1 // FGAIShip - FGAIBase-derived class creates an AI ship
3 // Written by David Culp, started October 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>
30 FGAIShip::FGAIShip(FGAIManager* mgr) {
39 FGAIShip::~FGAIShip() {
43 bool FGAIShip::init() {
44 return FGAIBase::init();
47 void FGAIShip::bind() {
50 props->tie("surface-positions/rudder-pos-deg",
51 SGRawValuePointer<double>(&rudder));
53 props->setStringValue("name", name.c_str());
56 void FGAIShip::unbind() {
58 props->untie("surface-positions/rudder-pos-deg");
61 void FGAIShip::update(double dt) {
70 void FGAIShip::Run(double dt) {
72 if (fp) ProcessFlightPlan(dt);
74 double sp_turn_radius_ft;
75 double rd_turn_radius_ft;
76 double speed_north_deg_sec;
77 double speed_east_deg_sec;
78 double dist_covered_ft;
82 double speed_diff = tgt_speed - speed;
83 if (fabs(speed_diff) > 0.1) {
84 if (speed_diff > 0.0) speed += 0.1 * dt;
85 if (speed_diff < 0.0) speed -= 0.1 * dt;
88 // convert speed to degrees per second
89 speed_north_deg_sec = cos( hdg / SGD_RADIANS_TO_DEGREES )
90 * speed * 1.686 / ft_per_deg_lat;
91 speed_east_deg_sec = sin( hdg / SGD_RADIANS_TO_DEGREES )
92 * speed * 1.686 / ft_per_deg_lon;
95 pos.setlat( pos.lat() + speed_north_deg_sec * dt);
96 pos.setlon( pos.lon() + speed_east_deg_sec * dt);
99 // adjust heading based on current rudder angle
101 /* turn_radius_ft = 0.088362 * speed * speed
102 / tan( fabs(rudder) / SG_RADIANS_TO_DEGREES );
103 turn_circum_ft = SGD_2PI * turn_radius_ft;
104 dist_covered_ft = speed * 1.686 * dt;
105 alpha = dist_covered_ft / turn_circum_ft * 360.0;*/
107 if (turn_radius_ft <= 0) turn_radius_ft = 0; // don't allow nonsense values
109 // cout << "speed " << speed << " turn radius " << turn_radius_ft << endl;
111 // adjust turn radius for speed. The equation is very approximate.
112 sp_turn_radius_ft = 10 * pow ((speed - 15),2) + turn_radius_ft;
113 // cout << "speed " << speed << " speed turn radius " << sp_turn_radius_ft << endl;
115 // adjust turn radius for rudder angle. The equation is even more approximate.
116 rd_turn_radius_ft = -130 * (rudder - 15) + sp_turn_radius_ft;
117 // cout << "rudder " << rudder << " rudder turn radius " << rd_turn_radius_ft << endl;
119 // calculate the angle, alpha, subtended by the arc traversed in time dt
120 alpha = ((speed * 1.686 * dt)/rd_turn_radius_ft) * SG_RADIANS_TO_DEGREES;
122 // make sure that alpha is applied in the right direction
124 hdg += alpha * sign( rudder );
126 if ( hdg > 360.0 ) hdg -= 360.0;
127 if ( hdg < 0.0) hdg += 360.0;
129 //adjust roll for rudder angle and speed
130 roll = - ( speed / 2 - rudder / 6 );
132 // cout << " hdg " << hdg << "roll "<< roll << endl;
135 // adjust target rudder angle if heading lock engaged
137 double rudder_sense = 0.0;
138 double diff = fabs(hdg - tgt_heading);
139 if (diff > 180) diff = fabs(diff - 360);
140 double sum = hdg + diff;
141 if (sum > 360.0) sum -= 360.0;
142 if (fabs(sum - tgt_heading) < 1.0) {
147 if (diff < 30) tgt_roll = diff * rudder_sense;
150 // adjust rudder angle
151 double rudder_diff = tgt_roll - rudder;
152 if (fabs(rudder_diff) > 0.1) {
153 if (rudder_diff > 0.0) rudder += 5.0 * dt;
154 if (rudder_diff < 0.0) rudder -= 5.0 * dt;
160 void FGAIShip::AccelTo(double speed) {
165 void FGAIShip::PitchTo(double angle) {
170 void FGAIShip::RollTo(double angle) {
175 void FGAIShip::YawTo(double angle) {
179 void FGAIShip::ClimbTo(double altitude) {
183 void FGAIShip::TurnTo(double heading) {
184 tgt_heading = heading;
189 double FGAIShip::sign(double x) {
191 if ( x < 0.0 ) { return -1.0; }
195 void FGAIShip::setFlightPlan(FGAIFlightPlan* f) {
199 void FGAIShip::setName(const string& n) {
203 void FGAIShip::ProcessFlightPlan(double dt) {
204 // not implemented yet