1 /**************************************************************************
2 * weather.c -- routines to model weather
4 * Written by Curtis Olson, started July 1997.
6 * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * (Log is kept at end of this file)
24 **************************************************************************/
41 #include <Aircraft/aircraft.h>
42 #include <Debug/fg_debug.h>
43 #include <Math/fg_random.h>
44 #include <Weather/weather.h>
47 /* This is a record containing current weather info */
48 struct fgWEATHER current_weather;
51 /* Initialize the weather modeling subsystem */
52 void fgWeatherInit( void ) {
57 printf("Initializing weather subsystem\n");
59 /* Configure some wind */
60 /* FG_V_north_airmass = 15; */ /* ft/s =~ 10mph */
62 // fgWeatherSetVisibility(45000.0); /* in meters */
63 fgWeatherSetVisibility(32000.0); /* about 20 miles (in meters) */
67 /* Update the weather parameters for the current position */
68 void fgWeatherUpdate( void ) {
70 /* temporarily remove the code of this do-nothing routine */
72 // #ifdef FG_WEATHER_UPDATE
76 f = current_aircraft.flight;
79 /* Add some random turbulence */
80 // FG_U_gust = fg_random() * 5.0 - 2.5;
81 // FG_V_gust = fg_random() * 5.0 - 2.5;
82 // FG_W_gust = fg_random() * 5.0 - 2.5;
83 // #endif FG_WEATHER_UPDATE
87 /* Get the current visibility */
88 float fgWeatherGetVisibility( void ) {
92 return ( w->visibility );
96 /* Set the visibility and update fog parameters */
97 void fgWeatherSetVisibility( float visibility ) {
101 w->visibility = visibility; /* in meters */
102 // w->fog_density = -log(0.01 / w->visibility; /* for GL_FOG_EXP */
103 w->fog_density = sqrt( -log(0.01) ) / w->visibility; /* for GL_FOG_EXP2 */
104 xglFogf (GL_FOG_DENSITY, w->fog_density);
105 fgPrintf( FG_INPUT, FG_DEBUG,
106 "Fog density = %.4f\n", w->fog_density);
111 /* Revision 1.18 1998/10/02 12:46:50 curt
112 /* Added an "auto throttle"
114 * Revision 1.17 1998/07/20 12:51:57 curt
115 * Default visibility to about 20 miles.
117 * Revision 1.16 1998/06/12 01:00:59 curt
118 * Build only static libraries.
119 * Declare memmove/memset for Sloaris.
120 * Added support for exponetial fog, which solves for the proper density to
121 * achieve the desired visibility range.
123 * Revision 1.15 1998/04/25 22:06:34 curt
124 * Edited cvs log messages in source files ... bad bad bad!
126 * Revision 1.14 1998/02/09 15:07:54 curt
129 * Revision 1.13 1998/01/27 00:48:08 curt
130 * Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
131 * system and commandline/config file processing code.
133 * Revision 1.12 1998/01/19 19:27:22 curt
134 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
135 * This should simplify things tremendously.
137 * Revision 1.11 1998/01/19 18:40:41 curt
138 * Tons of little changes to clean up the code and to remove fatal errors
139 * when building with the c++ compiler.
141 * Revision 1.10 1997/12/30 22:22:46 curt
142 * Further integration of event manager.
144 * Revision 1.9 1997/12/30 20:48:03 curt
145 * Integrated new event manager with subsystem initializations.
147 * Revision 1.8 1997/12/11 04:43:58 curt
148 * Fixed sun vector and lighting problems. I thing the moon is now lit
151 * Revision 1.7 1997/12/10 22:37:56 curt
152 * Prepended "fg" on the name of all global structures that didn't have it yet.
153 * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
155 * Revision 1.6 1997/08/27 03:30:38 curt
156 * Changed naming scheme of basic shared structures.
158 * Revision 1.5 1997/08/22 21:34:42 curt
159 * Doing a bit of reorganizing and house cleaning.
161 * Revision 1.4 1997/08/02 16:23:55 curt
164 * Revision 1.3 1997/07/31 22:52:41 curt
165 * Working on redoing internal coordinate systems & scenery transformations.
167 * Revision 1.2 1997/07/30 16:12:44 curt
168 * Moved fg_random routines from Util/ to Math/
170 * Revision 1.1 1997/07/19 23:03:57 curt