Initial stab at making the AI plane take the user into account when flying a circuit. The AI plane will now delay it's turns to the various legs if the user has flown a wider pattern that it normally would in front of it. However, this is very much still work in progress - when the pattern gets extended the AI plane lands short of the runway, and it doesn't alter its speed around the circuit at all, only the turn positions. Still, its a start...

src/ATC/AILocalTraffic.cxx

@@ -605,6 +605,8 @@ void FGAILocalTraffic::FlyTrafficPattern(double dt) {
 	double wind_from = wind_from_hdg->getDoubleValue();
 	double wind_speed = wind_speed_knots->getDoubleValue();
 
+	double dveldt;
+	
 	switch(leg) {
 	case TAKEOFF_ROLL:
 		//inAir = false;
@@ -627,10 +629,27 @@ void FGAILocalTraffic::FlyTrafficPattern(double dt) {
 		break;
 	case CLIMBOUT:
 		track = rwy.hdg;
+		// Turn to crosswind if above 600ft AND if other traffic allows
+		// (decided in FGTower and accessed through GetCrosswindConstraint(...)).
 		if((pos.elev() - rwy.threshold_pos.elev()) * SG_METER_TO_FEET > 600) {
+			double cc = 0.0;
+			if(tower->GetCrosswindConstraint(cc)) {
+				if(orthopos.y() > cc) {
 					cout << "Turning to crosswind, distance from threshold = " << orthopos.y() << '\n'; 
 					leg = TURN1;
 				}
+			} else {
+				cout << "Turning to crosswind, distance from threshold = " << orthopos.y() << '\n'; 
+				leg = TURN1;
+			}
+		}
+		// Need to check for levelling off in case we can't turn crosswind as soon
+		// as we would like due to other traffic.
+		if((pos.elev() - rwy.threshold_pos.elev()) * SG_METER_TO_FEET > 1000) {
+			slope = 0.0;
+			pitch = 0.0;
+			IAS = 80.0;		// FIXME - use smooth transistion to new speed and attitude.
+		}
 		break;
 	case TURN1:
 		track += (360.0 / turn_time) * dt * patternDirection;
@@ -647,10 +666,19 @@ void FGAILocalTraffic::FlyTrafficPattern(double dt) {
 			pitch = 0.0;
 			IAS = 80.0;		// FIXME - use smooth transistion to new speed
 		}
-		// turn 1000m out for now
+		// turn 1000m out for now, taking other traffic into accout
 		if(fabs(orthopos.x()) > 980) {
+			double dd = 0.0;
+			if(tower->GetDownwindConstraint(dd)) {
+				if(fabs(orthopos.x()) > fabs(dd)) {
+					cout << "Turning to downwind, distance from centerline = " << fabs(orthopos.x()) << '\n'; 
 					leg = TURN2;
 				}
+			} else {
+				cout << "Turning to downwind, distance from centerline = " << fabs(orthopos.x()) << '\n'; 
+				leg = TURN2;
+			}
+		}
 		break;
 	case TURN2:
 		track += (360.0 / turn_time) * dt * patternDirection;
@@ -681,16 +709,27 @@ void FGAILocalTraffic::FlyTrafficPattern(double dt) {
 			transmitted = true;
 		}
 		if(orthopos.y() < -480) {
+			// FIXME - TODO - take tower baseleg constraint ie. other traffic, into account when calculating start of descent
 			slope = -4.0;	// FIXME - calculate to descent at 500fpm and hit the threshold (taking wind into account as well!!)
 			pitch = -3.0;
 			IAS = 85.0;
 		}
 		if(orthopos.y() < -980) {
-			//roll = -20;
+			double bb = 0.0;
+			if(tower->GetDownwindConstraint(bb)) {
+				if(fabs(orthopos.y()) > fabs(bb)) {
+					cout << "Turning to base, distance from threshold = " << fabs(orthopos.y()) << '\n'; 
 					leg = TURN3;
 					transmitted = false;
 					IAS = 80.0;
 				}
+			} else {
+				cout << "Turning to base, distance from threshold = " << fabs(orthopos.y()) << '\n'; 
+				leg = TURN3;
+				transmitted = false;
+				IAS = 80.0;
+			}
+		}
 		break;
 	case TURN3:
 		track += (360.0 / turn_time) * dt * patternDirection;
@@ -759,7 +798,7 @@ void FGAILocalTraffic::FlyTrafficPattern(double dt) {
 			pos.setelev(aip.getSGLocation()->get_cur_elev_m() + wheelOffset);
 		}
 		track = rwy.hdg;
-		double dveldt = -5.0;
+		dveldt = -5.0;
 		vel += dveldt * dt;
 		// FIXME - differentiate between touch and go and full stops
 		if(vel <= 15.0) {
@@ -775,6 +814,8 @@ void FGAILocalTraffic::FlyTrafficPattern(double dt) {
 			}
 		}
 		break;
+	case LEG_UNKNOWN:
+		break;
     }
 
