/* The mesh structure is similar in spirit, notation, and operations
 * to the "quad-edge" structure (see L. Guibas and J. Stolfi, Primitives
 * for the manipulation of general subdivisions and the computation of
 * Voronoi diagrams, ACM Transactions on Graphics, 4(2):74-123, April 1985).
 * For a simplified description, see the course notes for CS348a,
 * "Mathematical Foundations of Computer Graphics", available at the
 * Stanford bookstore (and taught during the fall quarter).
 * The implementation also borrows a tiny subset of the graph-based approach
 * use in Mantyla's Geometric Work Bench (see M. Mantyla, An Introduction
 * to Sold Modeling, Computer Science Press, Rockville, Maryland, 1988).
 *
 * The fundamental data structure is the "half-edge".  Two half-edges
 * go together to make an edge, but they point in opposite directions.
 * Each half-edge has a pointer to its mate (the "symmetric" half-edge Sym),
 * its origin vertex (Org), the face on its left side (Lface), and the
 * adjacent half-edges in the CCW direction around the origin vertex
 * (Onext) and around the left face (Lnext).  There is also a "next"
 * pointer for the global edge list (see below).
 *
 * The notation used for mesh navigation:
 *  Sym   = the mate of a half-edge (same edge, but opposite direction)
 *  Onext = edge CCW around origin vertex (keep same origin)
 *  Dnext = edge CCW around destination vertex (keep same dest)
 *  Lnext = edge CCW around left face (dest becomes new origin)
 *  Rnext = edge CCW around right face (origin becomes new dest)
 *
 * "prev" means to substitute CW for CCW in the definitions above.
 *
 * The mesh keeps global lists of all vertices, faces, and edges,
 * stored as doubly-linked circular lists with a dummy header node.
 * The mesh stores pointers to these dummy headers (vHead, fHead, eHead).
 *
 * The circular edge list is special; since half-edges always occur
 * in pairs (e and e->Sym), each half-edge stores a pointer in only
 * one direction.  Starting at eHead and following the e->next pointers
 * will visit each *edge* once (ie. e or e->Sym, but not both).
 * e->Sym stores a pointer in the opposite direction, thus it is
 * always true that e->Sym->next->Sym->next == e.
 *
 * Each vertex has a pointer to next and previous vertices in the
 * circular list, and a pointer to a half-edge with this vertex as
 * the origin (NULL if this is the dummy header).  There is also a
 * field "data" for client data.
 *
 * Each face has a pointer to the next and previous faces in the
 * circular list, and a pointer to a half-edge with this face as
 * the left face (NULL if this is the dummy header).  There is also
 * a field "data" for client data.
 *
 * Note that what we call a "face" is really a loop; faces may consist
 * of more than one loop (ie. not simply connected), but there is no
 * record of this in the data structure.  The mesh may consist of
 * several disconnected regions, so it may not be possible to visit
 * the entire mesh by starting at a half-edge and traversing the edge
 * structure.
 *
 * The mesh does NOT support isolated vertices; a vertex is deleted along
 * with its last edge.  Similarly when two faces are merged, one of the
 * faces is deleted (see tessMeshDelete below).  For mesh operations,
 * all face (loop) and vertex pointers must not be NULL.  However, once
 * mesh manipulation is finished, TESSmeshZapFace can be used to delete
 * faces of the mesh, one at a time.  All external faces can be "zapped"
 * before the mesh is returned to the client; then a NULL face indicates
 * a region which is not part of the output polygon.
 */

 export * from "./ActiveRegion";
 export * from "./TESShalfEdge";
 export * from "./TESSface";
 export * from "./TESSvertex";
 export * from "./TESSmesh";