]> git.mxchange.org Git - flightgear.git/blobdiff - src/AIModel/AIAircraft.cxx
Slightly altered calling sequence ensures AI aircraft are removed from
[flightgear.git] / src / AIModel / AIAircraft.cxx
index 80c0879d32b51ef20c8c020c689012ccaaeb3268..05860b60339eb1961a3738cd4d810668bd10d06a 100644 (file)
@@ -16,7 +16,7 @@
 //
 // You should have received a copy of the GNU General Public License
 // along with this program; if not, write to the Free Software
-// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 #ifdef HAVE_CONFIG_H
 #  include <config.h>
 #ifdef _MSC_VER
 #  include <float.h>
 #  define finite _finite
+#elif defined(__sun) || defined(sgi)
+#  include <ieeefp.h>
 #endif
 
 SG_USING_STD(string);
 
 #include "AIAircraft.hxx"
-   static string tempReg;
-//
-// accel, decel, climb_rate, descent_rate, takeoff_speed, climb_speed,
-// cruise_speed, descent_speed, land_speed
-//
-const FGAIAircraft::PERF_STRUCT FGAIAircraft::settings[] = {
-    // light aircraft
-    {2.0, 2.0,  450.0, 1000.0,  70.0,  80.0, 100.0,  80.0,  60.0},
-    // ww2_fighter
-    {4.0, 2.0, 3000.0, 1500.0, 110.0, 180.0, 250.0, 200.0, 100.0},
-    // jet_transport
-    {5.0, 2.0, 3000.0, 1500.0, 140.0, 300.0, 430.0, 300.0, 130.0},
-    // jet_fighter
-    {7.0, 3.0, 4000.0, 2000.0, 150.0, 350.0, 500.0, 350.0, 150.0},
-    // tanker
-    {5.0, 2.0, 3000.0, 1500.0, 140.0, 300.0, 430.0, 300.0, 130.0}
-};
-
-
-FGAIAircraft::FGAIAircraft(FGAIManager* mgr, FGAISchedule *ref) {
-  trafficRef = ref;
-  if (trafficRef)
-    groundOffset = trafficRef->getGroundOffset();
-  else
-    groundOffset = 0;
-   manager = mgr;   
-   _type_str = "aircraft";
-   _otype = otAircraft;
-   fp = 0;
-   dt_count = 0;
-   dt_elev_count = 0;
-   use_perf_vs = true;
-   isTanker = false;
-
-   // set heading and altitude locks
-   hdg_lock = false;
-   alt_lock = false;
-   roll = 0;
-   headingChangeRate = 0.0;
+#include "performancedata.hxx"
+#include "performancedb.hxx"
+
+//#include <Airports/trafficcontroller.hxx>
+
+static string tempReg;
+
+class AI_OutOfSight{};
+class FP_Inactive{};
+
+FGAIAircraft::FGAIAircraft(FGAISchedule *ref) : FGAIBase(otAircraft) {
+    trafficRef = ref;
+    if (trafficRef) {
+        groundOffset = trafficRef->getGroundOffset();
+       setCallSign(trafficRef->getCallSign());
+    }
+    else
+        groundOffset = 0;
+
+    fp = 0;
+    controller = 0;
+    prevController = 0;
+    dt_count = 0;
+    dt_elev_count = 0;
+    use_perf_vs = true;
+
+    no_roll = false;
+    tgt_speed = 0;
+    speed = 0;
+    groundTargetSpeed = 0;
+
+    // set heading and altitude locks
+    hdg_lock = false;
+    alt_lock = false;
+    roll = 0;
+    headingChangeRate = 0.0;
+
+    holdPos = false;
+
+    _performance = 0; //TODO initialize to JET_TRANSPORT from PerformanceDB
+    
 }
 
 
 FGAIAircraft::~FGAIAircraft() {
+    //delete fp;
+    if (controller)
+        controller->signOff(getID());
 }
 
 
-bool FGAIAircraft::init() {
-   refuel_node = fgGetNode("systems/refuel/contact", true);
-   return FGAIBase::init();
+void FGAIAircraft::readFromScenario(SGPropertyNode* scFileNode) {
+    if (!scFileNode)
+        return;
+
+    FGAIBase::readFromScenario(scFileNode);
+
+    setPerformance(scFileNode->getStringValue("class", "jet_transport"));
+    setFlightPlan(scFileNode->getStringValue("flightplan"),
+                  scFileNode->getBoolValue("repeat", false));
+    setCallSign(scFileNode->getStringValue("callsign"));
 }
 
+
 void FGAIAircraft::bind() {
     FGAIBase::bind();
 
     props->tie("controls/gear/gear-down",
                SGRawValueMethods<FGAIAircraft,bool>(*this,
-                                              &FGAIAircraft::_getGearDown));
-#if 0
-    props->getNode("controls/lighting/landing-lights", true)
-           ->alias("controls/gear/gear-down");
-#endif
+                                                    &FGAIAircraft::_getGearDown));
 }
 
+
 void FGAIAircraft::unbind() {
     FGAIBase::unbind();
 
     props->untie("controls/gear/gear-down");
-#if 0
-    props->getNode("controls/lighting/landing-lights")->unalias();
-#endif
 }
 
 
 void FGAIAircraft::update(double dt) {
+    FGAIBase::update(dt);
+    Run(dt);
+    Transform();
+}
 
