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flightgear/src/Instrumentation/dme.cxx
Torsten Dreyer b42841ccd2 Add formatted KDI572/574 properties 
Syd Adams:
I've added an update to dme.cxx /dme.hxx.
It adds a formatted KDI572-574/nm , min and kt string properties meant
for text animations for these instruments.Existing instruments will funtion
as usual, no breaks. The purpose here is to eliminate yet another nasal
workaround which usually needs to repeat some of what the code already does.
The 3 properties are empty when the dme is off (no need to check for power),
dashes when powered up but no source , out of range ,etc.
The are formatted to the KDI-572/573/574 limits ...
0-99.9/100-389 for distance to station,
0-99 minutes for time to station,
groundspeed 0-999 kt.
2015-02-11 08:35:31 +01:00

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7.7 KiB
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// dme.cxx - distance-measuring equipment.
// Written by David Megginson, started 2003.
//
// This file is in the Public Domain and comes with no warranty.
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <simgear/compiler.h>
#include <simgear/sg_inlines.h>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/math/sg_random.h>
#include <simgear/sound/sample_group.hxx>
#include <Main/fg_props.hxx>
#include <Navaids/navlist.hxx>
#include <Sound/audioident.hxx>
#include "dme.hxx"
#include <cstdio>
/**
* Adjust the range.
*
* Start by calculating the radar horizon based on the elevation
* difference, then clamp to the maximum, then add a fudge for
* borderline reception.
*/
static double
adjust_range (double transmitter_elevation_ft, double aircraft_altitude_ft,
double max_range_nm)
{
double delta_elevation_ft =
fabs(aircraft_altitude_ft - transmitter_elevation_ft);
double range_nm = 1.23 * sqrt(delta_elevation_ft);
if (range_nm > max_range_nm)
range_nm = max_range_nm;
else if (range_nm < 20.0)
range_nm = 20.0;
double rand = sg_random();
return range_nm + (range_nm * rand * rand);
}
namespace {
class DMEFilter : public FGNavList::TypeFilter
{
public:
DMEFilter() :
TypeFilter(FGPositioned::DME),
_locEnabled(fgGetBool("/sim/realism/dme-fallback-to-loc", true))
{
if (_locEnabled) {
_mintype = FGPositioned::ILS;
}
}
virtual bool pass(FGPositioned* pos) const
{
switch (pos->type()) {
case FGPositioned::DME: return true;
case FGPositioned::ILS:
case FGPositioned::LOC: return _locEnabled;
default: return false;
}
}
private:
const bool _locEnabled;
};
} // of anonymous namespace
DME::DME ( SGPropertyNode *node )
: _last_distance_nm(0),
_last_frequency_mhz(-1),
_time_before_search_sec(0),
_navrecord(NULL),
_name(node->getStringValue("name", "dme")),
_num(node->getIntValue("number", 0)),
_audioIdent(NULL)
{
}
DME::~DME ()
{
delete _audioIdent;
}
void
DME::init ()
{
std::string branch;
branch = "/instrumentation/" + _name;
SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
_serviceable_node = node->getChild("serviceable", 0, true);
_electrical_node = fgGetNode("/systems/electrical/outputs/dme", true);
SGPropertyNode *fnode = node->getChild("frequencies", 0, true);
_source_node = fnode->getChild("source", 0, true);
_frequency_node = fnode->getChild("selected-mhz", 0, true);
_in_range_node = node->getChild("in-range", 0, true);
_distance_node = node->getChild("indicated-distance-nm", 0, true);
_speed_node = node->getChild("indicated-ground-speed-kt", 0, true);
_time_node = node->getChild("indicated-time-min", 0, true);
double d = node->getDoubleValue( "volume", 1.0 );
_volume_node = node->getChild("volume", 0, true);
_volume_node->setDoubleValue( d );
bool b = node->getBoolValue( "ident", false );
_ident_btn_node = node->getChild("ident", 0, true);
_ident_btn_node->setBoolValue( b );
SGPropertyNode *subnode = node->getChild("KDI572-574", 0, true);
