1 /* $OpenBSD: compkl.c,v 1.8 2016/01/07 14:37:51 mestre Exp $ */
2 /* $NetBSD: compkl.c,v 1.3 1995/04/22 10:58:38 cgd Exp $ */
3
4 /*
5 * Copyright (c) 1980, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <math.h>
34
35 #include "trek.h"
36
37 /*
38 ** compute klingon distances
39 **
40 ** The klingon list has the distances for all klingons recomputed
41 ** and sorted. The parameter is a Boolean flag which is set if
42 ** we have just entered a new quadrant.
43 **
44 ** This routine is used every time the Enterprise or the Klingons
45 ** move.
46 */
47
48 static void sortkl(void);
49
50 /* argument is set if new quadrant */
51 void
compkldist(int f)52 compkldist(int f)
53 {
54 int i, dx, dy;
55 double d;
56 double temp;
57
58 if (Etc.nkling == 0)
59 return;
60 for (i = 0; i < Etc.nkling; i++)
61 {
62 /* compute distance to the Klingon */
63 dx = Ship.sectx - Etc.klingon[i].x;
64 dy = Ship.secty - Etc.klingon[i].y;
65 d = dx * dx + dy * dy;
66 d = sqrt(d);
67
68 /* compute average of new and old distances to Klingon */
69 if (!f)
70 {
71 temp = Etc.klingon[i].dist;
72 Etc.klingon[i].avgdist = 0.5 * (temp + d);
73 }
74 else
75 {
76 /* new quadrant: average is current */
77 Etc.klingon[i].avgdist = d;
78 }
79 Etc.klingon[i].dist = d;
80 }
81
82 /* leave them sorted */
83 sortkl();
84 }
85
86
87 /*
88 ** sort klingons
89 **
90 ** bubble sort on ascending distance
91 */
92
93 static void
sortkl(void)94 sortkl(void)
95 {
96 struct kling t;
97 int f, i, m;
98
99 m = Etc.nkling - 1;
100 f = 1;
101 while (f)
102 {
103 f = 0;
104 for (i = 0; i < m; i++)
105 if (Etc.klingon[i].dist > Etc.klingon[i+1].dist)
106 {
107 t = Etc.klingon[i];
108 Etc.klingon[i] = Etc.klingon[i + 1];
109 Etc.klingon[i + 1] = t;
110 f = 1;
111 }
112 }
113 }
114