-   FGAIBase::update(dt);
-   Run(dt);
-   Transform();
-}
-
-void FGAIAircraft::SetPerformance(const PERF_STRUCT *ps) {
-   
-   performance = ps;
-} 
-
-
-void FGAIAircraft::Run(double dt) {
-
-   FGAIAircraft::dt = dt;
-
-   if (fp) 
-     {
-       time_t now = time(NULL) + fgGetLong("/sim/time/warp");
-       ProcessFlightPlan(dt, now);
-       if (now < fp->getStartTime())
-        {
-          // Do execute Ground elev for inactive aircraft, so they
-          // Are repositioned to the correct ground altitude when the user flies within visibility range.
-          if (no_roll)
-            {
-              Transform();         // make sure aip is initialized.
-              getGroundElev(dt); // make sure it's exectuted first time around, so force a large dt value
-              //getGroundElev(dt); // Need to do this twice.
-              //cerr << trafficRef->getRegistration() << " Setting altitude to " << tgt_altitude << endl;
-              setAltitude(tgt_altitude);
-            }
-          return;
-        }
-     }
-  
-   double turn_radius_ft;
-   double turn_circum_ft;
-   double speed_north_deg_sec;
-   double speed_east_deg_sec;
-   double dist_covered_ft;
-   double alpha;
-
-   // adjust speed
-   double speed_diff; //= tgt_speed - speed;
-   if (!no_roll)
-     {
-       speed_diff = tgt_speed - speed;
-     }
-   else
-     {
-       speed_diff = groundTargetSpeed - speed;
-     }
-   if (fabs(speed_diff) > 0.2) {
-     if (speed_diff > 0.0) speed += performance->accel * dt;
-     if (speed_diff < 0.0) {
-       if (no_roll) { // was (!no_roll) but seems more logical this way (ground brakes).
-           speed -= performance->decel * dt * 3;
-        } else {
-           speed -= performance->decel * dt;
-        }
-     }
-   } 
-   
-   // convert speed to degrees per second
-   speed_north_deg_sec = cos( hdg / SG_RADIANS_TO_DEGREES )
-                          * speed * 1.686 / ft_per_deg_lat;
-   speed_east_deg_sec  = sin( hdg / SG_RADIANS_TO_DEGREES )
-                          * speed * 1.686 / ft_per_deg_lon;
-
-   // set new position
-   pos.setlat( pos.lat() + speed_north_deg_sec * dt);
-   pos.setlon( pos.lon() + speed_east_deg_sec * dt); 
-   //if (!(finite(pos.lat()) && finite(pos.lon())))
-   //  {
-   //    cerr << "Position is not finite" << endl;
-   //    cerr << "speed = " << speed << endl;
-   //    cerr << "dt" << dt << endl;
-   //    cerr << "heading " << hdg << endl;
-   //    cerr << "speed east " << speed_east_deg_sec << endl;
-   //    cerr << "speed nrth " << speed_north_deg_sec << endl;
-   //    cerr << "deg_lat    " << ft_per_deg_lat << endl;
-   //    cerr << "deg_lon    " << ft_per_deg_lon << endl;
-   //  }
-
-   // adjust heading based on current bank angle
-   if (roll == 0.0) 
-     roll = 0.01;
-   if (roll != 0.0) {
-     // double turnConstant;
-     //if (no_roll)
-     //  turnConstant = 0.0088362;
-     //else 
-     //  turnConstant = 0.088362;
-     // If on ground, calculate heading change directly
-     if (no_roll) {
-       double headingDiff = fabs(hdg-tgt_heading);
-      
-       if (headingDiff > 180)
-        headingDiff = fabs(headingDiff - 360);
-       groundTargetSpeed = tgt_speed - (tgt_speed * (headingDiff/45));
-       if (sign(groundTargetSpeed) != sign(tgt_speed))
-        groundTargetSpeed = 0.21 * sign(tgt_speed); // to prevent speed getting stuck in 'negative' mode
-       if (headingDiff > 30.0)
-        {
-          
-          headingChangeRate += dt * sign(roll); // invert if pushed backward
-          // Print some debug statements to find out why aircraft may get stuck
-          // forever turning
-          //if (trafficRef->getDepartureAirport()->getId() == string("EHAM"))
-          //  {
-          //cerr << "Turning : " << trafficRef->getRegistration()
-          //cerr <<  " Speed = " << speed << " Heading " << hdg 
-          //<< " Target Heading " << tgt_heading 
-          //   << " Lead Distance " <<  fp->getLeadDistance()
-          //   << " Distance to go " 
-          //   << fp->getDistanceToGo(pos.lat(), pos.lon(), fp->getCurrentWaypoint())
-          //   << "waypoint name " << fp->getCurrentWaypoint()->name
-          //   << endl;
-          //}
-          if (headingChangeRate > 30) 
-            { 
-              headingChangeRate = 30;
-            }
-          else if (headingChangeRate < -30)
-            {
-              headingChangeRate = -30;
-            }
-        }
-       else
-        {
-          if (fabs(headingChangeRate) > headingDiff)
-            headingChangeRate = headingDiff*sign(roll);
-          else
-            headingChangeRate += dt * sign(roll);
-        }
-       hdg += headingChangeRate * dt;
-       //cerr << "On ground. Heading: " << hdg << ". Target Heading: " << tgt_heading << ". Target speed: " << groundTargetSpeed << ". heading change rate" << headingChangeRate << endl;
-     }
-     else {
-       if (fabs(speed) > 1.0) {
-        turn_radius_ft = 0.088362 * speed * speed
-          / tan( fabs(roll) / SG_RADIANS_TO_DEGREES );
-       }
-       else
-        {
-          turn_radius_ft = 1.0; // Check if turn_radius_ft == 0; this might lead to a division by 0.
-        }
-       turn_circum_ft = SGD_2PI * turn_radius_ft;
-       dist_covered_ft = speed * 1.686 * dt; 
-       alpha = dist_covered_ft / turn_circum_ft * 360.0;
-       hdg += alpha * sign(roll);
-     }
-     while ( hdg > 360.0 ) {
-       hdg -= 360.0;
-       spinCounter++;
-     }
-     while ( hdg < 0.0) 
-       {
-        hdg += 360.0;
-        spinCounter--;
-       }
-   }
-     
-   
-   // adjust target bank angle if heading lock engaged
-   if (hdg_lock) {
-     double bank_sense = 0.0;
-     double diff = fabs(hdg - tgt_heading);
-     if (diff > 180) diff = fabs(diff - 360);
-     double sum = hdg + diff;
-     if (sum > 360.0) sum -= 360.0;
-     if (fabs(sum - tgt_heading) < 1.0) {
-       bank_sense = 1.0;   // right turn
-     } else {
-       bank_sense = -1.0;  // left turn
-     } 
-     if (diff < 30) {
-         tgt_roll = diff * bank_sense; 
-     } else {
-         tgt_roll = 30.0 * bank_sense;
-     }
-     if ((fabs((double) spinCounter) > 1) && (diff > 30))
-       {
-        tgt_speed *= 0.999; // Ugly hack: If aircraft get stuck, they will continually spin around.
-        // The only way to resolve this is to make them slow down. 
-        //if (tempReg.empty())
-        //  tempReg = trafficRef->getRegistration();
-        //if (trafficRef->getRegistration() == tempReg)
-        //  {
-        //    cerr << trafficRef->getRegistration() 
-        //       << " appears to be spinning: " << spinCounter << endl
-        //       << " speed          " << speed << endl
-        //       << " heading        " << hdg << endl
-        //       << " lead distance  " << fp->getLeadDistance() << endl
-        //       << " waypoint       " << fp->getCurrentWaypoint()->name
-        //       << " target heading " << tgt_heading << endl
-        //       << " lead in angle  " << fp->getLeadInAngle()<< endl
-        //       << " roll           " << roll << endl
-        //       << " target_roll    " << tgt_roll << endl;
-            
-        //  }
-       }
-   }
-
-   // adjust bank angle, use 9 degrees per second
-   double bank_diff = tgt_roll - roll;
-   if (fabs(bank_diff) > 0.2) {
-     if (bank_diff > 0.0) roll += 9.0 * dt;
-     if (bank_diff < 0.0) roll -= 9.0 * dt;
-     //while (roll > 180) roll -= 360;
-     //while (roll < 180) roll += 360;
-   }
-
-   // adjust altitude (meters) based on current vertical speed (fpm)
-   altitude += vs / 60.0 * dt;
-   pos.setelev(altitude * SG_FEET_TO_METER);  
-   double altitude_ft = altitude;
-
-   // adjust target Altitude, based on ground elevation when on ground
-   if (no_roll)
-     {
-       getGroundElev(dt);
+void FGAIAircraft::setPerformance(const std::string& acclass) {
+     static PerformanceDB perfdb; //TODO make it a global service
+     setPerformance(perfdb.getDataFor(acclass));
+  }
+
+
+ void FGAIAircraft::setPerformance(PerformanceData *ps) {
+     _performance = ps;
+  }
+
+
+ void FGAIAircraft::Run(double dt) {
+      FGAIAircraft::dt = dt;
+
+     try {
+         updatePrimaryTargetValues(); // target hdg, alt, speed
      }
-   // find target vertical speed if altitude lock engaged
-   if (alt_lock && use_perf_vs) {
-     if (altitude_ft < tgt_altitude) {
-       tgt_vs = tgt_altitude - altitude_ft;
-       if (tgt_vs > performance->climb_rate)
-         tgt_vs = performance->climb_rate;
-     } else {
-       tgt_vs = tgt_altitude - altitude_ft;
-       if (tgt_vs  < (-performance->descent_rate))
-         tgt_vs = -performance->descent_rate;
+     catch (AI_OutOfSight) {
+         return;
      }
-   }
-
-   if (alt_lock && !use_perf_vs) {
-     double max_vs = 4*(tgt_altitude - altitude);
-     double min_vs = 100;
-     if (tgt_altitude < altitude) min_vs = -100.0;
-     if ((fabs(tgt_altitude - altitude) < 1500.0) && 
-         (fabs(max_vs) < fabs(tgt_vs))) tgt_vs = max_vs;
-     if (fabs(tgt_vs) < fabs(min_vs)) tgt_vs = min_vs;
-   }   
-
-   // adjust vertical speed
-   double vs_diff = tgt_vs - vs;
-   if (fabs(vs_diff) > 10.0) {
-     if (vs_diff > 0.0) {
-       vs += 900.0 * dt;
-       if (vs > tgt_vs) vs = tgt_vs;
-     } else {
-       vs -= 400.0 * dt;
-       if (vs < tgt_vs) vs = tgt_vs;
+     catch (FP_Inactive) {
+         return;
      }
-   }   
-   
-   // match pitch angle to vertical speed
-   if (vs > 0){
-     pitch = vs * 0.005;
-   } else {
-     pitch = vs * 0.002;
-   }
-
-   //###########################//
-   // do calculations for radar //
-   //###########################//
-   double range_ft2 = UpdateRadar(manager);
-
-   //************************************//
-   // Tanker code                        //
-   //************************************//
-
-   if ( isTanker) {
-     if ( (range_ft2 < 250.0 * 250.0) &&
-          (y_shift > 0.0)    &&
-          (elevation > 0.0) ) {
-       refuel_node->setBoolValue(true);
-     } else {
-       refuel_node->setBoolValue(false);
-     } 
-   }
-}
+
+     handleATCRequests(); // ATC also has a word to say
+     updateSecondaryTargetValues(); // target roll, vertical speed, pitch
+     updateActualState(); 
+     UpdateRadar(manager);
+  }
+
 
 
 void FGAIAircraft::AccelTo(double speed) {
-   tgt_speed = speed;
+    tgt_speed = speed;
 }
 
 
 void FGAIAircraft::PitchTo(double angle) {
-   tgt_pitch = angle;
-   alt_lock = false;
+    tgt_pitch = angle;
+    alt_lock = false;
 }
 
 
 void FGAIAircraft::RollTo(double angle) {
-   tgt_roll = angle;
-   hdg_lock = false; 
+    tgt_roll = angle;
+    hdg_lock = false;
 }
 
 
 void FGAIAircraft::YawTo(double angle) {
-   tgt_yaw = angle;
+    tgt_yaw = angle;
 }
 
