submodel: Add random error for azimuth and elevation

Signed-off-by: onox <denkpadje@gmail.com>

diff --git a/src/AIModel/AIBallistic.cxx b/src/AIModel/AIBallistic.cxx
index d0868bef6c8866284ed84c1388395019d180c8fe..78ed4cdf0a479809ff6eddb3ac44ebf13ac78241 100644 (file)
--- a/src/AIModel/AIBallistic.cxx
+++ b/src/AIModel/AIBallistic.cxx
@@ -48,14 +48,17 @@ _ht_agl_ft(0.0),
 _azimuth(0.0),
 _elevation(0.0),
 _rotation(0.0),
+_az_random_error(0.0),
+_el_random_error(0.0),
 hs(0),
 _elapsed_time(0),
 _aero_stabilised(false),
 _drag_area(0.007),
 _cd(0.029),
+_init_cd(0.029),
 _cd_randomness(0.0),
-_life_timer(0.0),
 _buoyancy(0),
+_life_timer(0.0),
 _wind(true),
 _mass(0),
 _random(false),
@@ -274,13 +277,24 @@ void FGAIBallistic::update(double dt)
 
 void FGAIBallistic::setAzimuth(double az) {
     if (_random)
-        hdg = _azimuth = (az - 5 ) + (10 * sg_random());
+        hdg = _azimuth = az - _az_random_error + 2 * _az_random_error * sg_random();
     else 
         hdg = _azimuth = az;
 }
 
+void FGAIBallistic::setAzimuthRandomError(double error) {
+    _az_random_error = error;
+}
+
+void FGAIBallistic::setElevationRandomError(double error) {
+    _el_random_error = error;
+}
+
 void FGAIBallistic::setElevation(double el) {
-    pitch = _elevation = el;
+    if (_random)
+        pitch = _elevation = el - _el_random_error + 2 * _el_random_error * sg_random();
+    else
+        pitch = _elevation = el;
 }
 
 void FGAIBallistic::setRoll(double rl) {
@@ -328,6 +342,7 @@ void FGAIBallistic::setWind(bool val) {
 
 void FGAIBallistic::setCd(double cd) {
     _cd = cd;
+    _init_cd = cd;
 }
 
 void FGAIBallistic::setCdRandomness(double randomness) {
@@ -664,23 +679,28 @@ void FGAIBallistic::Run(double dt) {
     // Set the contents in the appropriate tank or other property in the parent to zero
     setContents(0);
 
-    // Randomize Cd by +- a certain percentage of the ideal Cd
-    double Cd;
-    if (_random)
-        Cd = _cd * (1 - _cd_randomness + 2 * _cd_randomness * sg_random());
-    else
-        Cd = _cd;
+    if (_random) {
+        // Keep the new Cd within +- 10% of the current Cd to avoid a fluctuating value
+        double cd_min = _cd * 0.9;
+        double cd_max = _cd * 1.1;
+
+        // Randomize Cd by +- a certain percentage of the initial Cd
+        _cd = _init_cd * (1 - _cd_randomness + 2 * _cd_randomness * sg_random());
+
+        if (_cd < cd_min) _cd = cd_min;
+        if (_cd > cd_max) _cd = cd_max;
+    }
 
     // Adjust Cd by Mach number. The equations are based on curves
     // for a conventional shell/bullet (no boat-tail).
     double Cdm;
 
     if (Mach < 0.7)
-        Cdm = 0.0125 * Mach + Cd;
+        Cdm = 0.0125 * Mach + _cd;
     else if (Mach < 1.2)
-        Cdm = 0.3742 * pow(Mach, 2) - 0.252 * Mach + 0.0021 + Cd;
+        Cdm = 0.3742 * pow(Mach, 2) - 0.252 * Mach + 0.0021 + _cd;
     else
-        Cdm = 0.2965 * pow(Mach, -1.1506) + Cd;
+        Cdm = 0.2965 * pow(Mach, -1.1506) + _cd;
 
     //cout <<_name << " Mach " << Mach << " Cdm " << Cdm 
     //    << " ballistic speed kts "<< speed <<  endl;

diff --git a/src/AIModel/AIBallistic.hxx b/src/AIModel/AIBallistic.hxx
index 01f08f87c1e373649ffc2e57d938a4bce6b02f37..5b18a88eaaefb3fa21960e23ab3339b059b97049 100644 (file)
--- a/src/AIModel/AIBallistic.hxx
+++ b/src/AIModel/AIBallistic.hxx
@@ -51,6 +51,8 @@ public:
 
     void setAzimuth( double az );
     void setElevation( double el );
+    void setAzimuthRandomError(double error);
+    void setElevationRandomError(double error);
     void setRoll( double rl );
     void setStabilisation( bool val );
     void setDragArea( double a );
@@ -169,11 +171,14 @@ public:
 
 private:
 
