed distance for buffer operations.
• Perform boolean operations on closed polygons in CAD or design software.
• Combine multiple polygon paths with clipping rules (even-odd or non-zero winding) in computational geometry.
• Scale and clip line segments or polygons while maintaining numerical precision in scientific applications.

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

Pyclipper performs polygon clipping operations (intersection, union, difference, exclusive-or) and polygon offsetting using a Cython wrapper around the C++ Clipper library version 6.4.2.

Yes, if you need robust polygon clipping or offsetting. The package is stable, has no known vulnerabilities, supports current Python versions (3.10–3.14), and is widely downloaded (11.7M monthly). The aging maintenance status (256 days since release) is a minor concern but not a blocker; the repository is active and the underlying algorithm is mature. Install friction is moderate due to compilation, but prebuilt wheels are available for common platforms. Breaking changes in version 1.0.0 (SCALING_FACTOR removal) may affect legacy code, so review migration notes if upgrading from 0.9.3b0.

Install

pyclipper on PyPI

pip install pyclipper

uv add pyclipper

poetry add pyclipper

Installing pyclipper

Before you install

Medium install friction due to compiled C++ extension; however, prebuilt wheels are available for Python 3.10–3.14 across Windows, macOS, and Linux platforms. Package is aging (256 days since last release) but repository remains active with 261 stars and no archived status.

License in practice

MIT license (permissive); the underlying Clipper library is Boost Software License (freeware for open source and commercial use). No licensing restrictions on your use of pyclipper.

Quickstart

pip install pyclipper

import pyclipper

pc = pyclipper.Pyclipper()
pc.AddPath(((190, 210), (240, 210), (240, 130), (190, 130)), pyclipper.PT_CLIP, True)
pc.AddPaths((((180, 200), (260, 200), (260, 150), (180, 150)),), pyclipper.PT_SUBJECT, True)
solution = pc.Execute(pyclipper.CT_INTERSECTION, pyclipper.PFT_EVENODD, pyclipper.PFT_EVENODD)

Requires Python 3.10 or later; compiled extension may require build tools if installing from source rather than a prebuilt wheel.

Verify before relying

• Whether the package is actively maintained going forward (last release 256 days ago, status marked 'aging').
• Performance characteristics and scalability limits for large polygon datasets or complex clipping operations.
• Availability of documentation beyond the README and GitHub wiki.

Package facts

Evidence: pyclipper-1.4.0-cp310-cp310-macosx_10_9_universal2.whl; pyclipper-1.4.0-cp310-cp310-macosx_10_9_x86_64.whl; pyclipper-1.4.0-cp310-cp310-manylinux2014_x86_64.manylinux_2_17_x86_64.whl; pyclipper-1.4.0-cp310-cp310-manylinux_2_24_aarch64.manylinux_2_28_aarch64.whl; pyclipper-1.4.0-cp310-cp310-win32.whl; pyclipper-1.4.0-cp310-cp310-win_amd64.whl; pyclipper-1.4.0-cp311-cp311-macosx_10_9_universal2.whl; pyclipper-1.4.0-cp311-cp311-macosx_10_9_x86_64.whl; pyclipper-1.4.0-cp311-cp311-manylinux2014_x86_64.manylinux_2_17_x86_64.whl; pyclipper-1.4.0-cp311-cp311-manylinux_2_24_aarch64.manylinux_2_28_aarch64.whl; pyclipper-1.4.0-cp311-cp311-win32.whl; pyclipper-1.4.0-cp311-cp311-win_amd64.whl; pyclipper-1.4.0-cp312-cp312-macosx_10_13_universal2.whl; pyclipper-1.4.0-cp312-cp312-macosx_10_13_x86_64.whl; pyclipper-1.4.0-cp312-cp312-manylinux2014_x86_64.manylinux_2_17_x86_64.whl; pyclipper-1.4.0-cp312-cp312-manylinux_2_24_aarch64.manylinux_2_28_aarch64.whl; pyclipper-1.4.0-cp312-cp312-win32.whl; pyclipper-1.4.0-cp312-cp312-win_amd64.whl; pyclipper-1.4.0-cp313-cp313-macosx_10_13_universal2.whl; pyclipper-1.4.0-cp313-cp313-macosx_10_13_x86_64.whl

Keywords: polygon clipping, polygon intersection, polygon union, polygon offsetting, polygon boolean, polygon, clipping, clipper, vatti

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