/*      @(#)compkl.c    8.1 (Berkeley) 5/31/93                          */
/*      $NetBSD: compkl.c,v 1.8 2009/05/24 21:44:56 dholland Exp $      */

/*
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <math.h>
#include "trek.h"

/*
**  compute klingon distances
**
**      The klingon list has the distances for all klingons recomputed
**      and sorted.  The parameter is a Boolean flag which is set if
**      we have just entered a new quadrant.
**
**      This routine is used every time the Enterprise or the Klingons
**      move.
**
**  f -- set if new quadrant
*/

static void sortkl(void);

void
compkldist(int f)
{
        int             i, dx, dy;
        double          d;
        double          temp;

        if (Etc.nkling == 0)
                return;
        for (i = 0; i < Etc.nkling; i++) {
                /* compute distance to the Klingon */
                dx = Ship.sectx - Etc.klingon[i].x;
                dy = Ship.secty - Etc.klingon[i].y;
                d = dx * dx + dy * dy;
                d = sqrt(d);

                /* compute average of new and old distances to Klingon */
                if (!f) {
                        temp = Etc.klingon[i].dist;
                        Etc.klingon[i].avgdist = 0.5 * (temp + d);
                } else {
                        /* new quadrant: average is current */
                        Etc.klingon[i].avgdist = d;
                }
                Etc.klingon[i].dist = d;
        }

        /* leave them sorted */
        sortkl();
}


/*
**  sort klingons
**
**      bubble sort on ascending distance
*/

static void
sortkl(void)
{
        struct kling            t;
        int             f, i, m;

        m = Etc.nkling - 1;
        f = 1;
        while (f) {
                f = 0;
                for (i = 0; i < m; i++) {
                        if (Etc.klingon[i].dist > Etc.klingon[i+1].dist) {
                                t =  Etc.klingon[i];
                                Etc.klingon[i] = Etc.klingon[i+1];
                                Etc.klingon[i+1] = t;
                                f = 1;
                        }
                }
        }
}