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 (_fx && _refID != 0 && _refID != 1) {
149 SGSoundMgr *smgr = globals->get_soundmgr();
153 smgr->remove(name.str());
161 /** Cleanly remove the model
162 * and let the scenery database pager do the clean-up work.
165 FGAIBase::removeModel()
170 FGScenery* pSceneryManager = globals->get_scenery();
173 osg::ref_ptr<osg::Object> temp = _model.get();
174 pSceneryManager->get_scene_graph()->removeChild(aip.getSceneGraph());
175 // withdraw from SGModelPlacement and drop own reference (unref)
178 // pass it on to the pager, to be be deleted in the pager thread
179 pSceneryManager->getPagerSingleton()->queueDeleteRequest(temp);
183 SG_LOG(SG_AI, SG_ALERT, "AIBase: Could not unload model. Missing scenery manager!");
187 void FGAIBase::readFromScenario(SGPropertyNode* scFileNode)
192 setPath(scFileNode->getStringValue("model",
193 fgGetString("/sim/multiplay/default-model", default_model)));
195 setHeading(scFileNode->getDoubleValue("heading", 0.0));
196 setSpeed(scFileNode->getDoubleValue("speed", 0.0));
197 setAltitude(scFileNode->getDoubleValue("altitude", 0.0));
198 setLongitude(scFileNode->getDoubleValue("longitude", 0.0));
199 setLatitude(scFileNode->getDoubleValue("latitude", 0.0));
200 setBank(scFileNode->getDoubleValue("roll", 0.0));
202 SGPropertyNode* submodels = scFileNode->getChild("submodels");
205 setServiceable(submodels->getBoolValue("serviceable", false));
206 setSMPath(submodels->getStringValue("path", ""));
211 void FGAIBase::update(double dt) {
213 if (_otype == otStatic)
216 if (_otype == otBallistic)
219 ft_per_deg_lat = 366468.96 - 3717.12 * cos(pos.getLatitudeRad());
220 ft_per_deg_lon = 365228.16 * cos(pos.getLatitudeRad());
224 // update model's audio sample values
225 _fx->set_position_geod( pos );
227 SGQuatd orient = SGQuatd::fromYawPitchRollDeg(hdg, pitch, roll);
228 _fx->set_orientation( orient );
231 velocity = SGVec3d( speed_north_deg_sec, speed_east_deg_sec,
233 _fx->set_velocity( velocity );
235 else if ((_aimodel)&&(fgGetBool("/sim/sound/aimodels/enabled",false)))
237 string fxpath = _aimodel->get_sound_path();
241 props->setStringValue("sim/sound/path", _fxpath.c_str());
243 // initialize the sound configuration
244 SGSoundMgr *smgr = globals->get_soundmgr();
248 _fx = new FGFX(smgr, name.str(), props);
254 /** update LOD properties of the model */
255 void FGAIBase::updateLOD()
257 double maxRangeDetail = fgGetDouble("/sim/rendering/static-lod/ai-detailed", 10000.0);
258 double maxRangeBare = fgGetDouble("/sim/rendering/static-lod/ai-bare", 20000.0);
261 if( maxRangeDetail == 0.0 )
264 _model->setRange(0, 0.0, FLT_MAX);
265 _model->setRange(1, FLT_MAX, FLT_MAX);
269 _model->setRange(0, 0.0, maxRangeDetail);
270 _model->setRange(1, maxRangeDetail,maxRangeBare);
275 void FGAIBase::Transform() {
278 aip.setVisible(true);
279 aip.setPosition(pos);
282 aip.setOrientation(0.0, pitch, hdg);
284 aip.setOrientation(roll, pitch, hdg);
288 aip.setVisible(false);
294 bool FGAIBase::init(bool search_in_AI_path)
298 SG_LOG(SG_AI, SG_ALERT, "AIBase: Cannot initialize a model multiple times! " << model_path);
303 if(search_in_AI_path)
305 // setup a modified Options structure, with only the $fg-root/AI defined;
306 // we'll check that first, then give the normal search logic a chance.
