lib/neatogen/voronoi.c

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/* $Id$ $Revision$ */
/* vim:set shiftwidth=4 ts=8: */

/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: See CVS logs. Details at http://www.graphviz.org/
 *************************************************************************/

#include "mem.h"
#include "geometry.h"
#include "edges.h"
#include "hedges.h"
#include "heap.h"
#include "voronoi.h"


void voronoi(int triangulate, Site * (*nextsite) (void))
{
    Site *newsite, *bot, *top, *temp, *p;
    Site *v;
    Point newintstar;
    char pm;
    Halfedge *lbnd, *rbnd, *llbnd, *rrbnd, *bisector;
    Edge *e;

    edgeinit();
    siteinit();
    PQinitialize();
    bottomsite = (*nextsite) ();
#ifdef STANDALONE
    out_site(bottomsite);
#endif
    ELinitialize();

    newsite = (*nextsite) ();
    while (1) {
        if (!PQempty())
            newintstar = PQ_min();

        if (newsite != (struct Site *) NULL && (PQempty()
                                                || newsite->coord.y <
                                                newintstar.y
                                                || (newsite->coord.y ==
                                                    newintstar.y
                                                    && newsite->coord.x <
                                                    newintstar.x))) {
            /* new site is smallest */
#ifdef STANDALONE
            out_site(newsite);
#endif
            lbnd = ELleftbnd(&(newsite->coord));
            rbnd = ELright(lbnd);
            bot = rightreg(lbnd);
            e = bisect(bot, newsite);
            bisector = HEcreate(e, le);
            ELinsert(lbnd, bisector);
            if ((p = hintersect(lbnd, bisector)) != (struct Site *) NULL) {
                PQdelete(lbnd);
                PQinsert(lbnd, p, dist(p, newsite));
            }
            lbnd = bisector;
            bisector = HEcreate(e, re);
            ELinsert(lbnd, bisector);
            if ((p = hintersect(bisector, rbnd)) != (struct Site *) NULL)
                PQinsert(bisector, p, dist(p, newsite));
            newsite = (*nextsite) ();
        } else if (!PQempty()) {
            /* intersection is smallest */
            lbnd = PQextractmin();
            llbnd = ELleft(lbnd);
            rbnd = ELright(lbnd);
            rrbnd = ELright(rbnd);
            bot = leftreg(lbnd);
            top = rightreg(rbnd);
#ifdef STANDALONE
            out_triple(bot, top, rightreg(lbnd));
#endif
            v = lbnd->vertex;
            makevertex(v);
            endpoint(lbnd->ELedge, lbnd->ELpm, v);
            endpoint(rbnd->ELedge, rbnd->ELpm, v);
            ELdelete(lbnd);
            PQdelete(rbnd);
            ELdelete(rbnd);
            pm = le;
            if (bot->coord.y > top->coord.y) {
                temp = bot;
                bot = top;
                top = temp;
                pm = re;
            }
            e = bisect(bot, top);
            bisector = HEcreate(e, pm);
            ELinsert(llbnd, bisector);
            endpoint(e, re - pm, v);
            deref(v);
            if ((p = hintersect(llbnd, bisector)) != (struct Site *) NULL) {
                PQdelete(llbnd);
                PQinsert(llbnd, p, dist(p, bot));
            }
            if ((p = hintersect(bisector, rrbnd)) != (struct Site *) NULL) {
                PQinsert(bisector, p, dist(p, bot));
            }
        } else
            break;
    }

    for (lbnd = ELright(ELleftend); lbnd != ELrightend;
         lbnd = ELright(lbnd)) {
        e = lbnd->ELedge;
        clip_line(e);
#ifdef STANDALONE
        out_ep(e);
#endif
    }
}