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";
38 FGAIBallistic::~FGAIBallistic() {
42 bool FGAIBallistic::init() {
44 aero_stabilized = true;
50 void FGAIBallistic::bind() {
52 props->tie("sim/time/elapsed-sec", SGRawValuePointer<double>(&life_timer));
55 void FGAIBallistic::unbind() {
56 // FGAIBase::unbind();
57 props->untie("sim/time/elapsed-sec");
60 void FGAIBallistic::update(double dt) {
67 void FGAIBallistic::setAzimuth(double az) {
72 void FGAIBallistic::setElevation(double el) {
73 pitch = elevation = el;
77 void FGAIBallistic::setStabilization(bool val) {
78 aero_stabilized = val;
81 void FGAIBallistic::setDragArea(double a) {
85 void FGAIBallistic::setLife(double seconds) {
89 void FGAIBallistic::Run(double dt) {
92 if (life_timer > life) setDie(true);
94 double speed_north_deg_sec;
95 double speed_east_deg_sec;
97 // the two drag calculations below assume sea-level density,
98 // mass of 0.03 slugs, drag coeff of 0.295
99 // adjust speed due to drag
100 speed -= 0.0116918 * drag_area * speed * speed * dt;
101 if ( speed < 0.0 ) speed = 0.0;
102 vs = sin( pitch * SG_DEGREES_TO_RADIANS ) * speed;
103 hs = cos( pitch * SG_DEGREES_TO_RADIANS ) * speed;
105 // convert horizontal speed (fps) to degrees per second
106 speed_north_deg_sec = cos(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lat;
107 speed_east_deg_sec = sin(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lon;
110 pos.setlat( pos.lat() + speed_north_deg_sec * dt);
111 pos.setlon( pos.lon() + speed_east_deg_sec * dt);
113 // adjust altitude (feet)
115 pos.setelev(altitude * SG_FEET_TO_METER);
117 // adjust vertical speed for acceleration of gravity
120 // recalculate pitch (velocity vector) if aerostabilized
121 if (aero_stabilized) pitch = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
123 // recalculate total speed
124 speed = sqrt( vs * vs + hs * hs);
126 // set destruction flag if altitude less than sea level -1000
127 if (altitude < -1000.0) setDie(true);