1 // FGAIBase - abstract base class for AI objects
2 // Written by David Culp, started Nov 2003, based on
3 // David Luff's FGAIEntity class.
4 // - davidculp2@comcast.net
6 // With additions by Mathias Froehlich & Vivian Meazza 2004 -2007
8 // This program is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU General Public License as
10 // published by the Free Software Foundation; either version 2 of the
11 // License, or (at your option) any later version.
13 // This program is distributed in the hope that it will be useful, but
14 // WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
29 #include <simgear/compiler.h>
33 #include <osg/ref_ptr>
35 #include <osgDB/FileUtils>
37 #include <simgear/math/SGMath.hxx>
38 #include <simgear/misc/sg_path.hxx>
39 #include <simgear/scene/model/modellib.hxx>
40 #include <simgear/scene/util/SGNodeMasks.hxx>
41 #include <simgear/sound/soundmgr_openal.hxx>
42 #include <simgear/debug/logstream.hxx>
43 #include <simgear/props/props.hxx>
45 #include <Main/globals.hxx>
46 #include <Scenery/scenery.hxx>
47 #include <Scripting/NasalSys.hxx>
48 #include <Sound/fg_fx.hxx>
51 #include "AIManager.hxx"
53 const char *default_model = "Models/Geometry/glider.ac";
54 const double FGAIBase::e = 2.71828183;
55 const double FGAIBase::lbs_to_slugs = 0.031080950172; //conversion factor
57 using namespace simgear;
59 FGAIBase::FGAIBase(object_type ot, bool enableHot) :
64 model_removed( fgGetNode("/ai/models/model-removed", true) ),
75 _refID( _newAIModelID() ),
83 tgt_heading = hdg = tgt_altitude_ft = tgt_speed = 0.0;
84 tgt_roll = roll = tgt_pitch = tgt_yaw = tgt_vs = vs = pitch = 0.0;
85 bearing = elevation = range = rdot = 0.0;
86 x_shift = y_shift = rotation = 0.0;
92 _impact_reported = false;
93 _collision_reported = false;
94 _expiry_reported = false;
106 userpos = SGGeod::fromDeg(0, 0);
108 pos = SGGeod::fromDeg(0, 0);
111 speed_north_deg_sec = 0;
112 speed_east_deg_sec = 0;
132 // explicitly disable HOT for (most) AI models
134 aip.getSceneGraph()->setNodeMask(~SG_NODEMASK_TERRAIN_BIT);
137 FGAIBase::~FGAIBase() {
138 // Unregister that one at the scenery manager
142 SGPropertyNode* parent = props->getParent();
145 model_removed->setStringValue(props->getPath());
148 if (_refID != 0 && _refID != 1) {
149 SGSoundMgr *smgr = globals->get_soundmgr();
150 smgr->remove("aifx:"+_refID);
157 /** Cleanly remove the model
158 * and let the scenery database pager do the clean-up work.
161 FGAIBase::removeModel()
163 FGScenery* pSceneryManager = globals->get_scenery();
166 osg::ref_ptr<osg::Object> temp = _model.get();
167 pSceneryManager->get_scene_graph()->removeChild(aip.getSceneGraph());
168 // withdraw from SGModelPlacement and drop own reference (unref)
171 // pass it on to the pager, to be be deleted in the pager thread
172 pSceneryManager->getPagerSingleton()->queueDeleteRequest(temp);
176 SG_LOG(SG_AI, SG_ALERT, "AIBase: Could not unload model. Missing scenery manager!");
180 void FGAIBase::readFromScenario(SGPropertyNode* scFileNode)
185 setPath(scFileNode->getStringValue("model",
186 fgGetString("/sim/multiplay/default-model", default_model)));
188 setHeading(scFileNode->getDoubleValue("heading", 0.0));
189 setSpeed(scFileNode->getDoubleValue("speed", 0.0));
190 setAltitude(scFileNode->getDoubleValue("altitude", 0.0));
191 setLongitude(scFileNode->getDoubleValue("longitude", 0.0));
192 setLatitude(scFileNode->getDoubleValue("latitude", 0.0));
193 setBank(scFileNode->getDoubleValue("roll", 0.0));