307 // this ensures that models in AI/ are preferred to normal models, where
309 osg::ref_ptr<osgDB::ReaderWriter::Options>
310 opt(osg::clone(osgDB::Registry::instance()->getOptions(), osg::CopyOp::SHALLOW_COPY));
312 SGPath ai_path(globals->get_fg_root(), "AI");
313 opt->setDatabasePath(ai_path.str());
315 f = osgDB::findDataFile(model_path, opt.get());
319 f = simgear::SGModelLib::findDataFile(model_path);
323 f = fgGetString("/sim/multiplay/default-model", default_model);
327 _aimodel = new FGAIModelData(props);
328 osg::Node * mdl = SGModelLib::loadDeferredModel(f, props, _aimodel);
330 _model = new osg::LOD;
331 _model->setName("AI-model range animation node");
333 _model->addChild( mdl, 0, FLT_MAX );
334 _model->setCenterMode(osg::LOD::USE_BOUNDING_SPHERE_CENTER);
335 _model->setRangeMode(osg::LOD::DISTANCE_FROM_EYE_POINT);
336 // We really need low-resolution versions of AI/MP aircraft.
337 // Or at least dummy "stubs" with some default silhouette.
338 // _model->addChild( SGModelLib::loadPagedModel(fgGetString("/sim/multiplay/default-model", default_model),
339 // props, new FGNasalModelData(props)), FLT_MAX, FLT_MAX);
343 if (_model.valid() && _initialized == false) {
344 aip.init( _model.get() );
345 aip.setVisible(true);
347 globals->get_scenery()->get_scene_graph()->addChild(aip.getSceneGraph());
349 // Get the sound-path tag from the configuration file and store it
350 // in the property tree.
353 } else if (!model_path.empty()) {
354 SG_LOG(SG_AI, SG_WARN, "AIBase: Could not load model " << model_path);
355 // not properly installed...
363 void FGAIBase::initModel(osg::Node *node)
365 if (_model.valid()) {
368 props->setStringValue("submodels/path", _path.c_str());
369 SG_LOG(SG_AI, SG_DEBUG, "AIBase: submodels/path " << _path);
373 props->setStringValue("parent-name", _parent.c_str());
376 fgSetString("/ai/models/model-added", props->getPath().c_str());
377 } else if (!model_path.empty()) {
378 SG_LOG(SG_AI, SG_WARN, "AIBase: Could not load model " << model_path);
385 bool FGAIBase::isa( object_type otype ) {
386 return otype == _otype;
390 void FGAIBase::bind() {
391 props->tie("id", SGRawValueMethods<FGAIBase,int>(*this,
393 props->tie("velocities/true-airspeed-kt", SGRawValuePointer<double>(&speed));
394 props->tie("velocities/vertical-speed-fps",
395 SGRawValueMethods<FGAIBase,double>(*this,
396 &FGAIBase::_getVS_fps,
397 &FGAIBase::_setVS_fps));
399 props->tie("position/altitude-ft",
400 SGRawValueMethods<FGAIBase,double>(*this,
401 &FGAIBase::_getAltitude,
402 &FGAIBase::_setAltitude));
403 props->tie("position/latitude-deg",
404 SGRawValueMethods<FGAIBase,double>(*this,
405 &FGAIBase::_getLatitude,
406 &FGAIBase::_setLatitude));
407 props->tie("position/longitude-deg",
408 SGRawValueMethods<FGAIBase,double>(*this,
409 &FGAIBase::_getLongitude,
410 &FGAIBase::_setLongitude));
412 props->tie("position/global-x",
413 SGRawValueMethods<FGAIBase,double>(*this,
414 &FGAIBase::_getCartPosX,
416 props->tie("position/global-y",
417 SGRawValueMethods<FGAIBase,double>(*this,
418 &FGAIBase::_getCartPosY,
420 props->tie("position/global-z",
421 SGRawValueMethods<FGAIBase,double>(*this,
422 &FGAIBase::_getCartPosZ,
424 props->tie("callsign",
425 SGRawValueMethods<FGAIBase,const char*>(*this,
426 &FGAIBase::_getCallsign,
429 props->tie("orientation/pitch-deg", SGRawValuePointer<double>(&pitch));
430 props->tie("orientation/roll-deg", SGRawValuePointer<double>(&roll));
431 props->tie("orientation/true-heading-deg", SGRawValuePointer<double>(&hdg));
433 props->tie("radar/in-range", SGRawValuePointer<bool>(&in_range));
