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() {
35 FGAIShip::~FGAIShip() {
39 bool FGAIShip::init() {
40 return FGAIBase::init();
45 void FGAIShip::update(double dt) {
54 void FGAIShip::Run(double dt) {
56 double turn_radius_ft;
57 double turn_circum_ft;
58 double speed_north_deg_sec;
59 double speed_east_deg_sec;
60 double ft_per_deg_lon;
61 double ft_per_deg_lat;
62 double dist_covered_ft;
65 // get size of a degree at this latitude
66 ft_per_deg_lat = 366468.96 - 3717.12 * cos(pos.lat() / 57.2958 );
67 ft_per_deg_lon = 365228.16 * cos(pos.lat() / 57.2958);
70 double speed_diff = tgt_speed - speed;
71 if (fabs(speed_diff) > 0.1) {
72 if (speed_diff > 0.0) speed += 0.1 * dt;
73 if (speed_diff < 0.0) speed -= 0.1 * dt;
76 // convert speed to degrees per second
77 speed_north_deg_sec = cos( hdg / 57.29577951 ) * speed * 1.686 / ft_per_deg_lat;
78 speed_east_deg_sec = sin( hdg / 57.29577951 ) * speed * 1.686 / ft_per_deg_lon;
81 pos.setlat( pos.lat() + speed_north_deg_sec * dt);
82 pos.setlon( pos.lon() + speed_east_deg_sec * dt);
84 // adjust heading based on current rudder angle
86 turn_radius_ft = 0.088362 * speed * speed / tan( fabs(rudder) / 57.2958 );
87 turn_circum_ft = 6.2831853 * turn_radius_ft;
88 dist_covered_ft = speed * 1.686 * dt;
89 alpha = dist_covered_ft / turn_circum_ft * 360.0;
90 hdg += alpha * sign( rudder );
91 if ( hdg > 360.0 ) hdg -= 360.0;
92 if ( hdg < 0.0) hdg += 360.0;
95 // adjust target rudder angle if heading lock engaged
97 double rudder_sense = 0.0;
98 double diff = fabs(hdg - tgt_heading);
99 if (diff > 180) diff = fabs(diff - 360);
100 double sum = hdg + diff;
101 if (sum > 360.0) sum -= 360.0;
102 if (fabs(sum - tgt_heading) < 1.0) {
107 if (diff < 30) tgt_roll = diff * rudder_sense;
110 // adjust rudder angle
111 double rudder_diff = tgt_roll - rudder;
112 if (fabs(rudder_diff) > 0.1) {
113 if (rudder_diff > 0.0) rudder += 5.0 * dt;
114 if (rudder_diff < 0.0) rudder -= 5.0 * dt;
120 void FGAIShip::AccelTo(double speed) {
125 void FGAIShip::PitchTo(double angle) {
130 void FGAIShip::RollTo(double angle) {
135 void FGAIShip::YawTo(double angle) {
139 void FGAIShip::ClimbTo(double altitude) {
143 void FGAIShip::TurnTo(double heading) {
144 tgt_heading = heading;
149 double FGAIShip::sign(double x) {
151 if ( x < 0.0 ) { return -1.0; }