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