434 props->tie("radar/bearing-deg", SGRawValuePointer<double>(&bearing));
435 props->tie("radar/elevation-deg", SGRawValuePointer<double>(&elevation));
436 props->tie("radar/range-nm", SGRawValuePointer<double>(&range));
437 props->tie("radar/h-offset", SGRawValuePointer<double>(&horiz_offset));
438 props->tie("radar/v-offset", SGRawValuePointer<double>(&vert_offset));
439 props->tie("radar/x-shift", SGRawValuePointer<double>(&x_shift));
440 props->tie("radar/y-shift", SGRawValuePointer<double>(&y_shift));
441 props->tie("radar/rotation", SGRawValuePointer<double>(&rotation));
442 props->tie("radar/ht-diff-ft", SGRawValuePointer<double>(&ht_diff));
443 props->tie("subID", SGRawValuePointer<int>(&_subID));
444 props->tie("controls/lighting/nav-lights",
445 SGRawValueFunctions<bool>(_isNight));
446 props->setBoolValue("controls/lighting/beacon", true);
447 props->setBoolValue("controls/lighting/strobe", true);
448 props->setBoolValue("controls/glide-path", true);
450 props->setStringValue("controls/flight/lateral-mode", "roll");
451 props->setDoubleValue("controls/flight/target-hdg", hdg);
452 props->setDoubleValue("controls/flight/target-roll", roll);
454 props->setStringValue("controls/flight/longitude-mode", "alt");
455 props->setDoubleValue("controls/flight/target-alt", altitude_ft);
456 props->setDoubleValue("controls/flight/target-pitch", pitch);
458 props->setDoubleValue("controls/flight/target-spd", speed);
460 props->setBoolValue("sim/sound/avionics/enabled", false);
461 props->setDoubleValue("sim/sound/avionics/volume", 0.0);
462 props->setBoolValue("sim/sound/avionics/external-view", false);
463 props->setBoolValue("sim/current-view/internal", false);
467 void FGAIBase::unbind() {
469 props->untie("velocities/true-airspeed-kt");
470 props->untie("velocities/vertical-speed-fps");
472 props->untie("position/altitude-ft");
473 props->untie("position/latitude-deg");
474 props->untie("position/longitude-deg");
475 props->untie("position/global-x");
476 props->untie("position/global-y");
477 props->untie("position/global-z");
478 props->untie("callsign");
480 props->untie("orientation/pitch-deg");
481 props->untie("orientation/roll-deg");
482 props->untie("orientation/true-heading-deg");
484 props->untie("radar/in-range");
485 props->untie("radar/bearing-deg");
486 props->untie("radar/elevation-deg");
487 props->untie("radar/range-nm");
488 props->untie("radar/h-offset");
489 props->untie("radar/v-offset");
490 props->untie("radar/x-shift");
491 props->untie("radar/y-shift");
492 props->untie("radar/rotation");
493 props->untie("radar/ht-diff-ft");
495 props->untie("controls/lighting/nav-lights");
497 props->setBoolValue("/sim/controls/radar/", true);
499 // drop reference to sound effects now
503 double FGAIBase::UpdateRadar(FGAIManager* manager) {
504 bool control = fgGetBool("/sim/controls/radar", true);
506 if(!control) return 0;
508 double radar_range_ft2 = fgGetDouble("/instrumentation/radar/range");
509 bool force_on = fgGetBool("/instrumentation/radar/debug-mode", false);
510 radar_range_ft2 *= SG_NM_TO_METER * SG_METER_TO_FEET * 1.1; // + 10%
511 radar_range_ft2 *= radar_range_ft2;
513 double user_latitude = manager->get_user_latitude();
514 double user_longitude = manager->get_user_longitude();
515 double lat_range = fabs(pos.getLatitudeDeg() - user_latitude) * ft_per_deg_lat;
516 double lon_range = fabs(pos.getLongitudeDeg() - user_longitude) * ft_per_deg_lon;
517 double range_ft2 = lat_range*lat_range + lon_range*lon_range;
520 // Test whether the target is within radar range.
