games/trek/compkl.c

   1 /*      @(#)compkl.c    8.1 (Berkeley) 5/31/93                          */
   2 /*      $NetBSD: compkl.c,v 1.8 2009/05/24 21:44:56 dholland Exp $      */
   3
   4 /*
   5  * Copyright (c) 1980, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <math.h>
  34 #include "trek.h"
  35
  36 /*
  37 **  compute klingon distances
  38 **
  39 **      The klingon list has the distances for all klingons recomputed
  40 **      and sorted.  The parameter is a Boolean flag which is set if
  41 **      we have just entered a new quadrant.
  42 **
  43 **      This routine is used every time the Enterprise or the Klingons
  44 **      move.
  45 **
  46 **  f -- set if new quadrant
  47 */
  48
  49 static void sortkl(void);
  50
  51 void
  52 compkldist(int f)
  53 {
  54         int             i, dx, dy;
  55         double          d;
  56         double          temp;
  57
  58         if (Etc.nkling == 0)
  59                 return;
  60         for (i = 0; i < Etc.nkling; i++) {
  61                 /* compute distance to the Klingon */
  62                 dx = Ship.sectx - Etc.klingon[i].x;
  63                 dy = Ship.secty - Etc.klingon[i].y;
  64                 d = dx * dx + dy * dy;
  65                 d = sqrt(d);
  66
  67                 /* compute average of new and old distances to Klingon */
  68                 if (!f) {
  69                         temp = Etc.klingon[i].dist;
  70                         Etc.klingon[i].avgdist = 0.5 * (temp + d);
  71                 } else {
  72                         /* new quadrant: average is current */
  73                         Etc.klingon[i].avgdist = d;
  74                 }
  75                 Etc.klingon[i].dist = d;
  76         }
  77
  78         /* leave them sorted */
  79         sortkl();
  80 }
  81
  82
  83 /*
  84 **  sort klingons
  85 **
  86 **      bubble sort on ascending distance
  87 */
  88
  89 static void
  90 sortkl(void)
  91 {
  92         struct kling            t;
  93         int             f, i, m;
  94
  95         m = Etc.nkling - 1;
  96         f = 1;
  97         while (f) {
  98                 f = 0;
  99                 for (i = 0; i < m; i++) {
 100                         if (Etc.klingon[i].dist > Etc.klingon[i+1].dist) {
 101                                 t =  Etc.klingon[i];
 102                                 Etc.klingon[i] = Etc.klingon[i+1];
 103                                 Etc.klingon[i+1] = t;
 104                                 f = 1;
 105                         }
 106                 }
 107         }
 108 }