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() {
36 FGAIShip::~FGAIShip() {
40 bool FGAIShip::init() {
41 return FGAIBase::init();
44 void FGAIShip::bind() {
47 props->tie("surface-positions/rudder-pos-norm",
48 SGRawValuePointer<double>(&rudder));
51 void FGAIShip::unbind() {
55 void FGAIShip::update(double dt) {
64 void FGAIShip::Run(double dt) {
66 double turn_radius_ft;
67 double turn_circum_ft;
68 double speed_north_deg_sec;
69 double speed_east_deg_sec;
70 double ft_per_deg_lon;
71 double ft_per_deg_lat;
72 double dist_covered_ft;
75 // get size of a degree at this latitude
76 ft_per_deg_lat = 366468.96 - 3717.12 * cos(pos.lat()/SG_RADIANS_TO_DEGREES);
77 ft_per_deg_lon = 365228.16 * cos(pos.lat() / SG_RADIANS_TO_DEGREES);
80 double speed_diff = tgt_speed - speed;
81 if (fabs(speed_diff) > 0.1) {
82 if (speed_diff > 0.0) speed += 0.1 * dt;
83 if (speed_diff < 0.0) speed -= 0.1 * dt;
86 // convert speed to degrees per second
87 speed_north_deg_sec = cos( hdg / SG_RADIANS_TO_DEGREES )
88 * speed * 1.686 / ft_per_deg_lat;
89 speed_east_deg_sec = sin( hdg / SG_RADIANS_TO_DEGREES )
90 * speed * 1.686 / ft_per_deg_lon;
93 pos.setlat( pos.lat() + speed_north_deg_sec * dt);
94 pos.setlon( pos.lon() + speed_east_deg_sec * dt);
96 // adjust heading based on current rudder angle
98 turn_radius_ft = 0.088362 * speed * speed
99 / tan( fabs(rudder) / SG_RADIANS_TO_DEGREES );
100 turn_circum_ft = SGD_2PI * turn_radius_ft;
101 dist_covered_ft = speed * 1.686 * dt;
102 alpha = dist_covered_ft / turn_circum_ft * 360.0;
103 hdg += alpha * sign( rudder );
104 if ( hdg > 360.0 ) hdg -= 360.0;
105 if ( hdg < 0.0) hdg += 360.0;
108 // adjust target rudder angle if heading lock engaged
110 double rudder_sense = 0.0;
111 double diff = fabs(hdg - tgt_heading);
112 if (diff > 180) diff = fabs(diff - 360);
113 double sum = hdg + diff;
114 if (sum > 360.0) sum -= 360.0;
115 if (fabs(sum - tgt_heading) < 1.0) {
120 if (diff < 30) tgt_roll = diff * rudder_sense;
123 // adjust rudder angle
124 double rudder_diff = tgt_roll - rudder;
125 if (fabs(rudder_diff) > 0.1) {
126 if (rudder_diff > 0.0) rudder += 5.0 * dt;
127 if (rudder_diff < 0.0) rudder -= 5.0 * dt;
133 void FGAIShip::AccelTo(double speed) {
138 void FGAIShip::PitchTo(double angle) {
143 void FGAIShip::RollTo(double angle) {
148 void FGAIShip::YawTo(double angle) {
152 void FGAIShip::ClimbTo(double altitude) {
156 void FGAIShip::TurnTo(double heading) {
157 tgt_heading = heading;
162 double FGAIShip::sign(double x) {
164 if ( x < 0.0 ) { return -1.0; }