522 in_range = (range_ft2 && (range_ft2 <= radar_range_ft2));
524 if ( in_range || force_on ) {
525 props->setBoolValue("radar/in-range", true);
527 // copy values from the AIManager
528 double user_altitude = manager->get_user_altitude();
529 double user_heading = manager->get_user_heading();
530 double user_pitch = manager->get_user_pitch();
531 //double user_yaw = manager->get_user_yaw();
532 //double user_speed = manager->get_user_speed();
534 // calculate range to target in feet and nautical miles
535 double range_ft = sqrt( range_ft2 );
536 range = range_ft / 6076.11549;
538 // calculate bearing to target
539 if (pos.getLatitudeDeg() >= user_latitude) {
540 bearing = atan2(lat_range, lon_range) * SG_RADIANS_TO_DEGREES;
541 if (pos.getLongitudeDeg() >= user_longitude) {
542 bearing = 90.0 - bearing;
544 bearing = 270.0 + bearing;
547 bearing = atan2(lon_range, lat_range) * SG_RADIANS_TO_DEGREES;
548 if (pos.getLongitudeDeg() >= user_longitude) {
549 bearing = 180.0 - bearing;
551 bearing = 180.0 + bearing;
555 // This is an alternate way to compute bearing and distance which
556 // agrees with the original scheme within about 0.1 degrees.
558 // Point3D start( user_longitude * SGD_DEGREES_TO_RADIANS,
559 // user_latitude * SGD_DEGREES_TO_RADIANS, 0 );
560 // Point3D dest( pos.getLongitudeRad(), pos.getLatitudeRad(), 0 );
561 // double gc_bearing, gc_range;
562 // calc_gc_course_dist( start, dest, &gc_bearing, &gc_range );
563 // gc_range *= SG_METER_TO_NM;
564 // gc_bearing *= SGD_RADIANS_TO_DEGREES;
565 // printf("orig b = %.3f %.2f gc b= %.3f, %.2f\n",
566 // bearing, range, gc_bearing, gc_range);
568 // calculate look left/right to target, without yaw correction
569 horiz_offset = bearing - user_heading;
570 if (horiz_offset > 180.0) horiz_offset -= 360.0;
571 if (horiz_offset < -180.0) horiz_offset += 360.0;
573 // calculate elevation to target
574 elevation = atan2( altitude_ft - user_altitude, range_ft ) * SG_RADIANS_TO_DEGREES;
576 // calculate look up/down to target
577 vert_offset = elevation - user_pitch;
579 /* this calculation needs to be fixed, but it isn't important anyway
580 // calculate range rate
581 double recip_bearing = bearing + 180.0;
582 if (recip_bearing > 360.0) recip_bearing -= 360.0;
583 double my_horiz_offset = recip_bearing - hdg;
584 if (my_horiz_offset > 180.0) my_horiz_offset -= 360.0;
585 if (my_horiz_offset < -180.0) my_horiz_offset += 360.0;
586 rdot = (-user_speed * cos( horiz_offset * SG_DEGREES_TO_RADIANS ))
587 +(-speed * 1.686 * cos( my_horiz_offset * SG_DEGREES_TO_RADIANS ));
590 // now correct look left/right for yaw
591 // horiz_offset += user_yaw; // FIXME: WHY WOULD WE WANT TO ADD IN SIDE-SLIP HERE?
