1 // FGAIBallistic - FGAIBase-derived class creates a ballistic object
3 // Written by David Culp, started November 2003.
4 // - davidculp2@comcast.net
6 // This program is free software; you can redistribute it and/or
7 // modify it under the terms of the GNU General Public License as
8 // published by the Free Software Foundation; either version 2 of the
9 // License, or (at your option) any later version.
11 // This program is distributed in the hope that it will be useful, but
12 // WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 // General Public License for more details.
16 // You should have received a copy of the GNU General Public License
17 // along with this program; if not, write to the Free Software
18 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include <simgear/math/point3d.hxx>
27 #include "AIBallistic.hxx"
30 FGAIBallistic::FGAIBallistic(FGAIManager* mgr) {
32 _type_str = "ballistic";
40 FGAIBallistic::~FGAIBallistic() {
44 bool FGAIBallistic::init() {
46 aero_stabilized = true;
53 void FGAIBallistic::bind() {
55 props->tie("sim/time/elapsed-sec",
56 SGRawValueMethods<FGAIBallistic,double>(*this,
57 &FGAIBallistic::_getTime));
60 void FGAIBallistic::unbind() {
61 // FGAIBase::unbind();
62 props->untie("sim/time/elapsed-sec");
65 void FGAIBallistic::update(double dt) {
72 void FGAIBallistic::setAzimuth(double az) {
77 void FGAIBallistic::setElevation(double el) {
78 pitch = elevation = el;
82 void FGAIBallistic::setStabilization(bool val) {
83 aero_stabilized = val;
86 void FGAIBallistic::setDragArea(double a) {
90 void FGAIBallistic::setLife(double seconds) {
94 void FGAIBallistic::setBuoyancy(double fpss) {
98 void FGAIBallistic::setWind_from_east(double fps) {
102 void FGAIBallistic::setWind_from_north(double fps) {
103 wind_from_north = fps;
106 void FGAIBallistic::setWind(bool val) {
109 void FGAIBallistic::Run(double dt) {
112 if (life_timer > life) setDie(true);
114 double speed_north_deg_sec;
115 double speed_east_deg_sec;
116 double wind_speed_from_north_deg_sec;
117 double wind_speed_from_east_deg_sec;
119 // the two drag calculations below assume sea-level density,
120 // mass of 0.03 slugs, drag coeff of 0.295
121 // adjust speed due to drag
122 speed -= 0.0116918 * drag_area * speed * speed * dt;
123 if ( speed < 0.0 ) speed = 0.0;
124 vs = sin( pitch * SG_DEGREES_TO_RADIANS ) * speed;
125 hs = cos( pitch * SG_DEGREES_TO_RADIANS ) * speed;
127 // convert horizontal speed (fps) to degrees per second
128 speed_north_deg_sec = cos(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lat;
129 speed_east_deg_sec = sin(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lon;
131 // convert wind speed (fps) to degrees per second
138 wind_speed_from_north_deg_sec = wind_from_north / ft_per_deg_lat;
139 wind_speed_from_east_deg_sec = wind_from_east / ft_per_deg_lon;
143 // pos.setlat( pos.lat() + (speed_north_deg_sec * dt) );
144 // pos.setlon( pos.lon() + (speed_east_deg_sec * dt) );
149 pos.setlat( pos.lat() + (speed_north_deg_sec - wind_speed_from_north_deg_sec) * dt );
150 pos.setlon( pos.lon() + (speed_east_deg_sec - wind_speed_from_east_deg_sec) * dt );
152 // adjust vertical speed for acceleration of gravity
153 vs -= (gravity - buoyancy) * dt;
155 // adjust altitude (feet)
157 pos.setelev(altitude * SG_FEET_TO_METER);
159 // recalculate pitch (velocity vector) if aerostabilized
160 if (aero_stabilized) pitch = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
162 // recalculate total speed
163 speed = sqrt( vs * vs + hs * hs);
165 // set destruction flag if altitude less than sea level -1000
166 if (altitude < -1000.0) setDie(true);
170 double FGAIBallistic::_getTime() const {