trek/compkl.c

   1 /*      $NetBSD: compkl.c,v 1.4 1997/10/12 21:24:33 christos Exp $      */
   2
   3 /*
   4  * Copyright (c) 1980, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 #ifndef lint
  38 #if 0
  39 static char sccsid[] = "@(#)compkl.c    8.1 (Berkeley) 5/31/93";
  40 #else
  41 __RCSID("$NetBSD: compkl.c,v 1.4 1997/10/12 21:24:33 christos Exp $");
  42 #endif
  43 #endif /* not lint */
  44
  45 #include <math.h>
  46 #include "trek.h"
  47
  48 /*
  49 **  compute klingon distances
  50 **
  51 **      The klingon list has the distances for all klingons recomputed
  52 **      and sorted.  The parameter is a Boolean flag which is set if
  53 **      we have just entered a new quadrant.
  54 **
  55 **      This routine is used every time the Enterprise or the Klingons
  56 **      move.
  57 */
  58
  59 static void sortkl __P((void));
  60
  61 void
  62 compkldist(f)
  63 int     f;              /* set if new quadrant */
  64 {
  65         int             i, dx, dy;
  66         double          d;
  67         double          temp;
  68
  69         if (Etc.nkling == 0)
  70                 return;
  71         for (i = 0; i < Etc.nkling; i++)
  72         {
  73                 /* compute distance to the Klingon */
  74                 dx = Ship.sectx - Etc.klingon[i].x;
  75                 dy = Ship.secty - Etc.klingon[i].y;
  76                 d = dx * dx + dy * dy;
  77                 d = sqrt(d);
  78
  79                 /* compute average of new and old distances to Klingon */
  80                 if (!f)
  81                 {
  82                         temp = Etc.klingon[i].dist;
  83                         Etc.klingon[i].avgdist = 0.5 * (temp + d);
  84                 }
  85                 else
  86                 {
  87                         /* new quadrant: average is current */
  88                         Etc.klingon[i].avgdist = d;
  89                 }
  90                 Etc.klingon[i].dist = d;
  91         }
  92
  93         /* leave them sorted */
  94         sortkl();
  95 }
  96
  97
  98 /*
  99 **  sort klingons
 100 **
 101 **      bubble sort on ascending distance
 102 */
 103
 104 static void
 105 sortkl()
 106 {
 107         struct kling            t;
 108         int             f, i, m;
 109
 110         m = Etc.nkling - 1;
 111         f = 1;
 112         while (f)
 113         {
 114                 f = 0;
 115                 for (i = 0; i < m; i++)
 116                         if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
 117                         {
 118                                 t =  Etc.klingon[i];
 119                                 Etc.klingon[i] = Etc.klingon[i+1];
 120                                 Etc.klingon[i+1] = t;
 121                                 f = 1;
 122                         }
 123         }
 124 }