Home | History | Annotate | Line # | Download | only in trek
compkl.c revision 1.4 
      1 /*	$NetBSD: compkl.c,v 1.4 1997/10/12 21:24:33 christos 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 #if 0
     39 static char sccsid[] = "@(#)compkl.c	8.1 (Berkeley) 5/31/93";
     40 #else
     41 __RCSID("$NetBSD: compkl.c,v 1.4 1997/10/12 21:24:33 christos Exp $");
     42 #endif
     43 #endif /* not lint */
     44 
     45 #include <math.h>
     46 #include "trek.h"
     47 
     48 /*
     49 **  compute klingon distances
     50 **
     51 **	The klingon list has the distances for all klingons recomputed
     52 **	and sorted.  The parameter is a Boolean flag which is set if
     53 **	we have just entered a new quadrant.
     54 **
     55 **	This routine is used every time the Enterprise or the Klingons
     56 **	move.
     57 */
     58 
     59 static void sortkl __P((void));
     60 
     61 void
     62 compkldist(f)
     63 int	f;		/* set if new quadrant */
     64 {
     65 	int		i, dx, dy;
     66 	double		d;
     67 	double		temp;
     68 
     69 	if (Etc.nkling == 0)
     70 		return;
     71 	for (i = 0; i < Etc.nkling; i++)
     72 	{
     73 		/* compute distance to the Klingon */
     74 		dx = Ship.sectx - Etc.klingon[i].x;
     75 		dy = Ship.secty - Etc.klingon[i].y;
     76 		d = dx * dx + dy * dy;
     77 		d = sqrt(d);
     78 
     79 		/* compute average of new and old distances to Klingon */
     80 		if (!f)
     81 		{
     82 			temp = Etc.klingon[i].dist;
     83 			Etc.klingon[i].avgdist = 0.5 * (temp + d);
     84 		}
     85 		else
     86 		{
     87 			/* new quadrant: average is current */
     88 			Etc.klingon[i].avgdist = d;
     89 		}
     90 		Etc.klingon[i].dist = d;
     91 	}
     92 
     93 	/* leave them sorted */
     94 	sortkl();
     95 }
     96 
     97 
     98 /*
     99 **  sort klingons
    100 **
    101 **	bubble sort on ascending distance
    102 */
    103 
    104 static void
    105 sortkl()
    106 {
    107 	struct kling		t;
    108 	int		f, i, m;
    109 
    110 	m = Etc.nkling - 1;
    111 	f = 1;
    112 	while (f)
    113 	{
    114 		f = 0;
    115 		for (i = 0; i < m; i++)
    116 			if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
    117 			{
    118 				t =  Etc.klingon[i];
    119 				Etc.klingon[i] = Etc.klingon[i+1];
    120 				Etc.klingon[i+1] = t;
    121 				f = 1;
    122 			}
    123 	}
    124 }
    125