+ //calculate velocity due to external force
+ double force_speed_north_deg_sec = 0;
+ double force_speed_east_deg_sec = 0;
+// double vs_force_fps = 0;
+ double hs_force_fps = 0;
+ double v_force_acc_fpss = 0;
+ double force_speed_north_fps = 0;
+ double force_speed_east_fps = 0;
+ double h_force_lbs = 0;
+ double normal_force_lbs = 0;
+ double normal_force_fpss = 0;
+ double static_friction_force_lbs = 0;
+ double dynamic_friction_force_lbs = 0;
+ double friction_force_speed_north_fps = 0;
+ double friction_force_speed_east_fps = 0;
+ double friction_force_speed_north_deg_sec = 0;
+ double friction_force_speed_east_deg_sec = 0;
+ double force_elevation_deg = 0;
+
+ if (_external_force) {
+ SGPropertyNode *n = fgGetNode(_force_path.c_str(), true);
+ double force_lbs = n->getChild("force-lb", 0, true)->getDoubleValue();
+ force_elevation_deg = n->getChild("force-elevation-deg", 0, true)->getDoubleValue();
+ double force_azimuth_deg = n->getChild("force-azimuth-deg", 0, true)->getDoubleValue();
+
+ //resolve force into vertical and horizontal components:
+ double v_force_lbs = force_lbs * sin( force_elevation_deg * SG_DEGREES_TO_RADIANS );
+ h_force_lbs = force_lbs * cos( force_elevation_deg * SG_DEGREES_TO_RADIANS );
+
+ //ground interaction
+
+ if (getHtAGL()){
+ double deadzone = 0.1;
+
+ if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
+ normal_force_lbs = (_mass * slugs_to_lbs) - v_force_lbs;
+
+ if ( normal_force_lbs < 0 )
+ normal_force_lbs = 0;
+
+ pos.setElevationFt(0 + _ground_offset);
+ if (vs < 0)
+ vs = -vs * 0.5;
+
+ // calculate friction
+ // we assume a static Coefficient of Friction (mu) of 0.62 (wood on concrete)
+ double mu = 0.62;
+
+ static_friction_force_lbs = mu * normal_force_lbs * _frictionFactor;
+
+ //adjust horizontal force. We assume that a speed of <= 5 fps is static
+ if (h_force_lbs <= static_friction_force_lbs && hs <= 5){
+ h_force_lbs = hs = 0;
+ speed_north_fps = speed_east_fps = 0;
+ } else
+ dynamic_friction_force_lbs = (static_friction_force_lbs * 0.95);
+
+ //ignore wind when on the ground for now
+ //TODO fix this
+ _wind_from_north = 0;
+ _wind_from_east = 0;
+
+ }
+
+ }
+
+ //acceleration = (force(lbsf)/mass(slugs))
+ v_force_acc_fpss = v_force_lbs/_mass;
+ normal_force_fpss = normal_force_lbs/_mass;
+ double h_force_acc_fpss = h_force_lbs/_mass;
+ double dynamic_friction_acc_fpss = dynamic_friction_force_lbs/_mass;
+
+ // velocity = acceleration * dt
+ hs_force_fps = h_force_acc_fpss * dt;
+ double friction_force_fps = dynamic_friction_acc_fpss * dt;
+
+ //resolve horizontal speeds into north and east components:
+ force_speed_north_fps = cos(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
+ force_speed_east_fps = sin(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
+
+ friction_force_speed_north_fps = cos(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
+ friction_force_speed_east_fps = sin(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
+
+ // convert horizontal speed (fps) to degrees per second
+ force_speed_north_deg_sec = force_speed_north_fps / ft_per_deg_lat;
+ force_speed_east_deg_sec = force_speed_east_fps / ft_per_deg_lon;
+
+ friction_force_speed_north_deg_sec = friction_force_speed_north_fps / ft_per_deg_lat;
+ friction_force_speed_east_deg_sec = friction_force_speed_east_fps / ft_per_deg_lon;
+ }
+
+ // convert wind speed (fps) to degrees lat/lon per second
+ double wind_speed_from_north_deg_sec = _wind_from_north / ft_per_deg_lat;
+ double wind_speed_from_east_deg_sec = _wind_from_east / ft_per_deg_lon;
+
+ //recombine the horizontal velocity components
+ hs = sqrt(((speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps)
+ * (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
+ + ((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)
+ * (speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)));
+
+ if (hs <= 0.00001)
+ hs = 0;
+
+ // adjust vertical speed for acceleration of gravity, buoyancy, and vertical force
+ vs -= (_gravity - _buoyancy - v_force_acc_fpss - normal_force_fpss) * dt;
+
+ if (vs <= 0.00001 && vs >= -0.00001)
+ vs = 0;
+
+ // set new position
+ if(_slave_load_to_ac) {
+ setHitchPos();
+ pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
+ pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
+ pos.setElevationFt(hitchpos.getElevationFt());
+
+ if (getHtAGL()){
+ double deadzone = 0.1;
+
+ if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
+ pos.setElevationFt(0 + _ground_offset);