 	if(inAir) {

src/ATC/tower.cxx

@@ -44,6 +44,7 @@ longFinalAcknowledged(false),
 finalReported(false),
 finalAcknowledged(false),
 opType(TTT_UNKNOWN),
+leg(LEG_UNKNOWN),
 isUser(false)
 {
 	plane.callsign = "UNKNOWN";
@@ -59,6 +60,7 @@ longFinalAcknowledged(false),
 finalReported(false),
 finalAcknowledged(false),
 opType(TTT_UNKNOWN),
+leg(LEG_UNKNOWN),
 isUser(false)
 {
 	plane = p;
@@ -74,6 +76,7 @@ longFinalAcknowledged(false),
 finalReported(false),
 finalAcknowledged(false),
 opType(TTT_UNKNOWN),
+leg(LEG_UNKNOWN),
 isUser(false)
 {
 	plane.callsign = "UNKNOWN";
@@ -90,6 +93,7 @@ longFinalAcknowledged(false),
 finalReported(false),
 finalAcknowledged(false),
 opType(TTT_UNKNOWN),
+leg(LEG_UNKNOWN),
 isUser(false)
 {
 	plane = p;
@@ -230,7 +234,6 @@ void FGTower::Update(double dt) {
 	// Do one plane from the hold list
 	if(ii == 4) {
 		if(holdList.size()) {
-			//cout << "A" << endl;
 			//cout << "*holdListItr = " << *holdListItr << endl;
 			if(holdListItr == holdList.end()) {
 				holdListItr = holdList.begin();
@@ -240,14 +243,10 @@ void FGTower::Update(double dt) {
 			TowerPlaneRec* t = *holdListItr;
 			//cout << "t = " << t << endl;
 			if(t->holdShortReported) {
-				//cout << "B" << endl;
 				double responseTime = 10.0;		// seconds - this should get more sophisticated at some point
 				if(t->clearanceCounter > responseTime) {
-					//cout << "C" << endl;
 					if(t->nextOnRwy) {
-						//cout << "D" << endl;
 						if(rwyOccupied) {
-							//cout << "E" << endl;
 							// Do nothing for now - consider acknowloging hold short eventually
 						} else {
 							// Lets Roll !!!!
@@ -337,20 +336,49 @@ void FGTower::Update(double dt) {
 		if(circuitList.size()) {
 			circuitListItr = circuitList.begin();	// TODO - at the moment we're constraining plane 2 based on plane 1 - this won't work for 3 planes in the circuit!!
 			TowerPlaneRec* t = *circuitListItr;
+			if(t->isUser) {
+				t->pos.setlon(user_lon_node->getDoubleValue());
+				t->pos.setlat(user_lat_node->getDoubleValue());
+				t->pos.setelev(user_elev_node->getDoubleValue());
+			} else {
+				// TODO - set/update the position if it's an AI plane
+			}
 			Point3D tortho = ortho.ConvertToLocal(t->pos);
 			if(t->isUser) {
 				// Need to figure out which leg he's on
+				//cout << "rwy.hdg = " << rwy.hdg << " user hdg = " << user_hdg_node->getDoubleValue();
 				double ho = GetAngleDiff_deg(user_hdg_node->getDoubleValue(), rwy.hdg);
+				//cout << " ho = " << ho << '\n';
 				// TODO FIXME - get the wind and convert this to track, or otherwise use track somehow!!!
 				// If it's gusty might need to filter the value, although we are leaving 30 degrees each way leeway!
 				if(abs(ho) < 30) {
 					// could be either takeoff, climbout or landing - check orthopos.y
-					if((tortho.y() < 0) || (t->leg == TURN4) || (t->leg == LANDING_ROLL)) {
+					//cout << "tortho.y = " << tortho.y() << '\n';
-						t->leg = LANDING_ROLL;
+					if((tortho.y() < 0) || (t->leg == TURN4) || (t->leg == FINAL)) {
-						//cout << "Landing_roll\n";
+						t->leg = FINAL;
+						//cout << "Final\n";
 					} else {
 						t->leg = CLIMBOUT;	// TODO - check elev wrt. apt elev to differentiate takeoff roll and climbout
 						//cout << "Climbout\n";
+						// If it's the user we may be unsure of his/her intentions.
+						// (Hopefully the AI planes won't try confusing the sim!!!)
+						if(t->opType == TTT_UNKNOWN) {
+							if(tortho.y() > 5000) {
+								// 5 km out from threshold - assume it's a departure
+								t->opType = OUTBOUND;
+								// Since we are unknown operation we should be in depList already.
+								circuitList.erase(circuitListItr);
+								circuitListItr = circuitList.begin();
+							}
+						} else if(t->opType == CIRCUIT) {
+							if(tortho.y() > 10000) {
+								// 10 km out - assume the user has abandoned the circuit!!
+								t->opType = OUTBOUND;
+								depList.push_back(t);
+								circuitList.erase(circuitListItr);
+								circuitListItr = circuitList.begin();
+							}
+						}
 					}
 				} else if(abs(ho) < 60) {
 					// turn1 or turn 4
@@ -394,29 +422,35 @@ void FGTower::Update(double dt) {
 			case FINAL:
 				// Base leg must be at least as far out as the plane is - actually possibly not necessary for separation, but we'll use that for now.
 				base_leg_pos = tortho.y();
+				//cout << "base_leg_pos = " << base_leg_pos << '\n';
 				break;
 			case TURN4:
 				// Fall through to base
 			case BASE:
 				base_leg_pos = tortho.y();
+				//cout << "base_leg_pos = " << base_leg_pos << '\n';
 				break;
 			case TURN3:
 				// Fall through to downwind
 			case DOWNWIND:
 				// Only have the downwind leg pos as turn-to-base constraint if more negative than we already have.
 				base_leg_pos = (tortho.y() < base_leg_pos ? tortho.y() : base_leg_pos);
+				//cout << "base_leg_pos = " << base_leg_pos;
 				downwind_leg_pos = tortho.x();		// Assume that a following plane can simply be constrained by the immediately in front downwind plane
+				//cout << " downwind_leg_pos = " << downwind_leg_pos << '\n';
 				break;
 			case TURN2:
 				// Fall through to crosswind
 			case CROSSWIND:
 				crosswind_leg_pos = tortho.y();
+				//cout << "crosswind_leg_pos = " << crosswind_leg_pos << '\n';
 				break;
 			case TURN1:
 				// Fall through to climbout
 			case CLIMBOUT:
 				// Only use current by constraint as largest
-				crosswind_leg_pos = (tortho.y() > crosswind_leg_pos ? tortho.x() : crosswind_leg_pos);
+				crosswind_leg_pos = (tortho.y() > crosswind_leg_pos ? tortho.y() : crosswind_leg_pos);
+				//cout << "crosswind_leg_pos = " << crosswind_leg_pos << '\n';
 				break;
 			case TAKEOFF_ROLL:
 				break;
@@ -452,6 +486,37 @@ void FGTower::Update(double dt) {
 }
 
