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 <math.h>
  33
  34 #include <simgear/debug/logstream.hxx>
  35
  36 #include <Main/fg_props.hxx>
  37 #include "environment.hxx"
  38
  39
  40 FGEnvironment::FGEnvironment()
  41   : visibility_m(32000),
  42     temperature_sea_level_degc(20),
  43     pressure_sea_level_inhg(28),
  44     wind_from_heading_deg(0),
  45     wind_speed_kt(0),
  46     wind_from_north_fps(0),
  47     wind_from_east_fps(0),
  48     wind_from_down_fps(0)
  49 {
  50 }
  51
  52
  53 FGEnvironment::~FGEnvironment()
  54 {
  55 }
  56
  57
  58 double
  59 FGEnvironment::get_visibility_m () const
  60 {
  61   return visibility_m;
  62 }
  63
  64 double
  65 FGEnvironment::get_temperature_sea_level_degc () const
  66 {
  67   return temperature_sea_level_degc;
  68 }
  69
  70 double
  71 FGEnvironment::get_pressure_sea_level_inhg () const
  72 {
  73   return pressure_sea_level_inhg;
  74 }
  75
  76 double
  77 FGEnvironment::get_wind_from_heading_deg () const
  78 {
  79   return wind_from_heading_deg;
  80 }
  81
  82 double
  83 FGEnvironment::get_wind_speed_kt () const
  84 {
  85   return wind_speed_kt;
  86 }
  87
  88 double
  89 FGEnvironment::get_wind_from_north_fps () const
  90 {
  91   return wind_from_north_fps;
  92 }
  93
  94 double
  95 FGEnvironment::get_wind_from_east_fps () const
  96 {
  97   return wind_from_east_fps;
  98 }
  99
 100 double
 101 FGEnvironment::get_wind_from_down_fps () const
 102 {
 103   return wind_from_down_fps;
 104 }
 105
 106
 107
 108 void
 109 FGEnvironment::set_visibility_m (double v)
 110 {
 111   visibility_m = v;
 112 }
 113
 114 void
 115 FGEnvironment::set_temperature_sea_level_degc (double t)
 116 {
 117   temperature_sea_level_degc = t;
 118 }
 119
 120 void
 121 FGEnvironment::set_pressure_sea_level_inhg (double p)
 122 {
 123   pressure_sea_level_inhg = p;
 124 }
 125
 126 void
 127 FGEnvironment::set_wind_from_heading_deg (double h)
 128 {
 129   wind_from_heading_deg = h;
 130   _recalc_ne();
 131 }
 132
 133 void
 134 FGEnvironment::set_wind_speed_kt (double s)
 135 {
 136   wind_speed_kt = s;
 137   _recalc_ne();
 138 }
 139
 140 void
 141 FGEnvironment::set_wind_from_north_fps (double n)
 142 {
 143   wind_from_north_fps = n;
 144   _recalc_hdgspd();
 145 }
 146
 147 void
 148 FGEnvironment::set_wind_from_east_fps (double e)
 149 {
 150   wind_from_east_fps = e;
 151   _recalc_hdgspd();
 152 }
 153
 154 void
 155 FGEnvironment::set_wind_from_down_fps (double d)
 156 {
 157   wind_from_down_fps = d;
 158   _recalc_hdgspd();
 159 }
 160
 161 void
 162 FGEnvironment::_recalc_hdgspd ()
 163 {
 164   double angle_rad;
 165
 166   if (wind_from_east_fps == 0) {
 167     angle_rad = (wind_from_north_fps >= 0 ? SGD_PI/2 : -SGD_PI/2);
 168   } else {
 169     angle_rad = atan(wind_from_north_fps/wind_from_east_fps);
 170   }
 171   wind_from_heading_deg = angle_rad * SGD_RADIANS_TO_DEGREES;
 172   if (wind_from_east_fps >= 0)
 173     wind_from_heading_deg = 90 - wind_from_heading_deg;
 174   else
 175     wind_from_heading_deg = 270 - wind_from_heading_deg;
 176   if (angle_rad == 0)
 177     wind_speed_kt = fabs(wind_from_east_fps
 178                          * SG_METER_TO_NM * SG_FEET_TO_METER * 3600);
 179   else
 180     wind_speed_kt = (wind_from_north_fps / sin(angle_rad))
 181       * SG_METER_TO_NM * SG_FEET_TO_METER * 3600;
 182 }
 183
 184 void
 185 FGEnvironment::_recalc_ne ()
 186 {
 187   double speed_fps =
 188     wind_speed_kt * SG_NM_TO_METER * SG_METER_TO_FEET * (1.0/3600);
 189
 190   wind_from_north_fps = speed_fps *
 191     cos(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
 192   wind_from_east_fps = speed_fps *
 193     sin(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
 194 }
 195
 196 // end of environment.cxx
 197