planegcs

Python bindings for FreeCAD's PlaneGCS 2D geometric constraint solver.

This project extracts the constraint solver system from FreeCAD's Sketcher component, changes the headers so that it can be used outside FreeCAD, and adds some thin C++ and Python wrappers so it can be used as a Python library. As per the FreeCAD licence requirements, the result is licenced under the LPGL 2.1 or later.

Installation

pip install planegcs

or:

uv add planegcs

If wheels aren't available, you'll need C++ tools and some development headers:

• eigen3
• boost

Quick Start

from planegcs import Sketch, SolveStatus

s = Sketch()

# Create three points for a triangle
p1 = s.add_fixed_point(0, 0)
p2 = s.add_point(5, 0)
p3 = s.add_point(2.5, 4)

# Create lines
l1 = s.add_line(p1, p2)
l2 = s.add_line(p2, p3)
l3 = s.add_line(p3, p1)

# Make it equilateral
s.equal_length(l1, l2)
s.equal_length(l2, l3)

# Make base horizontal
s.horizontal(l1)

# Fix the side length to 5
s.set_p2p_distance(p1, p2, 5.0)

# Solve
status = s.solve()
assert status == SolveStatus.Success

# Read results
print(s.get_point(p1))  # (0.0, 0.0)
print(s.get_point(p2))  # (5.0, 0.0)
print(s.get_point(p3))  # (~2.5, ~4.33)

Docs

Full documentation at readthedocs, and in the docs/ folder (requires Sphinx to build).

License

LGPL-2.1-or-later (same as the FreeCAD source code it wraps).