fix a segmentation fault situation that is exposed at least on IRIX (but not Linux).

[flightgear.git] / src / AIModel / AIBallistic.cxx

diff --git a/src/AIModel/AIBallistic.cxx b/src/AIModel/AIBallistic.cxx
index b6675ff05eb740c5db6c571af00328e36747b13d..d3ea25a1be4828b187902b1b96105e3f3e666923 100644 (file)
--- a/src/AIModel/AIBallistic.cxx
+++ b/src/AIModel/AIBallistic.cxx
@@ -27,12 +27,16 @@
 #include "AIBallistic.hxx"
 
 
+
 FGAIBallistic::FGAIBallistic(FGAIManager* mgr) {
     manager = mgr;
     _type_str = "ballistic";
     _otype = otBallistic;
     drag_area = 0.007;
     life_timer = 0.0;
+    gravity = 32;
+//  buoyancy = 64;
+    no_roll = false;
 }
 
 FGAIBallistic::~FGAIBallistic() {
@@ -41,15 +45,19 @@ FGAIBallistic::~FGAIBallistic() {
 
 bool FGAIBallistic::init() {
    FGAIBase::init();
-   aero_stabilized =  true;
+   aero_stabilized = true;
    hdg = azimuth;
    pitch = elevation;
+   roll = rotation;
+   Transform();
    return true;
 }
 
 void FGAIBallistic::bind() {
 //    FGAIBase::bind();
-   props->tie("sim/time/elapsed-sec", SGRawValuePointer<double>(&life_timer));
+   props->tie("sim/time/elapsed-sec",
+               SGRawValueMethods<FGAIBallistic,double>(*this,
+                                          &FGAIBallistic::_getTime));
 }
 
 void FGAIBallistic::unbind() {
@@ -73,6 +81,9 @@ void FGAIBallistic::setElevation(double el) {
    pitch = elevation = el;
 }
 
+void FGAIBallistic::setRoll(double rl) {
+   rotation = rl;
+}
 
 void FGAIBallistic::setStabilization(bool val) {
    aero_stabilized = val;
@@ -86,37 +97,82 @@ void FGAIBallistic::setLife(double seconds) {
    life = seconds;
 }
 
-void FGAIBallistic::Run(double dt) {
+void FGAIBallistic::setBuoyancy(double fpss) {
+   buoyancy = fpss;
+}
+
+void FGAIBallistic::setWind_from_east(double fps) {
+   wind_from_east = fps;
+}
+
+void FGAIBallistic::setWind_from_north(double fps) {
+   wind_from_north = fps;
+}
+
+void FGAIBallistic::setWind(bool val) {
+   wind = val;
+}
+
+void FGAIBallistic::setCd(double c) {
+   Cd = c;
+}
+
+void FGAIBallistic::setWeight(double w) {
+   weight = w;
+}
 
+void FGAIBallistic::Run(double dt) {
    life_timer += dt;
    if (life_timer > life) setDie(true); 
 
    double speed_north_deg_sec;
    double speed_east_deg_sec;
-
-   // the two drag calculations below assume sea-level density, 
-   // mass of 0.03 slugs,  drag coeff of 0.295
-   // adjust speed due to drag 
-   speed -= 0.0116918 * drag_area * speed * speed * dt;
+   double wind_speed_from_north_deg_sec;
+   double wind_speed_from_east_deg_sec;
+   double mass;
+      
+   // the drag calculations below assume sea-level density,
+   // rho = 0.023780  slugs/ft3
+   // calculate mass
+   mass = weight * lbs_to_slugs;
+   
+   // drag = Cd * 0.5 * rho * speed * speed * drag_area;
+   // acceleration = drag/mass;
+   // adjust speed by drag
+   speed -= (Cd * 0.5 * rho * speed * speed * drag_area/mass) * dt; 
+
+   // don't let speed become negative
    if ( speed < 0.0 ) speed = 0.0;
+   
+   // calculate vertical and horizontal speed components
    vs = sin( pitch * SG_DEGREES_TO_RADIANS ) * speed;
    hs = cos( pitch * SG_DEGREES_TO_RADIANS ) * speed;
 
    // convert horizontal speed (fps) to degrees per second
    speed_north_deg_sec = cos(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lat;
    speed_east_deg_sec  = sin(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lon;
-
+   
+   // if wind not required, set to zero
+   if (!wind){
+      wind_from_north = 0;
+      wind_from_east = 0;
+   }
+  
+   // convert wind speed (fps) to degrees per second
+   wind_speed_from_north_deg_sec = wind_from_north / ft_per_deg_lat;
+   wind_speed_from_east_deg_sec  = wind_from_east / 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); 
+   pos.setlat( pos.lat() + (speed_north_deg_sec - wind_speed_from_north_deg_sec) * dt );
+   pos.setlon( pos.lon() + (speed_east_deg_sec - wind_speed_from_east_deg_sec) * dt ); 
 
+   // adjust vertical speed for acceleration of gravity and buoyancy
+   vs -= (gravity - buoyancy) * dt;
+   
    // adjust altitude (feet)
    altitude += vs * dt;
    pos.setelev(altitude * SG_FEET_TO_METER); 
 
-   // adjust vertical speed for acceleration of gravity
-   vs -= 32.17 * dt;
-
    // recalculate pitch (velocity vector) if aerostabilized
    if (aero_stabilized) pitch = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
 
@@ -126,5 +182,10 @@ void FGAIBallistic::Run(double dt) {
    // set destruction flag if altitude less than sea level -1000
    if (altitude < -1000.0) setDie(true);
 
+}  // end Run
+
+double FGAIBallistic::_getTime() const {
+   return life_timer;
 }
 
+// end AIBallistic