1 // weather.hxx -- routines to model weather
3 // Written by Curtis Olson, started July 1997.
5 // Copyright (C) 1997 Curtis L. Olson - curt@me.umn.edu
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
28 // holds the current weather values
34 GLfloat fog_exp_density;
35 GLfloat fog_exp2_density;
45 inline double get_visibility() const { return visibility; }
47 inline void set_visibility( double v ) {
48 xglMatrixMode(GL_MODELVIEW);
53 fog_exp_density = -log(0.01 / visibility);
56 fog_exp2_density = sqrt( -log(0.01) ) / visibility;
58 // Set correct opengl fog density
59 xglFogf (GL_FOG_DENSITY, fog_exp2_density);
60 xglFogi( GL_FOG_MODE, GL_EXP2 );
62 // FG_LOG( FG_INPUT, FG_DEBUG, "Fog density = " << fog_density );
63 // FG_LOG( FG_INPUT, FG_INFO,
64 // "Fog exp2 density = " << fog_exp2_density );
68 extern FGWeather current_weather;
71 #endif // _WEATHER_HXX