 
-void FGAIAircraft::ClimbTo(double altitude) {
-   tgt_altitude = altitude;
-   alt_lock = true;
+void FGAIAircraft::ClimbTo(double alt_ft ) {
+    tgt_altitude_ft = alt_ft;
+    alt_lock = true;
 }
 
 
 void FGAIAircraft::TurnTo(double heading) {
-   tgt_heading = heading;
-   hdg_lock = true;
+    tgt_heading = heading;
+    hdg_lock = true;
 }
 
 
 double FGAIAircraft::sign(double x) {
-  if ( x < 0.0 ) { return -1.0; }
-  else { return 1.0; }
+    if (x == 0.0)
+        return x;
+    else
+        return x/fabs(x);
 }
 
+
+void FGAIAircraft::setFlightPlan(const std::string& flightplan, bool repeat) {
+    if (!flightplan.empty()) {
+        FGAIFlightPlan* fp = new FGAIFlightPlan(flightplan);
+        fp->setRepeat(repeat);
+        SetFlightPlan(fp);
+    }
+}
+
+
 void FGAIAircraft::SetFlightPlan(FGAIFlightPlan *f) {
-  fp = f;
+    delete fp;
+    fp = f;
 }
 
-void FGAIAircraft::ProcessFlightPlan( double dt, time_t now ) 
-{
-  bool eraseWaypoints;
-  if (trafficRef)
-    {
-//       FGAirport *arr;
-//       FGAirport *dep;
-      eraseWaypoints = true;
-//       cerr << trafficRef->getRegistration();
-//       cerr << "Departure airport " << endl;
-//       dep = trafficRef->getDepartureAirport();
-//       if (dep)
-//     cerr << dep->getId() << endl;
-//       cerr << "Arrival   airport " << endl;
-//       arr = trafficRef->getArrivalAirport();
-//       if (arr)
-//     cerr << arr->getId() <<endl << endl;;
-     }
-  else
-    eraseWaypoints = false;
-
-  //cerr << "Processing Flightplan" << endl;
-  FGAIFlightPlan::waypoint* prev = 0; // the one behind you
-  FGAIFlightPlan::waypoint* curr = 0; // the one ahead
-  FGAIFlightPlan::waypoint* next = 0; // the next plus 1
-  prev = fp->getPreviousWaypoint();
-  curr = fp->getCurrentWaypoint();
-  next = fp->getNextWaypoint();
-  dt_count += dt;
-  
-  if (!prev) {  //beginning of flightplan, do this initialization once
-    //setBank(0.0);
+
+void FGAIAircraft::ProcessFlightPlan( double dt, time_t now ) {
+
+    // the one behind you
+    FGAIFlightPlan::waypoint* prev = 0;
+    // the one ahead
+    FGAIFlightPlan::waypoint* curr = 0;
+    // the next plus 1
+    FGAIFlightPlan::waypoint* next = 0;
+
+    prev = fp->getPreviousWaypoint();
+    curr = fp->getCurrentWaypoint();
+    next = fp->getNextWaypoint();
+
+    dt_count += dt;
+
+    ///////////////////////////////////////////////////////////////////////////
+    // Initialize the flightplan
+    //////////////////////////////////////////////////////////////////////////
+    if (!prev) {
+        handleFirstWaypoint();
+        return;
+    }                            // end of initialization
+    if (! fpExecutable(now))
+          return;
+    dt_count = 0;
+
+    if (! leadPointReached(curr)) {
+        controlHeading(curr);
+        controlSpeed(curr, next);
+    } else {
+        if (curr->finished)      //end of the flight plan
+        {
+            if (fp->getRepeat())
+                fp->restart();
+            else
+                setDie(true);
+            return;
+        }
+
+        if (next) {
+            //TODO more intelligent method in AIFlightPlan, no need to send data it already has :-)
+            tgt_heading = fp->getBearing(curr, next);
+            spinCounter = 0;
+        }
+
+        //TODO let the fp handle this (loading of next leg)
+        fp->IncrementWaypoint((bool) trafficRef);
+        if (!(fp->getNextWaypoint()) && trafficRef)
+            loadNextLeg();
+
+        prev = fp->getPreviousWaypoint();
+        curr = fp->getCurrentWaypoint();
+        next = fp->getNextWaypoint();
+
+        // Now that we have incremented the waypoints, excute some traffic manager specific code
+        if (trafficRef) {
+            //TODO isn't this best executed right at the beginning?
+            if (! aiTrafficVisible()) {
+                setDie(true);
+                return;
+            }
+
+            if (! handleAirportEndPoints(prev, now)) {
+                setDie(true);
+                return;
+            }
+
+            announcePositionToController();
+
+        }
+
+        if (next) {
+            fp->setLeadDistance(speed, tgt_heading, curr, next);
+        }
+
+        if (!(prev->on_ground))  // only update the tgt altitude from flightplan if not on the ground
+        {
+            tgt_altitude_ft = prev->altitude;
+            if (curr->crossat > -1000.0) {
+                use_perf_vs = false;
+                tgt_vs = (curr->crossat - altitude_ft) / (fp->getDistanceToGo(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr)
+                         / 6076.0 / speed*60.0);
+                tgt_altitude_ft = curr->crossat;
+            } else {
+                use_perf_vs = true;
+            }
+        }
+        tgt_speed = prev->speed;
+        hdg_lock = alt_lock = true;
+        no_roll = prev->on_ground;
+    }
+}
+
+
+void FGAIAircraft::initializeFlightPlan() {
+}
+
+
+bool FGAIAircraft::_getGearDown() const {
+    return _performance->gearExtensible(this);
+}
+
+
+void FGAIAircraft::loadNextLeg() {
+
+    int leg;
+    if ((leg = fp->getLeg())  == 10) {
+        trafficRef->next();
+        setCallSign(trafficRef->getCallSign());
+       //props->setStringValue("callsign", callsign.c_str());
+        leg = 1;
+        fp->setLeg(leg);
+    }
+
+    FGAirport *dep = trafficRef->getDepartureAirport();
+    FGAirport *arr = trafficRef->getArrivalAirport();
+    if (!(dep && arr)) {
+        setDie(true);
+
+    } else {
+        double cruiseAlt = trafficRef->getCruiseAlt() * 100;
+
+        fp->create (dep,
+                    arr,
+                    leg,
+                    cruiseAlt,           //(trafficRef->getCruiseAlt() * 100), // convert from FL to feet
+                    trafficRef->getSpeed(),
+                    _getLatitude(),
+                    _getLongitude(),
+                    false,
+                    trafficRef->getRadius(),
+                    trafficRef->getFlightType(),
+                    acType,
+                    company);
+    }
+}
+
+
+// Note: This code is copied from David Luff's AILocalTraffic
+// Warning - ground elev determination is CPU intensive
+// Either this function or the logic of how often it is called
+// will almost certainly change.
+
+void FGAIAircraft::getGroundElev(double dt) {
+    dt_elev_count += dt;
+
+    // Update minimally every three secs, but add some randomness
+    // to prevent all IA objects doing this in synchrony
+    if (dt_elev_count < (3.0) + (rand() % 10))
+        return;
+
+    dt_elev_count = 0;
+
+    // Only do the proper hitlist stuff if we are within visible range of the viewer.
+    if (!invisible) {
+        double visibility_meters = fgGetDouble("/environment/visibility-m");
+
+        FGViewer* vw = globals->get_current_view();
+        double course, distance;
+
+        SGWayPoint current(pos.getLongitudeDeg(), pos.getLatitudeDeg(), 0);
+        SGWayPoint view (vw->getLongitude_deg(), vw->getLatitude_deg(), 0);
+        view.CourseAndDistance(current, &course, &distance);
+        if (distance > visibility_meters) {