195 SGPropertyNode* submodels = scFileNode->getChild("submodels");
198 setServiceable(submodels->getBoolValue("serviceable", false));
199 setSMPath(submodels->getStringValue("path", ""));
204 void FGAIBase::update(double dt) {
206 if (_otype == otStatic)
209 if (_otype == otBallistic)
212 ft_per_deg_lat = 366468.96 - 3717.12 * cos(pos.getLatitudeRad());
213 ft_per_deg_lon = 365228.16 * cos(pos.getLatitudeRad());
217 // update model's audio sample values
218 _fx->set_position_geod( pos );
220 SGQuatd orient = SGQuatd::fromYawPitchRollDeg(hdg, pitch, roll);
221 _fx->set_orientation( orient );
224 velocity = SGVec3d( speed_north_deg_sec, speed_east_deg_sec, pitch*speed );
225 _fx->set_velocity( velocity );
229 string fxpath = _aimodel->get_sound_path();
233 props->setStringValue("sim/sound/path", _fxpath.c_str());
235 // initialize the sound configuration
236 SGSoundMgr *smgr = globals->get_soundmgr();
237 _fx = new FGFX(smgr, "aifx:"+_refID, props);
243 /** update LOD properties of the model */
244 void FGAIBase::updateLOD()
246 double maxRangeDetail = fgGetDouble("/sim/rendering/static-lod/ai-detailed", 10000.0);
247 double maxRangeBare = fgGetDouble("/sim/rendering/static-lod/ai-bare", 20000.0);
250 if( maxRangeDetail == 0.0 )
253 _model->setRange(0, 0.0, FLT_MAX);
254 _model->setRange(1, FLT_MAX, FLT_MAX);
258 _model->setRange(0, 0.0, maxRangeDetail);
259 _model->setRange(1, maxRangeDetail,maxRangeBare);
264 void FGAIBase::Transform() {
267 aip.setVisible(true);
268 aip.setPosition(pos);
271 aip.setOrientation(0.0, pitch, hdg);
273 aip.setOrientation(roll, pitch, hdg);
277 aip.setVisible(false);
283 bool FGAIBase::init(bool search_in_AI_path) {
286 if(search_in_AI_path)
288 // setup a modified Options structure, with only the $fg-root/AI defined;
289 // we'll check that first, then give the normal search logic a chance.
290 // this ensures that models in AI/ are preferred to normal models, where
292 osg::ref_ptr<osgDB::ReaderWriter::Options>
293 opt(osg::clone(osgDB::Registry::instance()->getOptions(), osg::CopyOp::SHALLOW_COPY));
295 SGPath ai_path(globals->get_fg_root(), "AI");
296 opt->setDatabasePath(ai_path.str());
298 f = osgDB::findDataFile(model_path, opt.get());
302 f = simgear::SGModelLib::findDataFile(model_path);
306 f = fgGetString("/sim/multiplay/default-model", default_model);
310 _aimodel = new FGAIModelData(props);
311 osg::Node * mdl = SGModelLib::loadDeferredModel(f, props, _aimodel);
315 // reinit, dump the old model
319 _model = new osg::LOD;
320 _model->setName("AI-model range animation node");
322 _model->addChild( mdl, 0, FLT_MAX );
323 _model->setCenterMode(osg::LOD::USE_BOUNDING_SPHERE_CENTER);
324 _model->setRangeMode(osg::LOD::DISTANCE_FROM_EYE_POINT);
325 // We really need low-resolution versions of AI/MP aircraft.
326 // Or at least dummy "stubs" with some default silhouette.
327 // _model->addChild( SGModelLib::loadPagedModel(fgGetString("/sim/multiplay/default-model", default_model),
328 // props, new FGNasalModelData(props)), FLT_MAX, FLT_MAX);
332 if (_model.valid() && _initialized == false) {
333 aip.init( _model.get() );
334 aip.setVisible(true);
336 globals->get_scenery()->get_scene_graph()->addChild(aip.getSceneGraph());
338 // Get the sound-path tag from the configuration file and store it
339 // in the property tree.
342 } else if (!model_path.empty()) {
343 SG_LOG(SG_AI, SG_WARN, "AIBase: Could not load model " << model_path);
344 // not properly installed...
