1: /*      $NetBSD: compkl.c,v 1.6 2004/01/27 20:30:30 jsm 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 1.6 2004/01/27 20:30:30 jsm 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: 
   55: static void sortkl(void);
   56: 
   57: void
   58: compkldist(f)
   59: int     f;          /* set if new quadrant */
   60: {
   61:         int            i, dx, dy;
   62:         double         d;
   63:         double         temp;
   64: 
   65:         if (Etc.nkling == 0)
   66:                 return;
   67:         for (i = 0; i < Etc.nkling; i++)
   68:         {
   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:                 {
   78:                         temp = Etc.klingon[i].dist;
   79:                         Etc.klingon[i].avgdist = 0.5 * (temp + d);
   80:                 }
   81:                 else
   82:                 {
   83:                         /* new quadrant: average is current */
   84:                         Etc.klingon[i].avgdist = d;
   85:                 }
   86:                 Etc.klingon[i].dist = d;
   87:         }
   88: 
   89:         /* leave them sorted */
   90:         sortkl();
   91: }
   92: 
   93: 
   94: /*
   95: **  sort klingons
   96: **
   97: **      bubble sort on ascending distance
   98: */
   99: 
  100: static void
  101: sortkl()
  102: {
  103:         struct kling           t;
  104:         int            f, i, m;
  105: 
  106:         m = Etc.nkling - 1;
  107:         f = 1;
  108:         while (f)
  109:         {
  110:                 f = 0;
  111:                 for (i = 0; i < m; i++)
  112:                         if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
  113:                         {
  114:                                 t =  Etc.klingon[i];
  115:                                 Etc.klingon[i] = Etc.klingon[i+1];
  116:                                 Etc.klingon[i+1] = t;
  117:                                 f = 1;
  118:                         }
  119:         }
  120: }