+            //aip.getSGLocation()->set_cur_elev_m(aptElev);
+            return;
+        }
+
+        // FIXME: make sure the pos.lat/pos.lon values are in degrees ...
+        double range = 500.0;
+        if (!globals->get_tile_mgr()->scenery_available(pos.getLatitudeDeg(), pos.getLongitudeDeg(), range)) {
+            // Try to shedule tiles for that position.
+            globals->get_tile_mgr()->update( aip.getSGLocation(), range );
+        }
+
+        // FIXME: make sure the pos.lat/pos.lon values are in degrees ...
+        double alt;
+        if (globals->get_scenery()->get_elevation_m(pos.getLatitudeDeg(), pos.getLongitudeDeg(), 20000.0, alt, 0))
+            tgt_altitude_ft = alt * SG_METER_TO_FEET;
+    }
+}
+
+
+void FGAIAircraft::doGroundAltitude() {
+    if (fabs(altitude_ft - (tgt_altitude_ft+groundOffset)) > 1000.0)
+        altitude_ft = (tgt_altitude_ft + groundOffset);
+    else
+        altitude_ft += 0.1 * ((tgt_altitude_ft+groundOffset) - altitude_ft);
+}
+
+
+void FGAIAircraft::announcePositionToController() {
+    if (trafficRef) {
+        int leg = fp->getLeg();
+
+        // Note that leg was been incremented after creating the current leg, so we should use
+        // leg numbers here that are one higher than the number that is used to create the leg
+        //
+        switch (leg) {
+        case 3:              // Taxiing to runway
+            if (trafficRef->getDepartureAirport()->getDynamics()->getGroundNetwork()->exists())
+                controller = trafficRef->getDepartureAirport()->getDynamics()->getGroundNetwork();
+            break;
+        case 4:              //Take off tower controller
+            if (trafficRef->getDepartureAirport()->getDynamics()) {
+                controller = trafficRef->getDepartureAirport()->getDynamics()->getTowerController();
+                //if (trafficRef->getDepartureAirport()->getId() == "EHAM") {
+                //cerr << trafficRef->getCallSign() << " at runway " << fp->getRunway() << "Ready for departure "
+                //   << trafficRef->getFlightType() << " to " << trafficRef->getArrivalAirport()->getId() << endl;
+                //  if (controller == 0) {
+                //cerr << "Error in assigning controller at " << trafficRef->getDepartureAirport()->getId() << endl;
+                //}
+
+            } else {
+                cerr << "Error: Could not find Dynamics at airport : " << trafficRef->getDepartureAirport()->getId() << endl;
+            }
+            break;
+        case 9:              // Taxiing for parking
+            if (trafficRef->getArrivalAirport()->getDynamics()->getGroundNetwork()->exists())
+                controller = trafficRef->getArrivalAirport()->getDynamics()->getGroundNetwork();
+            break;
+        default:
+            controller = 0;
+            break;
+        }
+
+        if ((controller != prevController) && (prevController != 0)) {
+            prevController->signOff(getID());
+            string callsign =  trafficRef->getCallSign();
+            if ( trafficRef->getHeavy())
+                callsign += "Heavy";
+            switch (leg) {
+            case 3:
+                //cerr << callsign << " ready to taxi to runway " << fp->getRunway() << endl;
+                break;
+            case 4:
+                //cerr << callsign << " at runway " << fp->getRunway() << "Ready for take-off. "
+                //     << trafficRef->getFlightRules() << " to " << trafficRef->getArrivalAirport()->getId()
+                //     << "(" << trafficRef->getArrivalAirport()->getName() << ")."<< endl;
+                break;
+            }
+        }
+        prevController = controller;
+        if (controller) {
+            controller->announcePosition(getID(), fp, fp->getCurrentWaypoint()->routeIndex,
+                                         _getLatitude(), _getLongitude(), hdg, speed, altitude_ft,
+                                         trafficRef->getRadius(), leg, trafficRef->getCallSign());
+        }
+    }
+}
+
+
+void FGAIAircraft::processATC(FGATCInstruction instruction) {
+    if (instruction.getCheckForCircularWait()) {
+        // This is not exactly an elegant solution, 
+        // but at least it gives me a chance to check
+        // if circular waits are resolved.
+        // For now, just take the offending aircraft 
+        // out of the scene
+       setDie(true);
+        // a more proper way should be - of course - to
+        // let an offending aircraft take an evasive action
+        // for instance taxi back a little bit.
+    }
+    //cerr << "Processing ATC instruction (not Implimented yet)" << endl;
+    if (instruction.getHoldPattern   ()) {}
+
+    // Hold Position
+    if (instruction.getHoldPosition  ()) {
+        if (!holdPos) {
+            holdPos = true;
+        }
+        AccelTo(0.0);
+    } else {
+        if (holdPos) {
+            //if (trafficRef)
+            // cerr << trafficRef->getCallSign() << " Resuming Taxi " << endl;
+            holdPos = false;
+        }
+        // Change speed Instruction. This can only be excecuted when there is no
+        // Hold position instruction.
+        if (instruction.getChangeSpeed   ()) {
+            //  if (trafficRef)
+            //cerr << trafficRef->getCallSign() << " Changing Speed " << endl;
+            AccelTo(instruction.getSpeed());
+        } else {
+            if (fp) AccelTo(fp->getPreviousWaypoint()->speed);
+        }
+    }
+    if (instruction.getChangeHeading ()) {
+        hdg_lock = false;
+        TurnTo(instruction.getHeading());
+    } else {
+        if (fp) {
+            hdg_lock = true;
+        }
+    }
+    if (instruction.getChangeAltitude()) {}
+
+}
+
+
+void FGAIAircraft::handleFirstWaypoint() {
+    bool eraseWaypoints;         //TODO YAGNI
+    if (trafficRef) {
+        eraseWaypoints = true;
+    } else {
+        eraseWaypoints = false;
+    }
+
+    FGAIFlightPlan::waypoint* prev = 0; // the one behind you
+    FGAIFlightPlan::waypoint* curr = 0; // the one ahead
+    FGAIFlightPlan::waypoint* next = 0;// the next plus 1
+
     spinCounter = 0;
     tempReg = "";
-    //prev_dist_to_go = HUGE;
-    //cerr << "Before increment " << curr-> name << endl;
-    fp->IncrementWaypoint(eraseWaypoints); 
-    //prev = fp->getPreviousWaypoint(); //first waypoint
-    //curr = fp->getCurrentWaypoint();  //second waypoint
-    //next = fp->getNextWaypoint();     //third waypoint (might not exist!) 
-    //cerr << "After increment " << prev-> name << endl;
+
+    //TODO fp should handle this
+    fp->IncrementWaypoint(eraseWaypoints);
     if (!(fp->getNextWaypoint()) && trafficRef)
-      {
-       loadNextLeg();
-      }
-    //cerr << "After load " << prev-> name << endl;
-    prev = fp->getPreviousWaypoint(); //first waypoint
-    curr = fp->getCurrentWaypoint();  //second waypoint
-    next = fp->getNextWaypoint();     //third waypoint (might not exist!) 
-    //cerr << "After load " << prev-> name << endl;
+        loadNextLeg();
+
+    prev = fp->getPreviousWaypoint();   //first waypoint
+    curr = fp->getCurrentWaypoint();    //second waypoint
