games/trek/compkl.c

   1 /*      $NetBSD: compkl.c,v 1.7 2009/05/24 19:18:44 dholland 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. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)compkl.c    8.1 (Berkeley) 5/31/93";
  36 #else
  37 __RCSID("$NetBSD: compkl.c,v 1.7 2009/05/24 19:18:44 dholland Exp $");
  38 #endif
  39 #endif /* not lint */
  40
  41 #include <math.h>
  42 #include "trek.h"
  43
  44 /*
  45 **  compute klingon distances
  46 **
  47 **      The klingon list has the distances for all klingons recomputed
  48 **      and sorted.  The parameter is a Boolean flag which is set if
  49 **      we have just entered a new quadrant.
  50 **
  51 **      This routine is used every time the Enterprise or the Klingons
  52 **      move.
  53 **
  54 **  f -- set if new quadrant
  55 */
  56
  57 static void sortkl(void);
  58
  59 void
  60 compkldist(int f)
  61 {
  62         int             i, dx, dy;
  63         double          d;
  64         double          temp;
  65
  66         if (Etc.nkling == 0)
  67                 return;
  68         for (i = 0; i < Etc.nkling; i++) {
  69                 /* compute distance to the Klingon */
  70                 dx = Ship.sectx - Etc.klingon[i].x;
  71                 dy = Ship.secty - Etc.klingon[i].y;
  72                 d = dx * dx + dy * dy;
  73                 d = sqrt(d);
  74
  75                 /* compute average of new and old distances to Klingon */
  76                 if (!f) {
  77                         temp = Etc.klingon[i].dist;
  78                         Etc.klingon[i].avgdist = 0.5 * (temp + d);
  79                 } else {
  80                         /* new quadrant: average is current */
  81                         Etc.klingon[i].avgdist = d;
  82                 }
  83                 Etc.klingon[i].dist = d;
  84         }
  85
  86         /* leave them sorted */
  87         sortkl();
  88 }
  89
  90
  91 /*
  92 **  sort klingons
  93 **
  94 **      bubble sort on ascending distance
  95 */
  96
  97 static void
  98 sortkl(void)
  99 {
 100         struct kling            t;
 101         int             f, i, m;
 102
 103         m = Etc.nkling - 1;
 104         f = 1;
 105         while (f) {
 106                 f = 0;
 107                 for (i = 0; i < m; i++) {
 108                         if (Etc.klingon[i].dist > Etc.klingon[i+1].dist) {
 109                                 t =  Etc.klingon[i];
 110                                 Etc.klingon[i] = Etc.klingon[i+1];
 111                                 Etc.klingon[i+1] = t;
 112                                 f = 1;
 113                         }
 114                 }
 115         }
 116 }