352 void FGAIBase::initModel(osg::Node *node)
354 if (_model.valid()) {
357 props->setStringValue("submodels/path", _path.c_str());
358 SG_LOG(SG_AI, SG_DEBUG, "AIBase: submodels/path " << _path);
362 props->setStringValue("parent-name", _parent.c_str());
365 fgSetString("/ai/models/model-added", props->getPath().c_str());
366 } else if (!model_path.empty()) {
367 SG_LOG(SG_AI, SG_WARN, "AIBase: Could not load model " << model_path);
374 bool FGAIBase::isa( object_type otype ) {
375 return otype == _otype;
379 void FGAIBase::bind() {
380 props->tie("id", SGRawValueMethods<FGAIBase,int>(*this,
382 props->tie("velocities/true-airspeed-kt", SGRawValuePointer<double>(&speed));
383 props->tie("velocities/vertical-speed-fps",
384 SGRawValueMethods<FGAIBase,double>(*this,
385 &FGAIBase::_getVS_fps,
386 &FGAIBase::_setVS_fps));
388 props->tie("position/altitude-ft",
389 SGRawValueMethods<FGAIBase,double>(*this,
390 &FGAIBase::_getAltitude,
391 &FGAIBase::_setAltitude));
392 props->tie("position/latitude-deg",
393 SGRawValueMethods<FGAIBase,double>(*this,
394 &FGAIBase::_getLatitude,
395 &FGAIBase::_setLatitude));
396 props->tie("position/longitude-deg",
397 SGRawValueMethods<FGAIBase,double>(*this,
398 &FGAIBase::_getLongitude,
399 &FGAIBase::_setLongitude));
401 props->tie("position/global-x",
402 SGRawValueMethods<FGAIBase,double>(*this,
403 &FGAIBase::_getCartPosX,
405 props->tie("position/global-y",
406 SGRawValueMethods<FGAIBase,double>(*this,
407 &FGAIBase::_getCartPosY,
409 props->tie("position/global-z",
410 SGRawValueMethods<FGAIBase,double>(*this,
411 &FGAIBase::_getCartPosZ,
413 props->tie("callsign",
414 SGRawValueMethods<FGAIBase,const char*>(*this,
415 &FGAIBase::_getCallsign,
418 props->tie("orientation/pitch-deg", SGRawValuePointer<double>(&pitch));
419 props->tie("orientation/roll-deg", SGRawValuePointer<double>(&roll));
420 props->tie("orientation/true-heading-deg", SGRawValuePointer<double>(&hdg));
422 props->tie("radar/in-range", SGRawValuePointer<bool>(&in_range));
423 props->tie("radar/bearing-deg", SGRawValuePointer<double>(&bearing));
424 props->tie("radar/elevation-deg", SGRawValuePointer<double>(&elevation));
425 props->tie("radar/range-nm", SGRawValuePointer<double>(&range));
426 props->tie("radar/h-offset", SGRawValuePointer<double>(&horiz_offset));
427 props->tie("radar/v-offset", SGRawValuePointer<double>(&vert_offset));
428 props->tie("radar/x-shift", SGRawValuePointer<double>(&x_shift));
429 props->tie("radar/y-shift", SGRawValuePointer<double>(&y_shift));
430 props->tie("radar/rotation", SGRawValuePointer<double>(&rotation));
431 props->tie("radar/ht-diff-ft", SGRawValuePointer<double>(&ht_diff));
432 props->tie("subID", SGRawValuePointer<int>(&_subID));
433 props->tie("controls/lighting/nav-lights",
434 SGRawValueFunctions<bool>(_isNight));
435 props->setBoolValue("controls/lighting/beacon", true);
436 props->setBoolValue("controls/lighting/strobe", true);
437 props->setBoolValue("controls/glide-path", true);
439 props->setStringValue("controls/flight/lateral-mode", "roll");
440 props->setDoubleValue("controls/flight/target-hdg", hdg);
441 props->setDoubleValue("controls/flight/target-roll", roll);
443 props->setStringValue("controls/flight/longitude-mode", "alt");
444 props->setDoubleValue("controls/flight/target-alt", altitude_ft);
445 props->setDoubleValue("controls/flight/target-pitch", pitch);
447 props->setDoubleValue("controls/flight/target-spd", speed);
449 props->setBoolValue("sim/sound/avionics/enabled", false);
450 props->setDoubleValue("sim/sound/avionics/volume", 0.0);
451 props->setBoolValue("sim/sound/avionics/external-view", false);
452 props->setBoolValue("sim/current-view/internal", false);
456 void FGAIBase::unbind() {
458 props->untie("velocities/true-airspeed-kt");
459 props->untie("velocities/vertical-speed-fps");
461 props->untie("position/altitude-ft");
462 props->untie("position/latitude-deg");
463 props->untie("position/longitude-deg");
464 props->untie("position/global-x");
465 props->untie("position/global-y");
466 props->untie("position/global-z");
467 props->untie("callsign");