+    double _az_random_error; // maximum azimuth error in degrees
+    double _el_random_error; // maximum elevation error in degrees
     bool   _aero_stabilised; // if true, object will align with trajectory
     double _drag_area;       // equivalent drag area in ft2
     double _buoyancy;        // fps^2
     bool   _wind;            // if true, local wind will be applied to object
-    double _cd;              // drag coefficient
+    double _cd;              // current drag coefficient
+    double _init_cd;         // initial drag coefficient
     double _cd_randomness;   // randomness of Cd. 1.0 means +- 100%, 0.0 means no randomness
     double _life_timer;      // seconds
     double _mass;            // slugs

diff --git a/src/AIModel/submodel.cxx b/src/AIModel/submodel.cxx
index 4e58fcb0cca18f7974ca59205b1d193d81b96526..cb07fd80417c7684db53387e8cc8429194b99699 100644 (file)
--- a/src/AIModel/submodel.cxx
+++ b/src/AIModel/submodel.cxx
@@ -259,11 +259,13 @@ bool FGSubmodelMgr::release(submodel *sm, double dt)
     ballist->setName(sm->name);
     ballist->setSlaved(sm->slaved);
     ballist->setRandom(sm->random);
-    ballist->setLifeRandomness(sm->randomness);
+    ballist->setLifeRandomness(sm->life_randomness->get_value());
     ballist->setLatitude(offsetpos.getLatitudeDeg());
     ballist->setLongitude(offsetpos.getLongitudeDeg());
     ballist->setAltitude(offsetpos.getElevationFt());
+    ballist->setAzimuthRandomError(sm->azimuth_error->get_value());
     ballist->setAzimuth(IC.azimuth);
+    ballist->setElevationRandomError(sm->elevation_error->get_value());
     ballist->setElevation(IC.elevation);
     ballist->setRoll(IC.roll);
     ballist->setSpeed(IC.speed / SG_KT_TO_FPS);
@@ -274,6 +276,7 @@ bool FGSubmodelMgr::release(submodel *sm, double dt)
     ballist->setLife(sm->life);
     ballist->setBuoyancy(sm->buoyancy);
     ballist->setWind(sm->wind);
+    ballist->setCdRandomness(sm->cd_randomness->get_value());
     ballist->setCd(sm->cd);
     ballist->setStabilisation(sm->aero_stabilised);
     ballist->setNoRoll(sm->no_roll);
@@ -415,7 +418,6 @@ void FGSubmodelMgr::transform(submodel *sm)
     cosRz = cos(IC.azimuth * SG_DEGREES_TO_RADIANS);
     sinRz = sin(IC.azimuth * SG_DEGREES_TO_RADIANS);
 
-
     // Get submodel initial velocity vector angles in XZ and XY planes.
     // This vector should be added to aircraft's vector.
     IC.elevation += (yaw_offset * sinRx) + (pitch_offset * cosRx);
@@ -550,16 +552,43 @@ void FGSubmodelMgr::setData(int id, const string& path, bool serviceable, const
         sm->ext_force        = entry_node->getBoolValue("external-force", false);
         sm->force_path       = entry_node->getStringValue("force-path", "");
         sm->random           = entry_node->getBoolValue("random", false);
-        sm->randomness       = entry_node->getDoubleValue("randomness", 0.5);
 
         SGPropertyNode_ptr prop_root = fgGetNode("/", true);
         SGPropertyNode n;
 
         SGPropertyNode_ptr a = entry_node->getNode("yaw-offset");
-        sm->yaw_offset   = new FGXMLAutopilot::InputValue(*prop_root, a ? *a : n );
+        sm->yaw_offset   = new FGXMLAutopilot::InputValue(*prop_root, a ? *a : n);
 
         a = entry_node->getNode("pitch-offset");
-        sm->pitch_offset = new FGXMLAutopilot::InputValue(*prop_root, a ? *a : n );
+        sm->pitch_offset = new FGXMLAutopilot::InputValue(*prop_root, a ? *a : n);
+
+        // Randomness
+        a = entry_node->getNode("randomness", true);
+        SGPropertyNode_ptr b;
+
+        // Maximum azimuth randomness error in degrees
+        b = a->getNode("azimuth");
+        sm->azimuth_error   = new FGXMLAutopilot::InputValue(*prop_root, b ? *b : n);
+
+        // Maximum elevation randomness error in degrees
+        b = a->getNode("elevation");
+        sm->elevation_error = new FGXMLAutopilot::InputValue(*prop_root, b ? *b : n);
+
+        // Randomness of Cd (plus or minus)
+        b = a->getNode("cd");
+        if (!b) {
+            b = a->getNode("cd", true);
+            b->setDoubleValue(0.1);
+        }
+        sm->cd_randomness   = new FGXMLAutopilot::InputValue(*prop_root, *b);
+
+        // Randomness of life (plus or minus)
+        b = a->getNode("life");
+        if (!b) {
+            b = a->getNode("life", true);
+            b->setDoubleValue(0.5);
+        }
+        sm->life_randomness = new FGXMLAutopilot::InputValue(*prop_root, *b);
 
         if (sm->contents_node != 0)
             sm->contents = sm->contents_node->getDoubleValue();

diff --git a/src/AIModel/submodel.hxx b/src/AIModel/submodel.hxx
index 881e08d0bc418ab2517386684312662a47ced969..4c080526ef30c36e76459065e959f8f061079367 100644 (file)
--- a/src/AIModel/submodel.hxx
+++ b/src/AIModel/submodel.hxx
@@ -51,7 +51,10 @@ public:
         double             drag_area;
         double             life;
         double             buoyancy;
-        double             randomness;
+        FGXMLAutopilot::InputValue_ptr azimuth_error;
+        FGXMLAutopilot::InputValue_ptr elevation_error;
+        FGXMLAutopilot::InputValue_ptr cd_randomness;
+        FGXMLAutopilot::InputValue_ptr life_randomness;
         bool               wind;
         bool               first_time;
         double             cd;