Author: Yotam Gingold <yotam (strudel) yotamgingold.com>
License: Public Domain.  (I, Yotam Gingold, the author, release this code into the public domain.)
GitHub: https://github.com/yig/halfedge

trimesh.h trimesh_t:
    A C++ half-edge data structure for a triangle mesh with no external dependencies whatsoever that
        - handles boundaries (the first outgoing halfedge at a vertex is always a boundary halfedge)
          (and the last outgoing halfedge is always the opposite of a boundary halfedge))
        - stores topology only; it does not "own" or store your vertices;
          rather it looks only at faces and only while building the half-edges
          (make sure to re-create the half-edges anytime the faces change!)

example.cpp:
    A very simple file to show usage of trimesh_t.
    Compile it with the one-liner at the top.

Usage:
    std::vector< trimesh::triangle_t > triangles;
    
    // ... fill triangles ...
    
    std::vector< trimesh::edge_t > edges;
    trimesh::unordered_edges_from_triangles( triangles.size(), &triangles[0], edges );
    
    trimesh::trimesh_t mesh;
    mesh.build( num_vertices, triangles.size(), &triangles[0], edges.size(), &edges[0] );
    
    // Use 'mesh' to walk the connectivity.

Version History:
    - 2012-01-12:
        initial release