games/trek/compkl.c

   1 /*
   2  * Copyright (c) 1980, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)compkl.c 8.1 (Berkeley) 5/31/93
  34  * $FreeBSD: src/games/trek/compkl.c,v 1.4 1999/11/30 03:49:44 billf Exp $
  35  * $DragonFly: src/games/trek/compkl.c,v 1.3 2006/09/07 21:19:44 pavalos Exp $
  36  */
  37
  38 # include       "trek.h"
  39
  40 static void     sortkl(void);
  41
  42 /*
  43 **  compute klingon distances
  44 **
  45 **      The klingon list has the distances for all klingons recomputed
  46 **      and sorted.  The parameter is a Boolean flag which is set if
  47 **      we have just entered a new quadrant.
  48 **
  49 **      This routine is used every time the Enterprise or the Klingons
  50 **      move.
  51 */
  52
  53 void
  54 compkldist(bool f)
  55 {
  56         int             i, dx, dy;
  57         double                  d;
  58         double                  temp;
  59
  60         if (Etc.nkling == 0)
  61                 return;
  62         for (i = 0; i < Etc.nkling; i++)
  63         {
  64                 /* compute distance to the Klingon */
  65                 dx = Ship.sectx - Etc.klingon[i].x;
  66                 dy = Ship.secty - Etc.klingon[i].y;
  67                 d = dx * dx + dy * dy;
  68                 d = sqrt(d);
  69
  70                 /* compute average of new and old distances to Klingon */
  71                 if (!f)
  72                 {
  73                         temp = Etc.klingon[i].dist;
  74                         Etc.klingon[i].avgdist = 0.5 * (temp + d);
  75                 }
  76                 else
  77                 {
  78                         /* new quadrant: average is current */
  79                         Etc.klingon[i].avgdist = d;
  80                 }
  81                 Etc.klingon[i].dist = d;
  82         }
  83
  84         /* leave them sorted */
  85         sortkl();
  86 }
  87
  88
  89 /*
  90 **  sort klingons
  91 **
  92 **      bubble sort on ascending distance
  93 */
  94
  95 static void
  96 sortkl(void)
  97 {
  98         struct kling            t;
  99         int             f, i, m;
 100
 101         m = Etc.nkling - 1;
 102         f = 1;
 103         while (f)
 104         {
 105                 f = 0;
 106                 for (i = 0; i < m; i++)
 107                         if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
 108                         {
 109                                 bmove(&Etc.klingon[i], &t, sizeof t);
 110                                 bmove(&Etc.klingon[i+1], &Etc.klingon[i], sizeof t);
 111                                 bmove(&t, &Etc.klingon[i+1], sizeof t);
 112                                 f = 1;
 113                         }
 114         }
 115 }