+    next = fp->getNextWaypoint();       //third waypoint (might not exist!)
+
     setLatitude(prev->latitude);
     setLongitude(prev->longitude);
     setSpeed(prev->speed);
     setAltitude(prev->altitude);
+
     if (prev->speed > 0.0)
-      setHeading(fp->getBearing(prev->latitude, prev->longitude, curr));
+        setHeading(fp->getBearing(prev->latitude, prev->longitude, curr));
     else
-      {
-       setHeading(fp->getBearing(curr->latitude, curr->longitude, prev));
-      }
-    // If next doesn't exist, as in incrementally created flightplans for 
-    // AI/Trafficmanager created plans, 
+        setHeading(fp->getBearing(curr->latitude, curr->longitude, prev));
+
+    // If next doesn't exist, as in incrementally created flightplans for
+    // AI/Trafficmanager created plans,
     // Make sure lead distance is initialized otherwise
-    if (next) 
-      fp->setLeadDistance(speed, hdg, curr, next);
-    
-    if (curr->crossat > -1000.0) { //use a calculated descent/climb rate
-      use_perf_vs = false;
-      tgt_vs = (curr->crossat - prev->altitude)/
-       (fp->getDistanceToGo(pos.lat(), pos.lon(), curr)/
-        6076.0/prev->speed*60.0);
-        tgt_altitude = curr->crossat;
+    if (next)
+        fp->setLeadDistance(speed, hdg, curr, next);
+
+    if (curr->crossat > -1000.0) //use a calculated descent/climb rate
+    {
+        use_perf_vs = false;
+        tgt_vs = (curr->crossat - prev->altitude)
+                 / (fp->getDistanceToGo(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr)
+                    / 6076.0 / prev->speed*60.0);
+        tgt_altitude_ft = curr->crossat;
     } else {
-      use_perf_vs = true;
-      tgt_altitude = prev->altitude;
+        use_perf_vs = true;
+        tgt_altitude_ft = prev->altitude;
     }
     alt_lock = hdg_lock = true;
     no_roll = prev->on_ground;
-    if (no_roll)
-      {
-       Transform();         // make sure aip is initialized.
-       getGroundElev(60.1); // make sure it's exectuted first time around, so force a large dt value
-       //getGroundElev(60.1); // Need to do this twice.
-       //cerr << trafficRef->getRegistration() << " Setting altitude to " << tgt_altitude << endl;
-       setAltitude(tgt_altitude);
-      }
-    prevSpeed = 0;
-    //cout << "First waypoint:  " << prev->name << endl;
-    //cout << "  Target speed:    " << tgt_speed << endl;
-    //cout << "  Target altitude: " << tgt_altitude << endl;
-    //cout << "  Target heading:  " << tgt_heading << endl << endl;       
-    //cerr << "Done Flightplan init" << endl;
-    return;  
-  } // end of initialization
-  
-  // let's only process the flight plan every 100 ms.
-  if ((dt_count < 0.1) || (now < fp->getStartTime()))
-    {
-      //cerr  << "done fp dt" << endl;
-      return;
-    } else {
-      dt_count = 0;
+    if (no_roll) {
+        Transform();             // make sure aip is initialized.
+        getGroundElev(60.1);     // make sure it's executed first time around, so force a large dt value
+        doGroundAltitude();
     }
-  // check to see if we've reached the lead point for our next turn
-  double dist_to_go = fp->getDistanceToGo(pos.lat(), pos.lon(), curr);
-  
-  //cerr << "2" << endl;
-  double lead_dist = fp->getLeadDistance();
-  //cerr << " Distance : " << dist_to_go << ": Lead distance " << lead_dist << endl;
-  // experimental: Use fabs, because speed can be negative (I hope) during push_back.
-  if (lead_dist < fabs(2*speed)) 
-    {
-      lead_dist = fabs(2*speed);  //don't skip over the waypoint
+    // Make sure to announce the aircraft's position
+    announcePositionToController();
+    prevSpeed = 0;
+}
+
+
+/**
+ * Check Execution time (currently once every 100 ms)
+ * Add a bit of randomization to prevent the execution of all flight plans
+ * in synchrony, which can add significant periodic framerate flutter.
+ *
+ * @param now
+ * @return
+ */
+bool FGAIAircraft::fpExecutable(time_t now) {
+    double rand_exec_time = (rand() % 100) / 100;
+    return (dt_count > (0.1+rand_exec_time)) && (fp->isActive(now));
+}
+
+
+/**
+ * Check to see if we've reached the lead point for our next turn
+ *
+ * @param curr
+ * @return
+ */
+bool FGAIAircraft::leadPointReached(FGAIFlightPlan::waypoint* curr) {
+    double dist_to_go = fp->getDistanceToGo(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr);
+
+    //cerr << "2" << endl;
+    double lead_dist = fp->getLeadDistance();
+    //cerr << " Distance : " << dist_to_go << ": Lead distance " << lead_dist << endl;
+    // experimental: Use fabs, because speed can be negative (I hope) during push_back.
+
+    if (lead_dist < fabs(2*speed)) {
+      //don't skip over the waypoint
+      lead_dist = fabs(2*speed);
       //cerr << "Extending lead distance to " << lead_dist << endl;
-    } 
-//   FGAirport * apt = trafficRef->getDepartureAirport();
-//   if ((dist_to_go > prev_dist_to_go) && trafficRef && apt)
-//     {
-//       if (apt->getId() == string("EHAM"))
-//     cerr << "Alert: " << trafficRef->getRegistration() << " is moving away from waypoint " << curr->name  << endl
-//          << "Target heading : " << tgt_heading << "act heading " << hdg << " Tgt speed : " << tgt_speed << endl
-//          << "Lead distance : " << lead_dist  << endl
-//          << "Distance to go: " << dist_to_go << endl;
-      
-//     }
-  prev_dist_to_go = dist_to_go;
-  //cerr << "2" << endl;
-  //if (no_roll)
-  //  lead_dist = 10.0;
-  //cout << "Leg : " << (fp->getLeg()-1) << ". dist_to_go: " << dist_to_go << ",  lead_dist: " << lead_dist << ", tgt_speed " << tgt_speed << ", tgt_heading " << tgt_heading << " speed " << speed << " hdg " << hdg << ". Altitude "  << altitude << " TAget alt :" << tgt_altitude << endl;
-  
-  if ( dist_to_go < lead_dist ) {
-    //prev_dist_to_go = HUGE;
-    // For traffic manager generated aircraft: 
-    // check if the aircraft flies of of user range. And adjust the
-    // Current waypoint's elevation according to Terrain Elevation
-    if (curr->finished) {  //end of the flight plan
-      {
-       setDie(true);
-       //cerr << "Done die end of fp" << endl;
-      }
-      return;
     }
-    
-    // we've reached the lead-point for the waypoint ahead 
-    //cerr << "4" << endl;
-    //cerr << "Situation after lead point" << endl;
-    //cerr << "Prviious: " << prev->name << endl;
-    //cerr << "Current : " << curr->name << endl;
-    //cerr << "Next    : " << next->name << endl;
-    if (next) 
-      {
-       tgt_heading = fp->getBearing(curr, next);  
-       spinCounter = 0;
-      }
-    fp->IncrementWaypoint(eraseWaypoints);
-    if (!(fp->getNextWaypoint()) && trafficRef)
-      {
-       loadNextLeg();
-      }
-    prev = fp->getPreviousWaypoint();
-    curr = fp->getCurrentWaypoint();
-    next = fp->getNextWaypoint();
-    // Now that we have incremented the waypoints, excute some traffic manager specific code
-    // based on the name of the waypoint we just passed.
-    if (trafficRef)
-      {        
-       double userLatitude  = fgGetDouble("/position/latitude-deg");
-       double userLongitude = fgGetDouble("/position/longitude-deg");
