1 // FGAIBallistic - FGAIBase-derived class creates a ballistic object
3 // Written by David Culp, started November 2003.
4 // - davidculp2@comcast.net
6 // With major additions by Mathias Froehlich & Vivian Meazza 2004-2007
8 // This program is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU General Public License as
10 // published by the Free Software Foundation; either version 2 of the
11 // License, or (at your option) any later version.
13 // This program is distributed in the hope that it will be useful, but
14 // WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
26 #include <simgear/math/point3d.hxx>
27 #include <simgear/math/sg_random.h>
28 #include <simgear/scene/material/mat.hxx>
32 #include <Scenery/scenery.hxx>
34 #include "AIBallistic.hxx"
38 const double FGAIBallistic::slugs_to_kgs = 14.5939029372;
40 FGAIBallistic::FGAIBallistic() :
41 FGAIBase(otBallistic),
42 _aero_stabilised(false),
51 _impact_report_node(0),
62 FGAIBallistic::~FGAIBallistic() {
65 void FGAIBallistic::readFromScenario(SGPropertyNode* scFileNode) {
69 FGAIBase::readFromScenario(scFileNode);
71 setAzimuth(scFileNode->getDoubleValue("azimuth", 0.0));
72 setElevation(scFileNode->getDoubleValue("elevation", 0.0));
73 setDragArea(scFileNode->getDoubleValue("eda", 0.007));
74 setLife(scFileNode->getDoubleValue("life", 900.0));
75 setBuoyancy(scFileNode->getDoubleValue("buoyancy", 0));
76 setWind_from_east(scFileNode->getDoubleValue("wind_from_east", 0));
77 setWind_from_north(scFileNode->getDoubleValue("wind_from_north", 0));
78 setWind(scFileNode->getBoolValue("wind", false));
79 setRoll(scFileNode->getDoubleValue("roll", 0.0));
80 setCd(scFileNode->getDoubleValue("cd", 0.029));
81 setMass(scFileNode->getDoubleValue("mass", 0.007));
82 setStabilisation(scFileNode->getBoolValue("aero_stabilized", false));
83 setNoRoll(scFileNode->getBoolValue("no-roll", false));
84 setRandom(scFileNode->getBoolValue("random", false));
85 setImpact(scFileNode->getBoolValue("impact", false));
86 setImpactReportNode(scFileNode->getStringValue("impact-reports"));
87 setName(scFileNode->getStringValue("name", "Bomb"));
90 bool FGAIBallistic::init(bool search_in_AI_path) {
91 FGAIBase::init(search_in_AI_path);
93 props->setStringValue("material/name", _mat_name.c_str());
94 props->setStringValue("name", _name.c_str());
96 // start with high value so that animations don't trigger yet
97 _ht_agl_ft = 10000000;
105 void FGAIBallistic::bind() {
107 props->tie("sim/time/elapsed-sec",
108 SGRawValueMethods<FGAIBallistic,double>(*this,
109 &FGAIBallistic::_getTime));
110 props->tie("material/load-resistance",
111 SGRawValuePointer<double>(&_load_resistance));
112 props->tie("material/solid",
113 SGRawValuePointer<bool>(&_solid));
114 props->tie("altitude-agl-ft",
115 SGRawValuePointer<double>(&_ht_agl_ft));
116 props->tie("impact/latitude-deg",
117 SGRawValuePointer<double>(&_impact_lat));
118 props->tie("impact/longitude-deg",
119 SGRawValuePointer<double>(&_impact_lon));
120 props->tie("impact/elevation-m",
121 SGRawValuePointer<double>(&_impact_elev));
122 props->tie("impact/speed-mps",
123 SGRawValuePointer<double>(&_impact_speed));
124 props->tie("impact/energy-kJ",
125 SGRawValuePointer<double>(&_impact_energy));
128 void FGAIBallistic::unbind() {
129 // FGAIBase::unbind();
130 props->untie("sim/time/elapsed-sec");
131 props->untie("material/load-resistance");
132 props->untie("material/solid");
133 props->untie("altitude-agl-ft");
134 props->untie("impact/latitude-deg");
135 props->untie("impact/longitude-deg");
136 props->untie("impact/elevation-m");
137 props->untie("impact/speed-mps");
138 props->untie("impact/energy-kJ");
141 void FGAIBallistic::update(double dt) {
142 FGAIBase::update(dt);
147 void FGAIBallistic::setAzimuth(double az) {
151 void FGAIBallistic::setElevation(double el) {
152 pitch = _elevation = el;
155 void FGAIBallistic::setRoll(double rl) {
159 void FGAIBallistic::setStabilisation(bool val) {
160 _aero_stabilised = val;
163 void FGAIBallistic::setNoRoll(bool nr) {
167 void FGAIBallistic::setDragArea(double a) {
171 void FGAIBallistic::setLife(double seconds) {
175 void FGAIBallistic::setBuoyancy(double fpss) {
179 void FGAIBallistic::setWind_from_east(double fps) {
180 _wind_from_east = fps;
183 void FGAIBallistic::setWind_from_north(double fps) {
184 _wind_from_north = fps;
187 void FGAIBallistic::setWind(bool val) {
191 void FGAIBallistic::setCd(double c) {
195 void FGAIBallistic::setMass(double m) {
199 void FGAIBallistic::setRandom(bool r) {
203 void FGAIBallistic::setImpact(bool i) {
207 void FGAIBallistic::setImpactReportNode(const string& path) {
209 _impact_report_node = 0;
211 _impact_report_node = fgGetNode(path.c_str(), true);
214 void FGAIBallistic::setName(const string& n) {
218 void FGAIBallistic::Run(double dt) {
220 // cout << "life timer 1" << _life_timer << dt << endl;
221 if (_life_timer > life)
224 double speed_north_deg_sec;
225 double speed_east_deg_sec;
226 double wind_speed_from_north_deg_sec;
227 double wind_speed_from_east_deg_sec;
228 double Cdm; // Cd adjusted by Mach Number
230 //randomise Cd by +- 5%
232 _Cd = _Cd * 0.95 + (0.05 * sg_random());
234 // Adjust Cd by Mach number. The equations are based on curves
235 // for a conventional shell/bullet (no boat-tail).
