src/Instrumentation/vertical_speed_indicator.cxx

   1 // vertical_speed_indicator.cxx - a regular VSI.
   2 // Written by David Megginson, started 2002.
   3 //
   4 // This file is in the Public Domain and comes with no warranty.
   5
   6 #include <simgear/math/interpolater.hxx>
   7
   8 #include "vertical_speed_indicator.hxx"
   9 #include <Main/fg_props.hxx>
  10 #include <Main/util.hxx>
  11
  12
  13 VerticalSpeedIndicator::VerticalSpeedIndicator ()
  14     : _internal_pressure_inhg(29.92)
  15 {
  16 }
  17
  18 VerticalSpeedIndicator::~VerticalSpeedIndicator ()
  19 {
  20 }
  21
  22 void
  23 VerticalSpeedIndicator::init ()
  24 {
  25     _serviceable_node =
  26         fgGetNode("/instrumentation/vertical-speed-indicator/serviceable",
  27                   true);
  28     _pressure_node =
  29         fgGetNode("/systems/static/pressure-inhg", true);
  30     _speed_node =
  31         fgGetNode("/instrumentation/vertical-speed-indicator/indicated-speed-fpm",
  32                   true);
  33
  34                                 // Initialize at ambient pressure
  35     _internal_pressure_inhg = _pressure_node->getDoubleValue();
  36 }
  37
  38 void
  39 VerticalSpeedIndicator::update (double dt)
  40 {
  41                                 // model taken from steam.cxx, with change
  42                                 // from 10000 to 10500 for manual factor
  43     if (_serviceable_node->getBoolValue()) {
  44         double pressure = _pressure_node->getDoubleValue();
  45         _speed_node
  46             ->setDoubleValue((_internal_pressure_inhg - pressure) * 10500);
  47         _internal_pressure_inhg =
  48             fgGetLowPass(_internal_pressure_inhg,
  49                          _pressure_node->getDoubleValue(),
  50                          dt/6.0);
  51     }
  52 }
  53
  54 // end of vertical_speed_indicator.cxx