1/*	$NetBSD: compkl.c,v 1.7 2009/05/24 19:18:44 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
35static char sccsid[] = "@(#)compkl.c	8.1 (Berkeley) 5/31/93";
36#else
37__RCSID("$NetBSD: compkl.c,v 1.7 2009/05/24 19:18:44 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
57static void sortkl(void);
58
59void
60compkldist(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
97static void
98sortkl(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