_distance_string = subnode->getChild("nm",0, true);
_distance_string->setStringValue("---");
_speed_string = subnode->getChild("kt", 0, true);
_speed_string->setStringValue("---");
_time_string = subnode->getChild("min",0, true);
_time_string->setStringValue("--");
std::ostringstream temp;
temp << _name << "-ident-" << _num;
if( NULL == _audioIdent )
_audioIdent = new DMEAudioIdent( temp.str() );
_audioIdent->init();
reinit();
}
void
DME::reinit ()
{
_time_before_search_sec = 0;
}
void
DME::update (double delta_time_sec)
{
if( delta_time_sec < SGLimitsd::min() )
return; //paused
char tmp[16];
// Figure out the source
const char * source = _source_node->getStringValue();
if (source[0] == '\0') {
std::string branch;
branch = "/instrumentation/" + _name + "/frequencies/selected-mhz";
_source_node->setStringValue(branch.c_str());
source = _source_node->getStringValue();
}
// Get the frequency
double frequency_mhz = fgGetDouble(source, 108.0);
if (frequency_mhz != _last_frequency_mhz) {
_time_before_search_sec = 0;
_last_frequency_mhz = frequency_mhz;
}
_frequency_node->setDoubleValue(frequency_mhz);
// Get the aircraft position
// On timeout, scan again
_time_before_search_sec -= delta_time_sec;
if (_time_before_search_sec < 0) {
_time_before_search_sec = 1.0;
SGGeod pos(globals->get_aircraft_position());
DMEFilter filter;
_navrecord = FGNavList::findByFreq(frequency_mhz, pos, &filter);
}
// If it's off, don't bother.
if (!_serviceable_node->getBoolValue() ||
!_electrical_node->getBoolValue()){
_last_distance_nm = 0;
_in_range_node->setBoolValue(false);
_distance_node->setDoubleValue(0);
_speed_node->setDoubleValue(0);
_time_node->setDoubleValue(0);
_audioIdent->setIdent("", 0.0 );
_distance_string->setStringValue("");
_speed_string->setStringValue("");
_time_string->setStringValue("");
return;
}
// If it's on, but invalid source,don't bother.
if (NULL == _navrecord ){
_distance_string->setStringValue("---");
_speed_string->setStringValue("---");
_time_string->setStringValue("--");
return;
}
// Calculate the distance to the transmitter
double distance_nm = dist(_navrecord->cart(),
globals->get_aircraft_position_cart()) * SG_METER_TO_NM;
double range_nm = adjust_range(_navrecord->get_elev_ft(),
globals->get_aircraft_position().getElevationFt(),
_navrecord->get_range());
if (distance_nm <= range_nm) {
double volume = _volume_node->getDoubleValue();
if( false == _ident_btn_node->getBoolValue() )
volume = 0.0;
_audioIdent->setIdent(_navrecord->ident(), volume );
double speed_kt = (fabs(distance_nm - _last_distance_nm) *
((1 / delta_time_sec) * 3600.0));
_last_distance_nm = distance_nm;
_in_range_node->setBoolValue(true);
double tmp_dist = distance_nm - _navrecord->get_multiuse();
if ( tmp_dist < 0.0 ) {
tmp_dist = 0.0;
}
_distance_node->setDoubleValue( tmp_dist );
if ( tmp_dist >389 ) tmp_dist = 389;
if ( tmp_dist >= 100.0) {
snprintf ( tmp,16,"%3.0f",tmp_dist);
} else {
snprintf ( tmp,16,"%2.1f",tmp_dist);
}
_distance_string->setStringValue(tmp);
_speed_node->setDoubleValue(speed_kt);
double spd = speed_kt;
if(spd>999) spd=999;
snprintf ( tmp,16,"%3.0f",spd);
_speed_string->setStringValue(tmp);
if (SGLimitsd::min() < fabs(speed_kt)){
double tm = distance_nm/speed_kt*60.0;
_time_node->setDoubleValue(tm);
if (tm >99) tm= 99;
snprintf ( tmp,16,"%2.0f",tm);
_time_string->setStringValue(tmp);
}
} else {
_last_distance_nm = 0;
_in_range_node->setBoolValue(false);
_distance_node->setDoubleValue(0);
_distance_string->setStringValue("---");
_speed_node->setDoubleValue(0);
_speed_string->setStringValue("---");
_time_node->setDoubleValue(0);
_time_string->setStringValue("--");
_audioIdent->setIdent("", 0.0 );
}
_audioIdent->update( delta_time_sec );
}
// end of dme.cxx
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