src/Environment/environment.cxx

   1 // environment.cxx -- routines to model the natural environment
   2 //
   3 // Written by David Megginson, started February 2002.
   4 //
   5 // Copyright (C) 2002  David Megginson - david@megginson.com
   6 //
   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.
  11 //
  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.
  16 //
  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.
  20 //
  21 // $Id$
  22
  23
  24 #ifdef HAVE_CONFIG_H
  25 #  include <config.h>
  26 #endif
  27
  28 #ifdef HAVE_WINDOWS_H
  29 #  include <windows.h>
  30 #endif
  31
  32 #include <GL/glut.h>
  33 #include <GL/gl.h>
  34
  35 #include <math.h>
  36
  37 #include <simgear/debug/logstream.hxx>
  38 #include <simgear/math/sg_random.h>
  39
  40 #include <Main/fg_props.hxx>
  41 #include <Aircraft/aircraft.hxx>
  42 #include "environment.hxx"
  43
  44
  45 // This is a record containing current environment info
  46 FGEnvironment current_environment;
  47
  48
  49 FGEnvironment::FGEnvironment()
  50   : visibility_m(32000),
  51     wind_from_heading_deg(0),
  52     wind_speed_kt(0),
  53     wind_from_north_fps(0),
  54     wind_from_east_fps(0),
  55     wind_from_down_fps(0),
  56     fog_exp_density(0),
  57     fog_exp2_density(0)
  58 {
  59 }
  60
  61
  62 FGEnvironment::~FGEnvironment()
  63 {
  64 }
  65
  66
  67 // Initialize the environment modeling subsystem
  68 void FGEnvironment::init ()
  69 {
  70     SG_LOG( SG_GENERAL, SG_INFO, "Initializing environment subsystem");
  71 }
  72
  73
  74 void
  75 FGEnvironment::bind ()
  76 {
  77   fgTie("/environment/visibility-m", this,
  78         &FGEnvironment::get_visibility_m, &FGEnvironment::set_visibility_m);
  79   fgSetArchivable("/environment/visibility-m");
  80   fgTie("/environment/wind-from-heading-deg", this,
  81         &FGEnvironment::get_wind_from_heading_deg,
  82         &FGEnvironment::set_wind_from_heading_deg);
  83   fgTie("/environment/wind-speed-kt", this,
  84         &FGEnvironment::get_wind_speed_kt, &FGEnvironment::set_wind_speed_kt);
  85   fgTie("/environment/wind-from-north-fps", this,
  86         &FGEnvironment::get_wind_from_north_fps,
  87         &FGEnvironment::set_wind_from_north_fps);
  88   fgSetArchivable("/environment/wind-from-north-fps");
  89   fgTie("/environment/wind-from-east-fps", this,
  90         &FGEnvironment::get_wind_from_east_fps,
  91         &FGEnvironment::set_wind_from_east_fps);
  92   fgSetArchivable("/environment/wind-from-east-fps");
  93   fgTie("/environment/wind-from-down-fps", this,
  94         &FGEnvironment::get_wind_from_down_fps,
  95         &FGEnvironment::set_wind_from_down_fps);
  96   fgSetArchivable("/environment/wind-from-down-fps");
  97 }
  98
  99 void
 100 FGEnvironment::unbind ()
 101 {
 102   fgUntie("/environment/visibility-m");
 103   fgUntie("/environment/wind-from-heading-deg");
 104   fgUntie("/environment/wind-speed-kt");
 105   fgUntie("/environment/wind-from-north-fps");
 106   fgUntie("/environment/wind-from-east-fps");
 107   fgUntie("/environment/wind-from-down-fps");
 108 }
 109
 110 void FGEnvironment::update (int dt)
 111 {
 112                                 // FIXME: the FDMs should update themselves
 113   current_aircraft.fdm_state
 114     ->set_Velocities_Local_Airmass(wind_from_north_fps,
 115                                    wind_from_east_fps,
 116                                    wind_from_down_fps);
 117 }
 118
 119 void
 120 FGEnvironment::set_visibility_m (double v)
 121 {
 122         glMatrixMode(GL_MODELVIEW);
 123         // in meters
 124         visibility_m = v;
 125
 126         // for GL_FOG_EXP
 127         fog_exp_density = -log(0.01 / visibility_m);
 128
 129         // for GL_FOG_EXP2
 130         fog_exp2_density = sqrt( -log(0.01) ) / visibility_m;
 131
 132         // Set correct opengl fog density
 133         glFogf (GL_FOG_DENSITY, fog_exp2_density);
 134         glFogi( GL_FOG_MODE, GL_EXP2 );
 135
 136         // SG_LOG( SG_INPUT, SG_DEBUG, "Fog density = " << fog_density );
 137         // SG_LOG( SG_INPUT, SG_INFO,
 138         //         "Fog exp2 density = " << fog_exp2_density );
 139 }
 140
 141 void
 142 FGEnvironment::set_wind_from_heading_deg (double h)
 143 {
 144   wind_from_heading_deg = h;
 145   _recalc_ne();
 146 }
 147
 148 void
 149 FGEnvironment::set_wind_speed_kt (double s)
 150 {
 151   wind_speed_kt = s;
 152   _recalc_ne();
 153 }
 154
 155 void
 156 FGEnvironment::set_wind_from_north_fps (double n)
 157 {
 158   wind_from_north_fps = n;
 159   _recalc_hdgspd();
 160 }
 161
 162 void
 163 FGEnvironment::set_wind_from_east_fps (double e)
 164 {
 165   wind_from_east_fps = e;
 166   _recalc_hdgspd();
 167 }
 168
 169 void
 170 FGEnvironment::set_wind_from_down_fps (double d)
 171 {
 172   wind_from_down_fps = d;
 173   _recalc_hdgspd();
 174 }
 175
 176 void
 177 FGEnvironment::_recalc_hdgspd ()
 178 {
 179   double angle_rad;
 180
 181   if (wind_from_east_fps == 0) {
 182     angle_rad = (wind_from_north_fps >= 0 ? SGD_PI/2 : -SGD_PI/2);
 183   } else {
 184     angle_rad = atan(wind_from_north_fps/wind_from_east_fps);
 185   }
 186   wind_from_heading_deg = angle_rad * SGD_RADIANS_TO_DEGREES;
 187   if (wind_from_east_fps >= 0)
 188     wind_from_heading_deg = 90 - wind_from_heading_deg;
 189   else
 190     wind_from_heading_deg = 270 - wind_from_heading_deg;
 191   if (angle_rad == 0)
 192     wind_speed_kt = fabs(wind_from_east_fps
 193                          * SG_METER_TO_NM * SG_FEET_TO_METER * 3600);
 194   else
 195     wind_speed_kt = (wind_from_north_fps / sin(angle_rad))
 196       * SG_METER_TO_NM * SG_FEET_TO_METER * 3600;
 197 }
 198
 199 void
 200 FGEnvironment::_recalc_ne ()
 201 {
 202   double speed_fps =
 203     wind_speed_kt * SG_NM_TO_METER * SG_METER_TO_FEET * (1.0/3600);
 204
 205   wind_from_north_fps = speed_fps *
 206     cos(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
 207   wind_from_east_fps = speed_fps *
 208     sin(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
 209 }
 210
 211 // end of environment.cxx
 212