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
compkldist(int f)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
sortkl(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