-       double course, distance;
-       SGWayPoint current  (pos.lon(),
-                            pos.lat(),
-                            0);
-       SGWayPoint user (   userLongitude,
-                           userLatitude,
-                           0);
-       user.CourseAndDistance(current, &course, &distance);
-       if ((distance * SG_METER_TO_NM) > TRAFFICTOAIDIST)
-         {
-           setDie(true);
-           //cerr << "done fp die out of range" << endl;
-           return;
-         }
-       
-       FGAirport * dep = trafficRef->getDepartureAirport();
-       FGAirport * arr = trafficRef->getArrivalAirport();
-       // At parking the beginning of the airport
-       if (!( dep && arr))
-         {
-           setDie(true);
-           return;
-         }
-       //if ((dep->getId() == string("EHAM") || (arr->getId() == string("EHAM"))))
-       //  {
-       //      cerr << trafficRef->getRegistration() 
-       //           << " Enroute from " << dep->getId() 
-       //           << " to "           << arr->getId()
-       //           << " just crossed " << prev->name
-       //           << " Assigned rwy     " << fp->getRunwayId()
-       //           << " " << fp->getRunway() << endl;
-       // }
-       //if ((dep->getId() == string("EHAM")) && (prev->name == "park2"))
-       //  {
-       //    cerr << "Schiphol ground " 
-       //       << trafficRef->getCallSign();
-       //    if (trafficRef->getHeavy())
-       //      cerr << "Heavy";
-       //    cerr << ", is type " 
-       //       << trafficRef->getAircraft()
-       //       << " ready to go. IFR to "
-       //       << arr->getId() <<endl;
-       //  }   
-       if (prev->name == "park2")
-         dep->releaseParking(fp->getGate());
-       
-       //if ((arr->getId() == string("EHAM")) && (prev->name  == "Center"))
-       //  {
-       //    
-       //    cerr << "Schiphol ground " 
-       //       << trafficRef->getCallSign();
-       //    if (trafficRef->getHeavy())
-       //      cerr << "Heavy";
-       //    cerr << " landed runway " 
-       //       << fp->getRunway()
-       //       << " request taxi to gate " 
-       //       << arr->getParkingName(fp->getGate()) 
-       //       << endl;
-       //  }
-       if (prev->name == "END")
-         fp->setTime(trafficRef->getDepartureTime());
-       //cerr << "5" << endl;
-      }
-    if (next) 
-      {
-       //cerr << "Current waypoint" << curr->name << endl;
-       //cerr << "Next waypoint" << next->name << endl;
-       fp->setLeadDistance(speed, tgt_heading, curr, next);
-      }
-    //cerr << "5.1" << endl;
-    if (curr->crossat > -1000.0) {
-      //cerr << "5.1a" << endl;
-      use_perf_vs = false;
-      tgt_vs = (curr->crossat - altitude)/
-       (fp->getDistanceToGo(pos.lat(), pos.lon(), curr)/6076.0/speed*60.0);
-      //cerr << "5.1b" << endl;
-      tgt_altitude = curr->crossat;
-    } else {
-      //cerr << "5.1c" << endl;
-      use_perf_vs = true;
-      //cerr << "5.1d" << endl;        
-      tgt_altitude = prev->altitude;
-      //cerr << "Setting target altitude : " <<tgt_altitude << endl;
+
+    //prev_dist_to_go = dist_to_go;
+    return dist_to_go < lead_dist;
+}
+
+
+bool FGAIAircraft::aiTrafficVisible() {
+    double userLatitude  = fgGetDouble("/position/latitude-deg");
+    double userLongitude = fgGetDouble("/position/longitude-deg");
+    double course, distance;
+
+    SGWayPoint current(pos.getLongitudeDeg(), pos.getLatitudeDeg(), 0);
+    SGWayPoint user (userLongitude, userLatitude, 0);
+
+    user.CourseAndDistance(current, &course, &distance);
+
+    return ((distance * SG_METER_TO_NM) <= TRAFFICTOAIDIST);
+}
+
+
+/**
+ * Handle release of parking gate, once were taxiing. Also ensure service time at the gate
+ * in the case of an arrival.
+ *
+ * @param prev
+ * @return
+ */
+
+//TODO the trafficRef is the right place for the method
+bool FGAIAircraft::handleAirportEndPoints(FGAIFlightPlan::waypoint* prev, time_t now) {
+    // prepare routing from one airport to another
+    FGAirport * dep = trafficRef->getDepartureAirport();
+    FGAirport * arr = trafficRef->getArrivalAirport();
+
+    if (!( dep && arr))
+        return false;
+
+    // This waypoint marks the fact that the aircraft has passed the initial taxi
+    // departure waypoint, so it can release the parking.
+    if (prev->name == "park2") {
+        dep->getDynamics()->releaseParking(fp->getGate());
     }
-    //cerr << "6" << endl;
-    tgt_speed = prev->speed;
-    hdg_lock = alt_lock = true;
-    no_roll = prev->on_ground;
-    //cout << "Crossing waypoint: " << prev->name << endl;
-    //cout << "  Target speed:    " << tgt_speed << endl;
-    //cout << "  Target altitude: " << tgt_altitude << endl;
-    //cout << "  Target heading:  " << tgt_heading << endl << endl;       
-  } else {
-    
-    double calc_bearing = fp->getBearing(pos.lat(), pos.lon(), curr);
+
+    // This is the last taxi waypoint, and marks the the end of the flight plan
+    // so, the schedule should update and wait for the next departure time.
+    if (prev->name == "END") {
+        time_t nextDeparture = trafficRef->getDepartureTime();
+        // make sure to wait at least 20 minutes at parking to prevent "nervous" taxi behavior
+        if (nextDeparture < (now+1200)) {
+            nextDeparture = now + 1200;
+        }
+        fp->setTime(nextDeparture); // should be "next departure"
+    }
+
+    return true;
+}
+
+
+/**
+ * Check difference between target bearing and current heading and correct if necessary.
+ *
+ * @param curr
+ */
+void FGAIAircraft::controlHeading(FGAIFlightPlan::waypoint* curr) {
+    double calc_bearing = fp->getBearing(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr);
     //cerr << "Bearing = " << calc_bearing << endl;
-    if (speed < 0)
-      {
-       calc_bearing +=180;
-       if (calc_bearing > 360)
-         calc_bearing -= 360;
-      }
-    if (finite(calc_bearing))
-      {
-       double hdg_error = calc_bearing - tgt_heading;
-       if (fabs(hdg_error) > 1.0) {
-         TurnTo( calc_bearing ); 
-       }
-      }
-    else
-      {
-       cerr << "calc_bearing is not a finite number : "
-            << "Speed " << speed
-            << "pos : " << pos.lat() << ", " << pos.lon()
-            << "waypoint " << curr->latitude << ", " << curr->longitude << endl;
-       cerr << "waypoint name " << curr->name;
-       exit(1);
-      }
-    double speed_diff = speed - prevSpeed;
-    // Update the lead distance calculation if speed has changed sufficiently
-    // to prevent spinning (hopefully);
-    if (fabs(speed_diff) > 10)
-      { 
-       prevSpeed = speed;
-       fp->setLeadDistance(speed, tgt_heading, curr, next);
-      }
-    
-    //cerr << "Done Processing FlightPlan"<< endl;
-  } // if (dt count) else
-}
-
-  bool FGAIAircraft::_getGearDown() const {
-   return ((props->getFloatValue("position/altitude-agl-ft") < 900.0)
-            && (props->getFloatValue("velocities/airspeed-kt")
-                 < performance->land_speed*1.25));
-}
-
-
-void FGAIAircraft::loadNextLeg() 