+ } else {
+ pos.setElevationFt(hitchpos.getElevationFt() + _load_offset);
+ }
+
+ }
+ } else {
+ pos.setLatitudeDeg( pos.getLatitudeDeg()
+ + (speed_north_deg_sec - wind_speed_from_north_deg_sec
+ + force_speed_north_deg_sec + friction_force_speed_north_deg_sec) * dt );
+ pos.setLongitudeDeg( pos.getLongitudeDeg()
+ + (speed_east_deg_sec - wind_speed_from_east_deg_sec
+ + force_speed_east_deg_sec + friction_force_speed_east_deg_sec) * dt );
+ pos.setElevationFt(pos.getElevationFt() + vs * dt);
+ }
+
+ // recalculate total speed
+ if ( vs == 0 && hs == 0)
+ speed = 0;
+ else
+ speed = sqrt( vs * vs + hs * hs) / SG_KT_TO_FPS;
+
+ // recalculate elevation and azimuth (velocity vectors)
+ _elevation = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
+ _azimuth = atan2((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps),
+ (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
+ * SG_RADIANS_TO_DEGREES;
+
+ // rationalise azimuth
+ if (_azimuth < 0)
+ _azimuth += 360;
+
+ if (_aero_stabilised) { // we simulate rotational moment of inertia by using a filter
+ const double coeff = 0.9;
+
+ // we assume a symetrical MI about the pitch and yaw axis
+ setPch(_elevation, dt, coeff);
+ setHdg(_azimuth, dt, coeff);
+ } else if (_force_stabilised) { // we simulate rotational moment of inertia by using a filter
+ const double coeff = 0.9;
+ double ratio = h_force_lbs/(_mass * slugs_to_lbs);
+
+ if (ratio > 1) ratio = 1;
+ if (ratio < -1) ratio = -1;
+
+ double force_pitch = acos(ratio) * SG_RADIANS_TO_DEGREES;
+
+ if (force_pitch <= force_elevation_deg)
+ force_pitch = force_elevation_deg;
+
+ // we assume a symetrical MI about the pitch and yaw axis
+ setPch(force_pitch,dt, coeff);
+ setHdg(_azimuth, dt, coeff);
+ }
+
+ //do impacts and collisions
+ if (_report_impact && !_impact_reported)
+ handle_impact();
+
+ if (_report_collision && !_collision_reported)
+ handle_collision();
+
+ // set destruction flag if altitude less than sea level -1000
+ if (altitude_ft < -1000.0 && life != -1)
+ setDie(true);
+
+} // end Run
+
+double FGAIBallistic::_getTime() const {
+ return _life_timer;
+}
+
+void FGAIBallistic::handle_impact() {
+
+ // try terrain intersection
+ if(!getHtAGL())
+ return;
+
+ if (_ht_agl_ft <= 0) {
+ SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: terrain impact");
+ report_impact(_elevation_m);
+ _impact_reported = true;
+
+ if (life == -1){
+ invisible = true;
+ } else if (_subID == 0) // kill the AIObject if there is no subsubmodel
+ setDie(true);
+ }
+}
+
+void FGAIBallistic::handle_collision()
+{
+ const FGAIBase *object = manager->calcCollision(pos.getElevationFt(),
+ pos.getLatitudeDeg(),pos.getLongitudeDeg(), _fuse_range);
+
+ if (object) {
+ SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: object hit");
+ report_impact(pos.getElevationM(), object);
+ _collision_reported = true;
+ }
+}
+
+void FGAIBallistic::report_impact(double elevation, const FGAIBase *object)
+{
+ _impact_lat = pos.getLatitudeDeg();
+ _impact_lon = pos.getLongitudeDeg();
+ _impact_elev = elevation;
+ _impact_speed = speed * SG_KT_TO_MPS;
+ _impact_hdg = hdg;
+ _impact_pitch = pitch;
+ _impact_roll = roll;
+
+ SGPropertyNode *n = props->getNode("impact", true);
+ if (object)
+ n->setStringValue("type", object->getTypeString());
+ else
+ n->setStringValue("type", "terrain");
+
+ n->setDoubleValue("longitude-deg", _impact_lon);
+ n->setDoubleValue("latitude-deg", _impact_lat);
+ n->setDoubleValue("elevation-m", _impact_elev);
+ n->setDoubleValue("heading-deg", _impact_hdg);
+ n->setDoubleValue("pitch-deg", _impact_pitch);
+ n->setDoubleValue("roll-deg", _impact_roll);
+ n->setDoubleValue("speed-mps", _impact_speed);
+
+ _impact_report_node->setStringValue(props->getPath());
+}
+
+SGVec3d FGAIBallistic::getCartUserPos() const {
+ SGVec3d cartUserPos = SGVec3d::fromGeod(userpos);
+ return cartUserPos;
+}
+
+SGVec3d FGAIBallistic::getCartHitchPos() const{
+
+ // convert geodetic positions to geocentered
+ SGVec3d cartuserPos = getCartUserPos();
+ SGVec3d cartPos = getCartPos();
+
+ // Transform to the right coordinate frame, configuration is done in
+ // the x-forward, y-right, z-up coordinates (feet), computation
+ // in the simulation usual body x-forward, y-right, z-down coordinates
+ // (meters) )
+ SGVec3d _off(_x_offset * SG_FEET_TO_METER,
+ _y_offset * SG_FEET_TO_METER,
+ -_z_offset * SG_FEET_TO_METER);
+
+ // Transform the user position to the horizontal local coordinate system.
