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      1 /*	$NetBSD: compkl.c,v 1.8 2009/05/24 21:44:56 dholland 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 1.8 2009/05/24 21:44:56 dholland 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 **  f -- set if new quadrant
     55 */
     56 
     57 static void sortkl(void);
     58 
     59 void
     60 compkldist(int f)
     61 {
     62 	int		i, dx, dy;
     63 	double		d;
     64 	double		temp;
     65 
     66 	if (Etc.nkling == 0)
     67 		return;
     68 	for (i = 0; i < Etc.nkling; i++) {
     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 			temp = Etc.klingon[i].dist;
     78 			Etc.klingon[i].avgdist = 0.5 * (temp + d);
     79 		} else {
     80 			/* new quadrant: average is current */
     81 			Etc.klingon[i].avgdist = d;
     82 		}
     83 		Etc.klingon[i].dist = d;
     84 	}
     85 
     86 	/* leave them sorted */
     87 	sortkl();
     88 }
     89 
     90 
     91 /*
     92 **  sort klingons
     93 **
     94 **	bubble sort on ascending distance
     95 */
     96 
     97 static void
     98 sortkl(void)
     99 {
    100 	struct kling		t;
    101 	int		f, i, m;
    102 
    103 	m = Etc.nkling - 1;
    104 	f = 1;
    105 	while (f) {
    106 		f = 0;
    107 		for (i = 0; i < m; i++) {
    108 			if (Etc.klingon[i].dist > Etc.klingon[i+1].dist) {
    109 				t =  Etc.klingon[i];
    110 				Etc.klingon[i] = Etc.klingon[i+1];
    111 				Etc.klingon[i+1] = t;
    112 				f = 1;
    113 			}
    114 		}
    115 	}
    116 }
    117