-{
-  //delete fp;
-  //time_t now = time(NULL) + fgGetLong("/sim/time/warp");
-  
-  
-  //FGAIModelEntity entity;
-  //entity.m_class = "jet_transport";
-  //entity.path = modelPath.c_str();
-  //entity.flightplan = "none";
-  //entity.latitude = _getLatitude();
-  //entity.longitude = _getLongitude();
- //entity.altitude = trafficRef->getCruiseAlt() * 100; // convert from FL to feet
-  //entity.speed = 450; // HACK ALERT
-  //entity.fp = new FGAIFlightPlan(&entity, courseToDest, i->getDepartureTime(), dep, arr);
-  int leg;
-  if ((leg = fp->getLeg())  == 10)
-    {
-      trafficRef->next();
-      leg = 1;
-      fp->setLeg(leg);
-      
-      //cerr << "Resetting leg : " << leg << endl;
+    if (speed < 0) {
+        calc_bearing +=180;
+        if (calc_bearing > 360)
+            calc_bearing -= 360;
     }
-  //{
-  //leg++;
-  //fp->setLeg(leg);
-  //cerr << "Creating leg number : " << leg << endl;
-  FGAirport *dep = trafficRef->getDepartureAirport();
-  FGAirport *arr = trafficRef->getArrivalAirport();
-  if (!(dep && arr))
-    {
-      setDie(true);
-      //cerr << "Failed to get airport in AIAircraft::ProcessFlightplan()" << endl;
-      //if (dep)
-      //  cerr << "Departure " << dep->getId() << endl;
-      //if (arr) 
-      //  cerr << "Arrival   " << arr->getId() << endl;
+
+    if (finite(calc_bearing)) {
+        double hdg_error = calc_bearing - tgt_heading;
+        if (fabs(hdg_error) > 0.01) {
+            TurnTo( calc_bearing );
+        }
+
+    } else {
+        cerr << "calc_bearing is not a finite number : "
+        << "Speed " << speed
+        << "pos : " << pos.getLatitudeDeg() << ", " << pos.getLongitudeDeg()
+        << "waypoint " << curr->latitude << ", " << curr->longitude << endl;
+        cerr << "waypoint name " << curr->name;
+        exit(1);                 // FIXME
     }
-  else
+}
+
+
+/**
+ * Update the lead distance calculation if speed has changed sufficiently
+ * to prevent spinning (hopefully);
+ *
+ * @param curr
+ * @param next
+ */
+void FGAIAircraft::controlSpeed(FGAIFlightPlan::waypoint* curr, FGAIFlightPlan::waypoint* next) {
+    double speed_diff = speed - prevSpeed;
+
+    if (fabs(speed_diff) > 10) {
+        prevSpeed = speed;
+        if (next) {
+            fp->setLeadDistance(speed, tgt_heading, curr, next);
+        }
+    }
+}
+
+
+/**
+ * Update target values (heading, alt, speed) depending on flight plan or control properties
+ */
+void FGAIAircraft::updatePrimaryTargetValues() {
+    if (fp)                      // AI object has a flightplan
     {
-      double cruiseAlt = trafficRef->getCruiseAlt() * 100;
-      //cerr << "Creating new leg using " << cruiseAlt << " as cruise altitude."<< endl;
-      
-      fp->create (dep,
-                 arr,
-                 leg,
-                 cruiseAlt, //(trafficRef->getCruiseAlt() * 100), // convert from FL to feet
-                 trafficRef->getSpeed(),
-                 _getLatitude(),
-                 _getLongitude(),
-                 false,
-                 trafficRef->getRadius(),
-                 trafficRef->getFlightType(), 
-                 acType,
-                 company);
-      //prev = fp->getPreviousWaypoint();
-      //curr = fp->getCurrentWaypoint();
-      //next = fp->getNextWaypoint();
-      //cerr << "25" << endl;
-      //if (next) 
-      //       {
-      //  //cerr << "Next waypoint" << next->name << endl;
-      //         fp->setLeadDistance(speed, tgt_heading, curr, next);
-      //       }
-      //cerr << "25.1" << endl;
-      //if (curr->crossat > -1000.0) {
-      //       //cerr << "25.1a" << endl;
-      //       use_perf_vs = false;
-      //       
-      //       tgt_vs = (curr->crossat - altitude)/
-      //         (fp->getDistanceToGo(pos.lat(), pos.lon(), curr)/6076.0/speed*60.0);
-      //       //cerr << "25.1b" << endl;
-      //       tgt_altitude = curr->crossat;
-      //} else {
-      //       //cerr << "25.1c" << endl;
-      //       use_perf_vs = true;
-      //       //cerr << "25.1d" << endl;      
-      //       tgt_altitude = prev->altitude;
-      //       //cerr << "Setting target altitude : " <<tgt_altitude << endl;
-      // }
-      //cerr << "26" << endl;
-      //tgt_speed = prev->speed;
-      //hdg_lock = alt_lock = true;
-      //no_roll = prev->on_ground;
-      
+        //TODO make this a function of AIBase
+        time_t now = time(NULL) + fgGetLong("/sim/time/warp");
+        //cerr << "UpateTArgetValues() " << endl;
+        ProcessFlightPlan(dt, now);
+
+        // Do execute Ground elev for inactive aircraft, so they
+        // Are repositioned to the correct ground altitude when the user flies within visibility range.
+        // In addition, check whether we are out of user range, so this aircraft
+        // can be deleted.
+        if (onGround()) {
+                Transform();     // make sure aip is initialized.
+                getGroundElev(dt);
+                doGroundAltitude();
+                // Transform();
+                pos.setElevationFt(altitude_ft);
+        }
+        if (trafficRef) {
+           //cerr << trafficRef->getRegistration() << " Setting altitude to " << altitude_ft;
+            if (! aiTrafficVisible()) {
+                setDie(true);
+                //cerr << trafficRef->getRegistration() << " is set to die " << endl;
+                throw AI_OutOfSight();
+            }
+        }
+        if (! fp->isActive(now)) { 
+            throw FP_Inactive();
+        }
+    } else {
+        // no flight plan, update target heading, speed, and altitude
+        // from control properties.  These default to the initial
+        // settings in the config file, but can be changed "on the
+        // fly".
+        string lat_mode = props->getStringValue("controls/flight/lateral-mode");
+        if ( lat_mode == "roll" ) {
+            double angle
+            = props->getDoubleValue("controls/flight/target-roll" );
+            RollTo( angle );
+        } else {
+            double angle
+            = props->getDoubleValue("controls/flight/target-hdg" );
+            TurnTo( angle );
+        }
+
+        string lon_mode
+        = props->getStringValue("controls/flight/longitude-mode");
+        if ( lon_mode == "alt" ) {
+            double alt = props->getDoubleValue("controls/flight/target-alt" );
+            ClimbTo( alt );
+        } else {
+            double angle
+            = props->getDoubleValue("controls/flight/target-pitch" );
+            PitchTo( angle );
+        }
+
+        AccelTo( props->getDoubleValue("controls/flight/target-spd" ) );
     }
-  //}
-  //else
-  //{
-  //delete entity.fp;
-  //entity.fp = new FGAIFlightPlan(&entity, 
-  //                            999,  // A hack
-  //                            trafficRef->getDepartureTime(), 
-  //                            trafficRef->getDepartureAirport(), 
-  //                            trafficRef->getArrivalAirport(),
-  //                            false,
-  //                            acType,
-  //                            company);
-  //SetFlightPlan(entity.fp);
 }
 