469 props->untie("orientation/pitch-deg");
470 props->untie("orientation/roll-deg");
471 props->untie("orientation/true-heading-deg");
473 props->untie("radar/in-range");
474 props->untie("radar/bearing-deg");
475 props->untie("radar/elevation-deg");
476 props->untie("radar/range-nm");
477 props->untie("radar/h-offset");
478 props->untie("radar/v-offset");
479 props->untie("radar/x-shift");
480 props->untie("radar/y-shift");
481 props->untie("radar/rotation");
482 props->untie("radar/ht-diff-ft");
484 props->untie("controls/lighting/nav-lights");
486 props->setBoolValue("/sim/controls/radar/", true);
490 double FGAIBase::UpdateRadar(FGAIManager* manager) {
491 bool control = fgGetBool("/sim/controls/radar", true);
493 if(!control) return 0;
495 double radar_range_ft2 = fgGetDouble("/instrumentation/radar/range");
496 bool force_on = fgGetBool("/instrumentation/radar/debug-mode", false);
497 radar_range_ft2 *= SG_NM_TO_METER * SG_METER_TO_FEET * 1.1; // + 10%
498 radar_range_ft2 *= radar_range_ft2;
500 double user_latitude = manager->get_user_latitude();
501 double user_longitude = manager->get_user_longitude();
502 double lat_range = fabs(pos.getLatitudeDeg() - user_latitude) * ft_per_deg_lat;
503 double lon_range = fabs(pos.getLongitudeDeg() - user_longitude) * ft_per_deg_lon;
504 double range_ft2 = lat_range*lat_range + lon_range*lon_range;
507 // Test whether the target is within radar range.
509 in_range = (range_ft2 && (range_ft2 <= radar_range_ft2));
511 if ( in_range || force_on ) {
512 props->setBoolValue("radar/in-range", true);
514 // copy values from the AIManager
515 double user_altitude = manager->get_user_altitude();
516 double user_heading = manager->get_user_heading();
517 double user_pitch = manager->get_user_pitch();
518 //double user_yaw = manager->get_user_yaw();
519 //double user_speed = manager->get_user_speed();
521 // calculate range to target in feet and nautical miles
522 double range_ft = sqrt( range_ft2 );
523 range = range_ft / 6076.11549;
525 // calculate bearing to target
526 if (pos.getLatitudeDeg() >= user_latitude) {
527 bearing = atan2(lat_range, lon_range) * SG_RADIANS_TO_DEGREES;
528 if (pos.getLongitudeDeg() >= user_longitude) {
529 bearing = 90.0 - bearing;
531 bearing = 270.0 + bearing;
534 bearing = atan2(lon_range, lat_range) * SG_RADIANS_TO_DEGREES;
535 if (pos.getLongitudeDeg() >= user_longitude) {
536 bearing = 180.0 - bearing;
538 bearing = 180.0 + bearing;
542 // This is an alternate way to compute bearing and distance which
543 // agrees with the original scheme within about 0.1 degrees.
545 // Point3D start( user_longitude * SGD_DEGREES_TO_RADIANS,
546 // user_latitude * SGD_DEGREES_TO_RADIANS, 0 );
547 // Point3D dest( pos.getLongitudeRad(), pos.getLatitudeRad(), 0 );
548 // double gc_bearing, gc_range;
549 // calc_gc_course_dist( start, dest, &gc_bearing, &gc_range );
550 // gc_range *= SG_METER_TO_NM;
551 // gc_bearing *= SGD_RADIANS_TO_DEGREES;
552 // printf("orig b = %.3f %.2f gc b= %.3f, %.2f\n",
553 // bearing, range, gc_bearing, gc_range);
555 // calculate look left/right to target, without yaw correction
556 horiz_offset = bearing - user_heading;
557 if (horiz_offset > 180.0) horiz_offset -= 360.0;
558 if (horiz_offset < -180.0) horiz_offset += 360.0;
560 // calculate elevation to target
561 elevation = atan2( altitude_ft - user_altitude, range_ft ) * SG_RADIANS_TO_DEGREES;
563 // calculate look up/down to target
564 vert_offset = elevation - user_pitch;
566 /* this calculation needs to be fixed, but it isn't important anyway
567 // calculate range rate
568 double recip_bearing = bearing + 180.0;
569 if (recip_bearing > 360.0) recip_bearing -= 360.0;
570 double my_horiz_offset = recip_bearing - hdg;
571 if (my_horiz_offset > 180.0) my_horiz_offset -= 360.0;
572 if (my_horiz_offset < -180.0) my_horiz_offset += 360.0;
573 rdot = (-user_speed * cos( horiz_offset * SG_DEGREES_TO_RADIANS ))
574 +(-speed * 1.686 * cos( my_horiz_offset * SG_DEGREES_TO_RADIANS ));
577 // now correct look left/right for yaw
578 // horiz_offset += user_yaw; // FIXME: WHY WOULD WE WANT TO ADD IN SIDE-SLIP HERE?
