OpenCAMLib ("ocl") is a GPL licensed C++ library with Python bindings for creating toolpaths for cnc-machines.
Cutter projection algorithms are used to project milling cutters axially ("drop-cutter") or radially ("push-cutter") in contact with a polygonal surface.
A Voronoi diagram algorithm is being developed for generation of 2D offsets.
A Cutting simulation engine is developed to simulate milling and turning. It has now been spun off into its own project at https://github.com/aewallin/cutsim