+void FGAIAircraft::updatePosition() {
+    // convert speed to degrees per second
+    double speed_north_deg_sec = cos( hdg * SGD_DEGREES_TO_RADIANS )
+                                 * speed * 1.686 / ft_per_deg_lat;
+    double speed_east_deg_sec  = sin( hdg * SGD_DEGREES_TO_RADIANS )
+                                 * speed * 1.686 / ft_per_deg_lon;
 
+    // set new position
+    pos.setLatitudeDeg( pos.getLatitudeDeg() + speed_north_deg_sec * dt);
+    pos.setLongitudeDeg( pos.getLongitudeDeg() + speed_east_deg_sec * dt);
+}
 
-// Note: This code is copied from David Luff's AILocalTraffic 
-// Warning - ground elev determination is CPU intensive
-// Either this function or the logic of how often it is called
-// will almost certainly change.
 
-void FGAIAircraft::getGroundElev(double dt) {
-  dt_elev_count += dt;
-  //return;
-  if (dt_elev_count < (10.0 + (rand() % 100))) // Update minimally every 10 secs, but add some randomness to prevent them all IA objects doing this synced
-    {
-      return;
+void FGAIAircraft::updateHeading() {
+    // adjust heading based on current bank angle
+    if (roll == 0.0)
+        roll = 0.01;
+
+    if (roll != 0.0) {
+        // double turnConstant;
+        //if (no_roll)
+        //  turnConstant = 0.0088362;
+        //else
+        //  turnConstant = 0.088362;
+        // If on ground, calculate heading change directly
+        if (onGround()) {
+            double headingDiff = fabs(hdg-tgt_heading);
+
+            if (headingDiff > 180)
+                headingDiff = fabs(headingDiff - 360);
+
+            groundTargetSpeed = tgt_speed - (tgt_speed * (headingDiff/45));
+            if (sign(groundTargetSpeed) != sign(tgt_speed))
+                groundTargetSpeed = 0.21 * sign(tgt_speed); // to prevent speed getting stuck in 'negative' mode
+
+            if (headingDiff > 30.0) {
+                // invert if pushed backward
+                headingChangeRate += dt * sign(roll);
+
+                if (headingChangeRate > 30)
+                    headingChangeRate = 30;
+                else if (headingChangeRate < -30)
+                    headingChangeRate = -30;
+
+            } else {
+                if (fabs(headingChangeRate) > headingDiff)
+                    headingChangeRate = headingDiff*sign(roll);
+                else
+                    headingChangeRate += dt * sign(roll);
+            }
+            hdg += headingChangeRate * dt;
+        } else {
+            if (fabs(speed) > 1.0) {
+                turn_radius_ft = 0.088362 * speed * speed
+                                 / tan( fabs(roll) / SG_RADIANS_TO_DEGREES );
+            } else {
+                // Check if turn_radius_ft == 0; this might lead to a division by 0.
+                turn_radius_ft = 1.0;
+            }
+            double turn_circum_ft = SGD_2PI * turn_radius_ft;
+            double dist_covered_ft = speed * 1.686 * dt;
+            double alpha = dist_covered_ft / turn_circum_ft * 360.0;
+            hdg += alpha * sign(roll);
+        }
+        while ( hdg > 360.0 ) {
+            hdg -= 360.0;
+            spinCounter++;
+        }
+        while ( hdg < 0.0) {
+            hdg += 360.0;
+            spinCounter--;
+        }
     }
-  else
-    {
-      dt_elev_count = 0;
+}
+
+
+void FGAIAircraft::updateBankAngleTarget() {
+    // adjust target bank angle if heading lock engaged
+    if (hdg_lock) {
+        double bank_sense = 0.0;
+        double diff = fabs(hdg - tgt_heading);
+        if (diff > 180)
+            diff = fabs(diff - 360);
+
+        double sum = hdg + diff;
+        if (sum > 360.0)
+            sum -= 360.0;
+        if (fabs(sum - tgt_heading) < 1.0) {
+            bank_sense = 1.0;    // right turn
+        } else {
+            bank_sense = -1.0;   // left turn
+        }
+        if (diff < _performance->maximumBankAngle()) {
+            tgt_roll = diff * bank_sense;
+        } else {
+            tgt_roll = _performance->maximumBankAngle() * bank_sense;
+        }
+        if ((fabs((double) spinCounter) > 1) && (diff > _performance->maximumBankAngle())) {
+            tgt_speed *= 0.999;  // Ugly hack: If aircraft get stuck, they will continually spin around.
+            // The only way to resolve this is to make them slow down.
+        }
     }
-  // It would be nice if we could set the correct tile center here in order to get a correct
-  // answer with one call to the function, but what I tried in the two commented-out lines
-  // below only intermittently worked, and I haven't quite groked why yet.
-  //SGBucket buck(pos.lon(), pos.lat());
-  //aip.getSGLocation()->set_tile_center(Point3D(buck.get_center_lon(), buck.get_center_lat(), 0.0));
-  
-  // Only do the proper hitlist stuff if we are within visible range of the viewer.
-  double visibility_meters = fgGetDouble("/environment/visibility-m"); 
-
-  FGViewer* vw = globals->get_current_view();
-  double 
-    course, 
-    distance;
-
-  //Point3D currView(vw->getLongitude_deg(), 
-  //              vw->getLatitude_deg(), 0.0);
-  SGWayPoint current  (pos.lon(),
-                      pos.lat(),
-                      0);
-  SGWayPoint view (   vw->getLongitude_deg(),
-                     vw->getLatitude_deg(),
-                     0);
-  view.CourseAndDistance(current, &course, &distance);
-  if(distance > visibility_meters) {
-    //aip.getSGLocation()->set_cur_elev_m(aptElev);
-    return;
-  }
+}
+
+
+void FGAIAircraft::updateVerticalSpeedTarget() {
+    // adjust target Altitude, based on ground elevation when on ground
+    if (onGround()) {
+        getGroundElev(dt);
+        doGroundAltitude();
+    } else if (alt_lock) {
+        // find target vertical speed
+        if (use_perf_vs) {
+            if (altitude_ft < tgt_altitude_ft) {
+                tgt_vs = tgt_altitude_ft - altitude_ft;
+                if (tgt_vs > _performance->climbRate())
+                    tgt_vs = _performance->climbRate();
+            } else {
+                tgt_vs = tgt_altitude_ft - altitude_ft;
+                if (tgt_vs  < (-_performance->descentRate()))
+                    tgt_vs = -_performance->descentRate();
+            }
+        } else {
+            double max_vs = 4*(tgt_altitude_ft - altitude_ft);
+            double min_vs = 100;
+            if (tgt_altitude_ft < altitude_ft)
+                min_vs = -100.0;
+            if ((fabs(tgt_altitude_ft - altitude_ft) < 1500.0)
+                    && (fabs(max_vs) < fabs(tgt_vs)))
+                tgt_vs = max_vs;
+
+            if (fabs(tgt_vs) < fabs(min_vs))
+                tgt_vs = min_vs;
+        }
+    } //else 
+    //    tgt_vs = 0.0;
+}
+
+void FGAIAircraft::updatePitchAngleTarget() {
+    // if on ground and above vRotate -> initial rotation
+    if (onGround() && (speed > _performance->vRotate()))
+        tgt_pitch = 8.0; // some rough B737 value 
+
+    //TODO pitch angle on approach and landing
     
-  
-  //globals->get_tile_mgr()->prep_ssg_nodes( acmodel_location,
-  globals->get_tile_mgr()->prep_ssg_nodes( aip.getSGLocation(),        visibility_meters );
-  Point3D scenery_center = globals->get_scenery()->get_center();
-
-  globals->get_tile_mgr()->update( aip.getSGLocation(), 
-                                  visibility_meters, 
-                                  (aip.getSGLocation())->get_absolute_view_pos( scenery_center ) );
-  // save results of update in SGLocation for fdm...
-  
-  //if ( globals->get_scenery()->get_cur_elev() > -9990 ) {
-  //   acmodel_location->
-  //   set_cur_elev_m( globals->get_scenery()->get_cur_elev() );
-  //}
-  
-  // The need for this here means that at least 2 consecutive passes are needed :-(
-  aip.getSGLocation()->set_tile_center( globals->get_scenery()->get_next_center() );
-    globals->get_tile_mgr()->prep_ssg_nodes( aip.getSGLocation(),      visibility_meters );
-    //Point3D scenery_center = globals->get_scenery()->get_center();
-
-  globals->get_tile_mgr()->update( aip.getSGLocation(), 
-                                  visibility_meters, 
-                                  (aip.getSGLocation())->get_absolute_view_pos( scenery_center ) );
-  // save results of update in SGLocation for fdm...
-  
-  //if ( globals->get_scenery()->get_cur_elev() > -9990 ) {
-  //   acmodel_location->
-  //   set_cur_elev_m( globals->get_scenery()->get_cur_elev() );
-  //}
-  
-  // The need for this here means that at least 2 consecutive passes are needed :-(
-  aip.getSGLocation()->set_tile_center( globals->get_scenery()->get_next_center() );
-  //cerr << "Transform Elev is " << globals->get_scenery()->get_cur_elev() << '\n';
-  tgt_altitude = (globals->get_scenery()->get_cur_elev() * SG_METER_TO_FEET) + groundOffset;
-}
-
-//globals->get_tile_mgr()->prep_ssg_nodes( _aip.getSGLocation(),       visibility_meters );
-//Point3D scenery_center = globals->get_scenery()->get_center();
-//globals->get_tile_mgr()->update(_aip.getSGLocation(), visibility_meters, (_aip.getSGLocation())->get_absolute_view_pos( scenery_center ) );
-// save results of update in SGLocation for fdm...
-
-//if ( globals->get_scenery()->get_cur_elev() > -9990 ) {
-//     acmodel_location->
-//     set_cur_elev_m( globals->get_scenery()->get_cur_elev() );
-//}
-
-// The need for this here means that at least 2 consecutive passes are needed :-(
-//_aip.getSGLocation()->set_tile_center( globals->get_scenery()->get_next_center() );
-
-//cout << "Transform Elev is " << globals->get_scenery()->get_cur_elev() << '\n';
-//_aip.getSGLocation()->set_cur_elev_m(globals->get_scenery()->get_cur_elev());
-//return(globals->get_scenery()->get_cur_elev());
-//}
+    // match pitch angle to vertical speed
+    else if (tgt_vs > 0) {
+        tgt_pitch = tgt_vs * 0.005;
+    } else {
+        tgt_pitch = tgt_vs * 0.002;
+    }
+}
+
+void FGAIAircraft::handleATCRequests() {
+    //TODO implement NullController for having no ATC to save the conditionals
+    if (controller) {
+        controller->update(getID(),
+                           pos.getLatitudeDeg(),
+                           pos.getLongitudeDeg(),
+                           hdg,
+                           speed,
+                           altitude_ft, dt);
+        processATC(controller->getInstruction(getID()));
+    }
+}
+
+void FGAIAircraft::updateActualState() {
+    //update current state
+    //TODO have a single tgt_speed and check speed limit on ground on setting tgt_speed
+    updatePosition();
+
+    if (onGround())
+        speed = _performance->actualSpeed(this, groundTargetSpeed, dt);
+    else
+        speed = _performance->actualSpeed(this, tgt_speed, dt);
+
+    updateHeading();
+    roll = _performance->actualBankAngle(this, tgt_roll, dt);
+
+    // adjust altitude (meters) based on current vertical speed (fpm)
+    altitude_ft += vs / 60.0 * dt;
+    pos.setElevationFt(altitude_ft);
+
+    vs = _performance->actualVerticalSpeed(this, tgt_vs, dt);
+    pitch = _performance->actualPitch(this, tgt_pitch, dt);
+}
+
+void FGAIAircraft::updateSecondaryTargetValues() {
+    // derived target state values
+    updateBankAngleTarget();
+    updateVerticalSpeedTarget();
+    updatePitchAngleTarget();
+
+    //TODO calculate wind correction angle (tgt_yaw)
+}