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compkl.c revision 1.3 
      1 /*	$NetBSD: compkl.c,v 1.3 1995/04/22 10:58:38 cgd 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 #ifndef lint
     37 #if 0
     38 static char sccsid[] = "@(#)compkl.c	8.1 (Berkeley) 5/31/93";
     39 #else
     40 static char rcsid[] = "$NetBSD: compkl.c,v 1.3 1995/04/22 10:58:38 cgd Exp $";
     41 #endif
     42 #endif /* not lint */
     43 
     44 # include	"trek.h"
     45 
     46 /*
     47 **  compute klingon distances
     48 **
     49 **	The klingon list has the distances for all klingons recomputed
     50 **	and sorted.  The parameter is a Boolean flag which is set if
     51 **	we have just entered a new quadrant.
     52 **
     53 **	This routine is used every time the Enterprise or the Klingons
     54 **	move.
     55 */
     56 
     57 compkldist(f)
     58 int	f;		/* set if new quadrant */
     59 {
     60 	register int		i, dx, dy;
     61 	double			d;
     62 	double			temp;
     63 
     64 	if (Etc.nkling == 0)
     65 		return;
     66 	for (i = 0; i < Etc.nkling; i++)
     67 	{
     68 		/* compute distance to the Klingon */
     69 		dx = Ship.sectx - Etc.klingon[i].x;
     70 		dy = Ship.secty - Etc.klingon[i].y;
     71 		d = dx * dx + dy * dy;
     72 		d = sqrt(d);
     73 
     74 		/* compute average of new and old distances to Klingon */
     75 		if (!f)
     76 		{
     77 			temp = Etc.klingon[i].dist;
     78 			Etc.klingon[i].avgdist = 0.5 * (temp + d);
     79 		}
     80 		else
     81 		{
     82 			/* new quadrant: average is current */
     83 			Etc.klingon[i].avgdist = d;
     84 		}
     85 		Etc.klingon[i].dist = d;
     86 	}
     87 
     88 	/* leave them sorted */
     89 	sortkl();
     90 }
     91 
     92 
     93 /*
     94 **  sort klingons
     95 **
     96 **	bubble sort on ascending distance
     97 */
     98 
     99 sortkl()
    100 {
    101 	struct kling		t;
    102 	register int		f, i, m;
    103 
    104 	m = Etc.nkling - 1;
    105 	f = 1;
    106 	while (f)
    107 	{
    108 		f = 0;
    109 		for (i = 0; i < m; i++)
    110 			if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
    111 			{
    112 				bmove(&Etc.klingon[i], &t, sizeof t);
    113 				bmove(&Etc.klingon[i+1], &Etc.klingon[i], sizeof t);
    114 				bmove(&t, &Etc.klingon[i+1], sizeof t);
    115 				f = 1;
    116 			}
    117 	}
    118 }
    119