geompack, a C code which carries out certain geometric computations, including the convex hull, the Delaunay triangulation and the Voronoi diagram of a set of points in the plane, by Barry Joe.
The information on this web page is distributed under the MIT license.
geompack is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave version.
geometry, a C library which carries out geometric calculations in 2, 3 and N dimensional space.
Original Fortran77 version by Barry Joe; This version by John Burkardt.