580 // calculate values for radar display
581 y_shift = range * cos( horiz_offset * SG_DEGREES_TO_RADIANS);
582 x_shift = range * sin( horiz_offset * SG_DEGREES_TO_RADIANS);
583 rotation = hdg - user_heading;
584 if (rotation < 0.0) rotation += 360.0;
585 ht_diff = altitude_ft - user_altitude;
593 * Getters and Setters
596 SGVec3d FGAIBase::getCartPosAt(const SGVec3d& _off) const {
597 // Transform that one to the horizontal local coordinate system.
598 SGQuatd hlTrans = SGQuatd::fromLonLat(pos);
600 // and postrotate the orientation of the AIModel wrt the horizontal
602 hlTrans *= SGQuatd::fromYawPitchRollDeg(hdg, pitch, roll);
604 // The offset converted to the usual body fixed coordinate system
605 // rotated to the earth fixed coordinates axis
606 SGVec3d off = hlTrans.backTransform(_off);
608 // Add the position offset of the AIModel to gain the earth centered position
609 SGVec3d cartPos = SGVec3d::fromGeod(pos);
611 return cartPos + off;
614 SGVec3d FGAIBase::getCartPos() const {
615 SGVec3d cartPos = SGVec3d::fromGeod(pos);
619 bool FGAIBase::getGroundElevationM(const SGGeod& pos, double& elev,
620 const SGMaterial** material) const {
621 return globals->get_scenery()->get_elevation_m(pos, elev, material,
625 double FGAIBase::_getCartPosX() const {
626 SGVec3d cartPos = getCartPos();
630 double FGAIBase::_getCartPosY() const {
631 SGVec3d cartPos = getCartPos();
635 double FGAIBase::_getCartPosZ() const {
636 SGVec3d cartPos = getCartPos();
640 void FGAIBase::_setLongitude( double longitude ) {
641 pos.setLongitudeDeg(longitude);
644 void FGAIBase::_setLatitude ( double latitude ) {
645 pos.setLatitudeDeg(latitude);
648 void FGAIBase::_setUserPos(){
649 userpos.setLatitudeDeg(manager->get_user_latitude());
650 userpos.setLongitudeDeg(manager->get_user_longitude());
651 userpos.setElevationM(manager->get_user_altitude() * SG_FEET_TO_METER);
654 void FGAIBase::_setSubID( int s ) {
658 bool FGAIBase::setParentNode() {
661 SG_LOG(SG_AI, SG_ALERT, "AIBase: " << _name
662 << " parent not set ");
666 const SGPropertyNode_ptr ai = fgGetNode("/ai/models", true);
668 for (int i = ai->nChildren() - 1; i >= -1; i--) {
669 SGPropertyNode_ptr model;
671 if (i < 0) { // last iteration: selected model
672 model = _selected_ac;
674 model = ai->getChild(i);
675 string path = ai->getPath();
676 const string name = model->getStringValue("name");
678 if (!model->nChildren()){
681 if (name == _parent) {
682 _selected_ac = model; // save selected model for last iteration
692 if (_selected_ac != 0){
693 const string name = _selected_ac->getStringValue("name");
696 SG_LOG(SG_AI, SG_ALERT, "AIBase: " << _name
697 << " parent not found: dying ");
704 double FGAIBase::_getLongitude() const {
705 return pos.getLongitudeDeg();
708 double FGAIBase::_getLatitude() const {
709 return pos.getLatitudeDeg();
712 double FGAIBase::_getElevationFt() const {
713 return pos.getElevationFt();
716 double FGAIBase::_getRdot() const {
720 double FGAIBase::_getVS_fps() const {
724 double FGAIBase::_get_speed_east_fps() const {
725 return speed_east_deg_sec * ft_per_deg_lon;
728 double FGAIBase::_get_speed_north_fps() const {
729 return speed_north_deg_sec * ft_per_deg_lat;
732 void FGAIBase::_setVS_fps( double _vs ) {
736 double FGAIBase::_getAltitude() const {
740 double FGAIBase::_getAltitudeAGL(SGGeod inpos, double start){