593 // calculate values for radar display
594 y_shift = range * cos( horiz_offset * SG_DEGREES_TO_RADIANS);
595 x_shift = range * sin( horiz_offset * SG_DEGREES_TO_RADIANS);
596 rotation = hdg - user_heading;
597 if (rotation < 0.0) rotation += 360.0;
598 ht_diff = altitude_ft - user_altitude;
606 * Getters and Setters
609 SGVec3d FGAIBase::getCartPosAt(const SGVec3d& _off) const {
610 // Transform that one to the horizontal local coordinate system.
611 SGQuatd hlTrans = SGQuatd::fromLonLat(pos);
613 // and postrotate the orientation of the AIModel wrt the horizontal
615 hlTrans *= SGQuatd::fromYawPitchRollDeg(hdg, pitch, roll);
617 // The offset converted to the usual body fixed coordinate system
618 // rotated to the earth fixed coordinates axis
619 SGVec3d off = hlTrans.backTransform(_off);
621 // Add the position offset of the AIModel to gain the earth centered position
622 SGVec3d cartPos = SGVec3d::fromGeod(pos);
624 return cartPos + off;
627 SGVec3d FGAIBase::getCartPos() const {
628 SGVec3d cartPos = SGVec3d::fromGeod(pos);
632 bool FGAIBase::getGroundElevationM(const SGGeod& pos, double& elev,
633 const SGMaterial** material) const {
634 return globals->get_scenery()->get_elevation_m(pos, elev, material,
638 double FGAIBase::_getCartPosX() const {
639 SGVec3d cartPos = getCartPos();
643 double FGAIBase::_getCartPosY() const {
644 SGVec3d cartPos = getCartPos();
648 double FGAIBase::_getCartPosZ() const {
649 SGVec3d cartPos = getCartPos();
653 void FGAIBase::_setLongitude( double longitude ) {
654 pos.setLongitudeDeg(longitude);
657 void FGAIBase::_setLatitude ( double latitude ) {
658 pos.setLatitudeDeg(latitude);
661 void FGAIBase::_setUserPos(){
662 userpos.setLatitudeDeg(manager->get_user_latitude());
663 userpos.setLongitudeDeg(manager->get_user_longitude());
664 userpos.setElevationM(manager->get_user_altitude() * SG_FEET_TO_METER);
667 void FGAIBase::_setSubID( int s ) {
671 bool FGAIBase::setParentNode() {
674 SG_LOG(SG_AI, SG_ALERT, "AIBase: " << _name
675 << " parent not set ");
679 const SGPropertyNode_ptr ai = fgGetNode("/ai/models", true);
681 for (int i = ai->nChildren() - 1; i >= -1; i--) {
682 SGPropertyNode_ptr model;
684 if (i < 0) { // last iteration: selected model
685 model = _selected_ac;
687 model = ai->getChild(i);
688 string path = ai->getPath();
689 const string name = model->getStringValue("name");
691 if (!model->nChildren()){
694 if (name == _parent) {
695 _selected_ac = model; // save selected model for last iteration
705 if (_selected_ac != 0){
706 const string name = _selected_ac->getStringValue("name");
709 SG_LOG(SG_AI, SG_ALERT, "AIBase: " << _name
710 << " parent not found: dying ");
717 double FGAIBase::_getLongitude() const {
718 return pos.getLongitudeDeg();
721 double FGAIBase::_getLatitude() const {
722 return pos.getLatitudeDeg();
725 double FGAIBase::_getElevationFt() const {
726 return pos.getElevationFt();
729 double FGAIBase::_getRdot() const {
733 double FGAIBase::_getVS_fps() const {
737 double FGAIBase::_get_speed_east_fps() const {
738 return speed_east_deg_sec * ft_per_deg_lon;
741 double FGAIBase::_get_speed_north_fps() const {
742 return speed_north_deg_sec * ft_per_deg_lat;
745 void FGAIBase::_setVS_fps( double _vs ) {
749 double FGAIBase::_getAltitude() const {