237 Cdm = 0.2965 * pow ( Mach, -1.1506 ) + _Cd;
238 else if (Mach >= 0.7)
239 Cdm = 0.3742 * pow ( Mach, 2) - 0.252 * Mach + 0.0021 + _Cd;
241 Cdm = 0.0125 * Mach + _Cd;
243 //cout << " Mach , " << Mach << " , Cdm , " << Cdm << " ballistic speed kts //"<< speed << endl;
245 // drag = Cd * 0.5 * rho * speed * speed * drag_area;
246 // rho is adjusted for altitude in void FGAIBase::update,
247 // using Standard Atmosphere (sealevel temperature 15C)
248 // acceleration = drag/mass;
249 // adjust speed by drag
250 speed -= (Cdm * 0.5 * rho * speed * speed * _drag_area/_mass) * dt;
252 // don't let speed become negative
256 double speed_fps = speed * SG_KT_TO_FPS;
258 // calculate vertical and horizontal speed components
259 vs = sin( pitch * SG_DEGREES_TO_RADIANS ) * speed_fps;
260 double hs = cos( pitch * SG_DEGREES_TO_RADIANS ) * speed_fps;
262 // convert horizontal speed (fps) to degrees per second
263 speed_north_deg_sec = cos(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lat;
264 speed_east_deg_sec = sin(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lon;
266 // if wind not required, set to zero
268 _wind_from_north = 0;
272 // convert wind speed (fps) to degrees per second
273 wind_speed_from_north_deg_sec = _wind_from_north / ft_per_deg_lat;
274 wind_speed_from_east_deg_sec = _wind_from_east / ft_per_deg_lon;
277 pos.setLatitudeDeg( pos.getLatitudeDeg()
278 + (speed_north_deg_sec - wind_speed_from_north_deg_sec) * dt );
279 pos.setLongitudeDeg( pos.getLongitudeDeg()
280 + (speed_east_deg_sec - wind_speed_from_east_deg_sec) * dt );
282 // adjust vertical speed for acceleration of gravity and buoyancy
283 vs -= (_gravity - _buoyancy) * dt;
285 // adjust altitude (feet)
286 altitude_ft += vs * dt;
287 pos.setElevationFt(altitude_ft);
289 // recalculate pitch (velocity vector) if aerostabilized
290 /*cout << _name << ": " << "aero_stabilised " << _aero_stabilised
291 << " pitch " << pitch <<" vs " << vs <<endl ;*/
293 if (_aero_stabilised)
294 pitch = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
296 // recalculate total speed
297 speed = sqrt( vs * vs + hs * hs) / SG_KT_TO_FPS;
299 if (_impact && !_impact_data && vs < 0)
302 // set destruction flag if altitude less than sea level -1000
303 if (altitude_ft < -1000.0)
308 double FGAIBallistic::_getTime() const {
309 // cout << "life timer 2" << _life_timer << endl;
313 void FGAIBallistic::handle_impact() {
315 const SGMaterial* material;
317 // try terrain intersection
318 if (!globals->get_scenery()->get_elevation_m(pos.getLatitudeDeg(), pos.getLongitudeDeg(),
319 10000.0, elevation_m, &material))
323 const vector<string> names = material->get_names();
326 _mat_name = names[0].c_str();
328 _solid = material->get_solid();
329 _load_resistance = material->get_load_resistance();
330 props->setStringValue("material/name", _mat_name.c_str());
331 //cout << "material " << _mat_name << " solid " << _solid << " load " << _load_resistance << endl;
334 _ht_agl_ft = pos.getElevationFt() - elevation_m * SG_METER_TO_FEET;
336 // report impact by setting tied variables
337 if (_ht_agl_ft <= 0) {
340 _impact_lat = pos.getLatitudeDeg();
341 _impact_lon = pos.getLongitudeDeg();
342 _impact_elev = elevation_m;
343 _impact_speed = speed * SG_KT_TO_MPS;
344 _impact_energy = (_mass * slugs_to_kgs) * _impact_speed
345 * _impact_speed / (2 * 1000);
347 if (_impact_report_node)
348 _impact_report_node->setStringValue(props->getPath());