trek/compkl.c

   1 /*
   2  * Copyright (c) 1980 Regents of the University of California.
   3  * 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
  34 #ifndef lint
  35 /*static char sccsid[] = "from: @(#)compkl.c    5.4 (Berkeley) 6/1/90";*/
  36 static char rcsid[] = "$Id: compkl.c,v 1.2 1993/08/01 18:50:47 mycroft Exp $";
  37 #endif /* not lint */
  38
  39 # include       "trek.h"
  40
  41 /*
  42 **  compute klingon distances
  43 **
  44 **      The klingon list has the distances for all klingons recomputed
  45 **      and sorted.  The parameter is a Boolean flag which is set if
  46 **      we have just entered a new quadrant.
  47 **
  48 **      This routine is used every time the Enterprise or the Klingons
  49 **      move.
  50 */
  51
  52 compkldist(f)
  53 int     f;              /* set if new quadrant */
  54 {
  55         register int            i, dx, dy;
  56         double                  d;
  57         double                  temp;
  58
  59         if (Etc.nkling == 0)
  60                 return;
  61         for (i = 0; i < Etc.nkling; i++)
  62         {
  63                 /* compute distance to the Klingon */
  64                 dx = Ship.sectx - Etc.klingon[i].x;
  65                 dy = Ship.secty - Etc.klingon[i].y;
  66                 d = dx * dx + dy * dy;
  67                 d = sqrt(d);
  68
  69                 /* compute average of new and old distances to Klingon */
  70                 if (!f)
  71                 {
  72                         temp = Etc.klingon[i].dist;
  73                         Etc.klingon[i].avgdist = 0.5 * (temp + d);
  74                 }
  75                 else
  76                 {
  77                         /* new quadrant: average is current */
  78                         Etc.klingon[i].avgdist = d;
  79                 }
  80                 Etc.klingon[i].dist = d;
  81         }
  82
  83         /* leave them sorted */
  84         sortkl();
  85 }
  86
  87
  88 /*
  89 **  sort klingons
  90 **
  91 **      bubble sort on ascending distance
  92 */
  93
  94 sortkl()
  95 {
  96         struct kling            t;
  97         register int            f, i, m;
  98
  99         m = Etc.nkling - 1;
 100         f = 1;
 101         while (f)
 102         {
 103                 f = 0;
 104                 for (i = 0; i < m; i++)
 105                         if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
 106                         {
 107                                 bmove(&Etc.klingon[i], &t, sizeof t);
 108                                 bmove(&Etc.klingon[i+1], &Etc.klingon[i], sizeof t);
 109                                 bmove(&t, &Etc.klingon[i+1], sizeof t);
 110                                 f = 1;
 111                         }
 112         }
 113 }