1 // FGAIThermal - FGAIBase-derived class creates an AI thermal
3 // Written by David Culp, started Feb 2004.
5 // Copyright (C) 2004 David P. Culp - davidculp2@comcast.net
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
25 #include <simgear/math/point3d.hxx>
26 #include <Main/fg_props.hxx>
27 #include <Main/globals.hxx>
28 #include <Scenery/scenery.hxx>
34 #include "AIThermal.hxx"
37 FGAIThermal::FGAIThermal() : FGAIBase(otThermal) {
40 strength = factor = 0.0;
43 FGAIThermal::~FGAIThermal() {
46 void FGAIThermal::readFromScenario(SGPropertyNode* scFileNode) {
50 FGAIBase::readFromScenario(scFileNode);
52 setMaxStrength(scFileNode->getDoubleValue("strength-fps", 8.0));
53 setDiameter(scFileNode->getDoubleValue("diameter-ft", 0.0)/6076.11549);
54 setHeight(scFileNode->getDoubleValue("height-msl", 5000.0));
57 bool FGAIThermal::init() {
58 factor = 8.0 * max_strength / (diameter * diameter * diameter);
59 return FGAIBase::init();
62 void FGAIThermal::bind() {
66 void FGAIThermal::unbind() {
71 void FGAIThermal::update(double dt) {
78 void FGAIThermal::Run(double dt) {
80 //###########################//
81 // do calculations for range //
82 //###########################//
84 // copy values from the AIManager
85 double user_latitude = manager->get_user_latitude();
86 double user_longitude = manager->get_user_longitude();
87 double user_altitude = manager->get_user_altitude();
89 // calculate range to target in feet and nautical miles
90 double lat_range = fabs(pos.lat() - user_latitude) * ft_per_deg_lat;
91 double lon_range = fabs(pos.lon() - user_longitude) * ft_per_deg_lon;
92 double range_ft = sqrt(lat_range*lat_range + lon_range*lon_range);
93 range = range_ft / 6076.11549;
95 // Calculate speed of rising air if within range.
96 // Air vertical speed is maximum at center of thermal,
97 // and decreases to zero at the edge (as distance cubed).
98 if (range < (diameter * 0.5)) {
99 strength = max_strength - ( range * range * range * factor );
104 // Stop lift at the top of the thermal (smoothly)
105 if (user_altitude > (height + 100.0)) {
108 else if (user_altitude < height) {
112 strength -= (strength * (user_altitude - height) * 0.01);