741 getGroundElevationM(SGGeod::fromGeodM(inpos, start),
742 _elevation_m, &_material);
743 return inpos.getElevationFt() - _elevation_m * SG_METER_TO_FEET;
746 bool FGAIBase::_getServiceable() const {
750 SGPropertyNode* FGAIBase::_getProps() const {
754 void FGAIBase::_setAltitude( double _alt ) {
758 bool FGAIBase::_isNight() {
759 return (fgGetFloat("/sim/time/sun-angle-rad") > 1.57);
762 bool FGAIBase::_getCollisionData() {
763 return _collision_reported;
766 bool FGAIBase::_getExpiryData() {
767 return _expiry_reported;
770 bool FGAIBase::_getImpactData() {
771 return _impact_reported;
774 double FGAIBase::_getImpactLat() const {
778 double FGAIBase::_getImpactLon() const {
782 double FGAIBase::_getImpactElevFt() const {
783 return _impact_elev * SG_METER_TO_FEET;
786 double FGAIBase::_getImpactPitch() const {
787 return _impact_pitch;
790 double FGAIBase::_getImpactRoll() const {
794 double FGAIBase::_getImpactHdg() const {
798 double FGAIBase::_getImpactSpeed() const {
799 return _impact_speed;
802 int FGAIBase::getID() const {
806 int FGAIBase::_getSubID() const {
810 double FGAIBase::_getSpeed() const {
814 double FGAIBase::_getRoll() const {
818 double FGAIBase::_getPitch() const {
822 double FGAIBase::_getHeading() const {
826 double FGAIBase::_getXOffset() const {
830 double FGAIBase::_getYOffset() const {
834 double FGAIBase::_getZOffset() const {
838 const char* FGAIBase::_getPath() const {
839 return model_path.c_str();
842 const char* FGAIBase::_getSMPath() const {
843 return _path.c_str();
846 const char* FGAIBase::_getName() const {
847 return _name.c_str();
850 const char* FGAIBase::_getCallsign() const {
851 return _callsign.c_str();
854 const char* FGAIBase::_getSubmodel() const {
855 return _submodel.c_str();
858 void FGAIBase::CalculateMach() {
859 // Calculate rho at altitude, using standard atmosphere
860 // For the temperature T and the pressure p,
861 double altitude = altitude_ft;
863 if (altitude < 36152) { // curve fits for the troposphere
864 T = 59 - 0.00356 * altitude;
865 p = 2116 * pow( ((T + 459.7) / 518.6) , 5.256);
866 } else if ( 36152 < altitude && altitude < 82345 ) { // lower stratosphere
868 p = 473.1 * pow( e , 1.73 - (0.000048 * altitude) );
869 } else { // upper stratosphere
870 T = -205.05 + (0.00164 * altitude);
871 p = 51.97 * pow( ((T + 459.7) / 389.98) , -11.388);
874 rho = p / (1718 * (T + 459.7));
876 // calculate the speed of sound at altitude
877 // a = sqrt ( g * R * (T + 459.7))
879 // a = speed of sound [ft/s]
880 // g = specific heat ratio, which is usually equal to 1.4
881 // R = specific gas constant, which equals 1716 ft-lb/slug/R
882 a = sqrt ( 1.4 * 1716 * (T + 459.7));
884 // calculate Mach number
887 // cout << "Speed(ft/s) "<< speed <<" Altitude(ft) "<< altitude << " Mach " << Mach << endl;
890 int FGAIBase::_newAIModelID() {
894 id++; // id = 0 is not allowed.
900 FGAIModelData::FGAIModelData(SGPropertyNode *root)
901 : _nasal( new FGNasalModelData(root) ),
906 FGAIModelData::~FGAIModelData()
911 void FGAIModelData::modelLoaded(const string& path, SGPropertyNode *prop, osg::Node *n)
913 const char* fxpath = prop->getStringValue("sound/path");
915 string sound_path = string(fxpath);
916 if (sound_path != "") {
917 _path = "/AI/"+sound_path;
920 _nasal->modelLoaded(path, prop, n);