1 /* $Id: math.c,v 5.2 2003/09/16 21:00:16 bertg Exp $
2 *
3 * XPilot, a multiplayer gravity war game. Copyright (C) 1991-2001 by
4 *
5 * Bj�rn Stabell <bjoern@xpilot.org>
6 * Ken Ronny Schouten <ken@xpilot.org>
7 * Bert Gijsbers <bert@xpilot.org>
8 * Dick Balaska <dick@xpilot.org>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 */
24
25 #include <stdlib.h>
26 #include <stdio.h>
27 #include <string.h>
28 #include <errno.h>
29 #include <math.h>
30
31 #include "version.h"
32 #include "config.h"
33 #include "const.h"
34 #include "error.h"
35 #include "commonproto.h"
36
37
38 char math_version[] = VERSION;
39
40
41
42 DFLOAT tbl_sin[TABLE_SIZE];
43 DFLOAT tbl_cos[TABLE_SIZE];
44
45 int ON(char *optval);
46 int OFF(char *optval);
47 int f2i(DFLOAT f);
48 DFLOAT findDir(DFLOAT x, DFLOAT y);
49 void Make_table(void);
50
ON(char * optval)51 int ON(char *optval)
52 {
53 return (strncasecmp(optval, "true", 4) == 0
54 || strncasecmp(optval, "on", 2) == 0
55 || strncasecmp(optval, "yes", 3) == 0);
56 }
57
58
OFF(char * optval)59 int OFF(char *optval)
60 {
61 return (strncasecmp(optval, "false", 5) == 0
62 || strncasecmp(optval, "off", 3) == 0
63 || strncasecmp(optval, "no", 2) == 0);
64 }
65
66
mod(int x,int y)67 int mod(int x, int y)
68 {
69 if (x >= y || x < 0)
70 x = x - y*(x/y);
71
72 if (x < 0)
73 x += y;
74
75 return x;
76 }
77
78
f2i(DFLOAT f)79 int f2i(DFLOAT f)
80 {
81 return (f < 0) ? -(int)(0.5f - f) : (int)(f + 0.5f);
82 }
83
findDir(DFLOAT x,DFLOAT y)84 DFLOAT findDir(DFLOAT x, DFLOAT y)
85 {
86 DFLOAT angle;
87
88 if (x != 0.0 || y != 0.0)
89 angle = atan2(y, x) / (2 * PI);
90 else
91 angle = 0.0;
92
93 if (angle < 0)
94 angle++;
95 return angle * RES;
96 }
97
98
rfrac(void)99 double rfrac(void)
100 {
101 /*
102 * Return a pseudo-random value in the range { 0.0 <= x < 1.0 }.
103 * Use randomMT() which returns a 32 bit PRN and multiply by 1/(1<<32).
104 */
105 return (double) randomMT() * 0.00000000023283064365386962890625;
106 }
107
108
Make_table(void)109 void Make_table(void)
110 {
111 int i;
112
113 for (i = 0; i < TABLE_SIZE; i++) {
114 tbl_sin[i] = sin(i * (2.0 * PI / TABLE_SIZE));
115 tbl_cos[i] = cos(i * (2.0 * PI / TABLE_SIZE));
116 }
117 }
118
119