Ken ClarkSon's convex hulls, Delaunay triangulations, alpha shapes calculator in C
GDSII viewer + Algorithms for 2d polygon boolean operations, C++ source code
Jeff Erickson's links to freely available implementations of geometric algorithms and software.
By Martin Held. Copes with polygons with holes and degeneracies/self-intersections; based on repeatedly clipping ears. Source code on request.
Mesh generation in 2D and 3D on Unix and NT, and related software by Steven Vavasis.
J-D. Boissonnat et al.'s code for Delaunay meshing in 2 and 3 dimensions in C++.
C code for orientation and incircle tests using adaptive-precision floating-point arithmetic
Summary of major CG problems and implementations of their solutions
Two Java applets for editing polygons and point sets for input to computational geometry software.
Gmsh is a three-dimensional finite element mesh generator, primarily Delaunay, with built-in pre- and post-processing facilities. Gmsh is freely available for Windows and most UNIX platforms.