+ SGQuatd hlTrans = SGQuatd::fromLonLat(userpos);
+
+ // and postrotate the orientation of the user model wrt the horizontal
+ // local frame
+ hlTrans *= SGQuatd::fromYawPitchRollDeg(
+ manager->get_user_heading(),
+ manager->get_user_pitch(),
+ manager->get_user_roll());
+
+ // The offset converted to the usual body fixed coordinate system
+ // rotated to the earth-fixed coordinates axis
+ SGVec3d off = hlTrans.backTransform(_off);
+
+ // Add the position offset of the user model to get the geocentered position
+ SGVec3d offsetPos = cartuserPos + off;
+
+ return offsetPos;
+}
+
+void FGAIBallistic::setHitchPos(){
+ // convert the hitch geocentered position to geodetic
+ SGVec3d carthitchPos = getCartHitchPos();
+
+ SGGeodesy::SGCartToGeod(carthitchPos, hitchpos);
+}
+
+double FGAIBallistic::getDistanceLoadToHitch() const {
+ //calculate the distance load to hitch
+ SGVec3d carthitchPos = getCartHitchPos();
+ SGVec3d cartPos = getCartPos();
+
+ SGVec3d diff = carthitchPos - cartPos;
+ double distance = norm(diff);
+ return distance * SG_METER_TO_FEET;
+}
+
+void FGAIBallistic::setHitchVelocity(double dt) {
+ //calculate the distance from the previous hitch position
+ SGVec3d carthitchPos = getCartHitchPos();
+ SGVec3d diff = carthitchPos - _oldcarthitchPos;
+
+ double distance = norm(diff);
+
+ //calculate speed knots
+ speed = (distance/dt) * SG_MPS_TO_KT;
+
+ //now calulate the angle between the old and current hitch positions (degrees)
+ double angle = 0;
+ double daltM = hitchpos.getElevationM() - oldhitchpos.getElevationM();
+
+ if (fabs(distance) < SGLimits<float>::min()) {
+ angle = 0;
+ } else {
+ double sAngle = daltM/distance;
+ sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
+ angle = SGMiscd::rad2deg(asin(sAngle));
+ }
+
+ _elevation = angle;
+
+ //calculate the bearing of the new hitch position from the old
+ double az1, az2, dist;
+
+ geo_inverse_wgs_84(oldhitchpos, hitchpos, &az1, &az2, &dist);
+
+ _azimuth = az1;
+
+ // and finally store the new values
+ _oldcarthitchPos = carthitchPos;
+ oldhitchpos = hitchpos;
+}
+
+double FGAIBallistic::getElevLoadToHitch() const {
+ // now the angle, positive angles are upwards
+ double distance = getDistanceLoadToHitch() * SG_FEET_TO_METER;
+ double angle = 0;
+ double daltM = hitchpos.getElevationM() - pos.getElevationM();
+
+ if (fabs(distance) < SGLimits<float>::min()) {
+ angle = 0;
+ } else {
+ double sAngle = daltM/distance;
+ sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
+ angle = SGMiscd::rad2deg(asin(sAngle));
+ }
+
+ return angle;
+}
+
+double FGAIBallistic::getBearingLoadToHitch() const {
+ //calculate the bearing and range of the second pos from the first
+ double az1, az2, distance;
+
+ geo_inverse_wgs_84(pos, hitchpos, &az1, &az2, &distance);
+
+ return az1;
+}
+
+double FGAIBallistic::getRelBrgHitchToUser() const {
+ //calculate the relative bearing
+ double az1, az2, distance;
+
+ geo_inverse_wgs_84(hitchpos, userpos, &az1, &az2, &distance);
+
+ double rel_brg = az1 - hdg;
+
+ if (rel_brg > 180)
+ rel_brg -= 360;
+
+ return rel_brg;
+}
+
+double FGAIBallistic::getElevHitchToUser() const {
+
+ //calculate the distance from the user position
+ SGVec3d carthitchPos = getCartHitchPos();
+ SGVec3d cartuserPos = getCartUserPos();
+
+ SGVec3d diff = cartuserPos - carthitchPos;
+
+ double distance = norm(diff);
+ double angle = 0;
+
+ double daltM = userpos.getElevationM() - hitchpos.getElevationM();
+
+ // now the angle, positive angles are upwards
+ if (fabs(distance) < SGLimits<float>::min()) {
+ angle = 0;
+ } else {
+ double sAngle = daltM/distance;
+ sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
+ angle = SGMiscd::rad2deg(asin(sAngle));
+ }
+
+ return angle;