 
+// Returns true if positions of crosswind/downwind/base leg turns should be constrained by previous traffic
+// plus the constraint position as a rwy orientated orthopos (meters)
+bool FGTower::GetCrosswindConstraint(double& cpos) {
+	if(crosswind_leg_pos != 0.0) {
+		cpos = crosswind_leg_pos;
+		return(true);
+	} else {
+		cpos = 0.0;
+		return(false);
+	}
+}
+bool FGTower::GetDownwindConstraint(double& dpos) {
+	if(downwind_leg_pos != 0.0) {
+		dpos = downwind_leg_pos;
+		return(true);
+	} else {
+		dpos = 0.0;
+		return(false);
+	}
+}
+bool FGTower::GetBaseConstraint(double& bpos) {
+	if(base_leg_pos != 0.0) {
+		bpos = base_leg_pos;
+		return(true);
+	} else {
+		bpos = 0.0;
+		return(false);
+	}
+}
+
+
 // Figure out which runways are active.
 // For now we'll just be simple and do one active runway - eventually this will get much more complex
 // This is a private function - public interface to the results of this is through GetActiveRunway

src/ATC/tower.hxx

@@ -136,6 +136,12 @@ public:
 	
 	inline FGGround* GetGroundPtr() { return ground; }
 	
+	// Returns true if positions of crosswind/downwind/base leg turns should be constrained by previous traffic
+	// plus the constraint position as a rwy orientated orthopos (meters)
+	bool GetCrosswindConstraint(double& cpos);
+	bool GetDownwindConstraint(double& dpos);
+	bool GetBaseConstraint(double& bpos);
+
 private:
 	FGATCMgr* ATCmgr;	
 	// This is purely for synactic convienience to avoid writing globals->get_ATC_mgr()-> all through the code!