753 double FGAIBase::_getAltitudeAGL(SGGeod inpos, double start){
754 getGroundElevationM(SGGeod::fromGeodM(inpos, start),
755 _elevation_m, &_material);
756 return inpos.getElevationFt() - _elevation_m * SG_METER_TO_FEET;
759 bool FGAIBase::_getServiceable() const {
763 SGPropertyNode* FGAIBase::_getProps() const {
767 void FGAIBase::_setAltitude( double _alt ) {
771 bool FGAIBase::_isNight() {
772 return (fgGetFloat("/sim/time/sun-angle-rad") > 1.57);
775 bool FGAIBase::_getCollisionData() {
776 return _collision_reported;
779 bool FGAIBase::_getExpiryData() {
780 return _expiry_reported;
783 bool FGAIBase::_getImpactData() {
784 return _impact_reported;
787 double FGAIBase::_getImpactLat() const {
791 double FGAIBase::_getImpactLon() const {
795 double FGAIBase::_getImpactElevFt() const {
796 return _impact_elev * SG_METER_TO_FEET;
799 double FGAIBase::_getImpactPitch() const {
800 return _impact_pitch;
803 double FGAIBase::_getImpactRoll() const {
807 double FGAIBase::_getImpactHdg() const {
811 double FGAIBase::_getImpactSpeed() const {
812 return _impact_speed;
815 int FGAIBase::getID() const {
819 int FGAIBase::_getSubID() const {
823 double FGAIBase::_getSpeed() const {
827 double FGAIBase::_getRoll() const {
831 double FGAIBase::_getPitch() const {
835 double FGAIBase::_getHeading() const {
839 double FGAIBase::_getXOffset() const {
843 double FGAIBase::_getYOffset() const {
847 double FGAIBase::_getZOffset() const {
851 const char* FGAIBase::_getPath() const {
852 return model_path.c_str();
855 const char* FGAIBase::_getSMPath() const {
856 return _path.c_str();
859 const char* FGAIBase::_getName() const {
860 return _name.c_str();
863 const char* FGAIBase::_getCallsign() const {
864 return _callsign.c_str();
867 const char* FGAIBase::_getSubmodel() const {
868 return _submodel.c_str();
871 void FGAIBase::CalculateMach() {
872 // Calculate rho at altitude, using standard atmosphere
873 // For the temperature T and the pressure p,
874 double altitude = altitude_ft;
876 if (altitude < 36152) { // curve fits for the troposphere
877 T = 59 - 0.00356 * altitude;
878 p = 2116 * pow( ((T + 459.7) / 518.6) , 5.256);
879 } else if ( 36152 < altitude && altitude < 82345 ) { // lower stratosphere
881 p = 473.1 * pow( e , 1.73 - (0.000048 * altitude) );
882 } else { // upper stratosphere
883 T = -205.05 + (0.00164 * altitude);
884 p = 51.97 * pow( ((T + 459.7) / 389.98) , -11.388);
887 rho = p / (1718 * (T + 459.7));
889 // calculate the speed of sound at altitude
890 // a = sqrt ( g * R * (T + 459.7))
892 // a = speed of sound [ft/s]
893 // g = specific heat ratio, which is usually equal to 1.4
894 // R = specific gas constant, which equals 1716 ft-lb/slug/R
895 a = sqrt ( 1.4 * 1716 * (T + 459.7));
897 // calculate Mach number
900 // cout << "Speed(ft/s) "<< speed <<" Altitude(ft) "<< altitude << " Mach " << Mach << endl;
903 int FGAIBase::_newAIModelID() {
907 id++; // id = 0 is not allowed.
913 FGAIModelData::FGAIModelData(SGPropertyNode *root)
914 : _nasal( new FGNasalModelData(root) ),
919 FGAIModelData::~FGAIModelData()
924 void FGAIModelData::modelLoaded(const string& path, SGPropertyNode *prop, osg::Node *n)
926 const char* fxpath = prop->getStringValue("sound/path");
928 _path = string(fxpath);
930 _nasal->modelLoaded(path, prop, n);