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flightgear/src/ATC/ATCutils.cxx

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C++

// ATCutils.cxx - Utility functions for the ATC / AI system
//
// Written by David Luff, started March 2002.
//
// Copyright (C) 2002 David C Luff - david.luff@nottingham.ac.uk
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#include <math.h>
#include <simgear/math/point3d.hxx>
#include <simgear/constants.h>
#include <plib/sg.h>
//#include <iomanip.h>
#include "ATCutils.hxx"
// Convert any number to spoken digits
string ConvertNumToSpokenDigits(string n) {
//cout << "n = " << n << endl;
string nums[10] = {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};
string pt = "decimal";
string str = "";
for(unsigned int i=0; i<n.length(); ++i) {
//cout << "n.substr(" << i << ",1 = " << n.substr(i,1) << endl;
if(n.substr(i,1) == " ") {
// do nothing
} else if(n.substr(i,1) == ".") {
str += pt;
} else {
str += nums[atoi((n.substr(i,1)).c_str())];
}
if(i != (n.length()-1)) { // ie. don't add a space at the end.
str += " ";
}
}
return(str);
}
// Convert a 2 digit rwy number to a spoken-style string
string ConvertRwyNumToSpokenString(int n) {
string nums[10] = {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};
// Basic error/sanity checking
while(n < 0) {
n += 36;
}
while(n > 36) {
n -= 36;
}
if(n == 0) {
n = 36; // Is this right?
}
string str = "";
int index = n/10;
str += nums[index];
n -= (index * 10);
//str += "-";
str += " "; //Changed this for the benefit of the voice token parser - prefer the "-" in the visual output though.
str += nums[n];
return(str);
}
// Return the phonetic letter of a letter represented as an integer 1->26
string GetPhoneticIdent(int i) {
// TODO - Check i is between 1 and 26 and wrap if necessary
switch(i) {
case 1 : return("alpha");
case 2 : return("bravo");
case 3 : return("charlie");
case 4 : return("delta");
case 5 : return("echo");
case 6 : return("foxtrot");
case 7 : return("golf");
case 8 : return("hotel");
case 9 : return("india");
case 10 : return("juliet");
case 11 : return("kilo");
case 12 : return("lima");
case 13 : return("mike");
case 14 : return("november");
case 15 : return("oscar");
case 16 : return("papa");
case 17 : return("quebec");
case 18 : return("romeo");
case 19 : return("sierra");
case 20 : return("tango");
case 21 : return("uniform");
case 22 : return("victor");
case 23 : return("whiskey");
case 24 : return("x-ray");
case 25 : return("yankee");
case 26 : return("zulu");
}
// We shouldn't get here
return("Error");
}
// Given two positions (lat & lon in degrees), get the HORIZONTAL separation (in meters)
double dclGetHorizontalSeparation(Point3D pos1, Point3D pos2) {
double x; //East-West separation
double y; //North-South separation
double z; //Horizontal separation - z = sqrt(x^2 + y^2)
double lat1 = pos1.lat() * SG_DEGREES_TO_RADIANS;
double lon1 = pos1.lon() * SG_DEGREES_TO_RADIANS;
double lat2 = pos2.lat() * SG_DEGREES_TO_RADIANS;
double lon2 = pos2.lon() * SG_DEGREES_TO_RADIANS;
y = sin(fabs(lat1 - lat2)) * SG_EQUATORIAL_RADIUS_M;
x = sin(fabs(lon1 - lon2)) * SG_EQUATORIAL_RADIUS_M * (cos((lat1 + lat2) / 2.0));
z = sqrt(x*x + y*y);
return(z);
}
// Given a point and a line, get the HORIZONTAL shortest distance from the point to a point on the line.
// Expects to be fed orthogonal co-ordinates, NOT lat & lon !
// The units of the separation will be those of the input.
double dclGetLinePointSeparation(double px, double py, double x1, double y1, double x2, double y2) {
double vecx = x2-x1;
double vecy = y2-y1;
double magline = sqrt(vecx*vecx + vecy*vecy);
double u = ((px-x1)*(x2-x1) + (py-y1)*(y2-y1)) / (magline * magline);
double x0 = x1 + u*(x2-x1);
double y0 = y1 + u*(y2-y1);
vecx = px - x0;
vecy = py - y0;
double d = sqrt(vecx*vecx + vecy*vecy);
if(d < 0) {
d *= -1;
}
return(d);
}
// Given a position (lat/lon/elev), heading and vertical angle (degrees), and distance (meters), calculate the new position.
// This function assumes the world is spherical. If geodetic accuracy is required use the functions is sg_geodesy instead!
// Assumes that the ground is not hit!!! Expects heading and angle in degrees, distance in meters.
Point3D dclUpdatePosition(Point3D pos, double heading, double angle, double distance) {
//cout << setprecision(10) << pos.lon() << ' ' << pos.lat() << '\n';
heading *= DCL_DEGREES_TO_RADIANS;
angle *= DCL_DEGREES_TO_RADIANS;
double lat = pos.lat() * DCL_DEGREES_TO_RADIANS;
double lon = pos.lon() * DCL_DEGREES_TO_RADIANS;
double elev = pos.elev();
//cout << setprecision(10) << lon*DCL_RADIANS_TO_DEGREES << ' ' << lat*DCL_RADIANS_TO_DEGREES << '\n';
double horiz_dist = distance * cos(angle);
double vert_dist = distance * sin(angle);
double north_dist = horiz_dist * cos(heading);
double east_dist = horiz_dist * sin(heading);
//cout << distance << ' ' << horiz_dist << ' ' << vert_dist << ' ' << north_dist << ' ' << east_dist << '\n';
double delta_lat = asin(north_dist / (double)SG_EQUATORIAL_RADIUS_M);
double delta_lon = asin(east_dist / (double)SG_EQUATORIAL_RADIUS_M) * (1.0 / cos(lat)); // I suppose really we should use the average of the original and new lat but we'll assume that this will be good enough.
//cout << delta_lon*DCL_RADIANS_TO_DEGREES << ' ' << delta_lat*DCL_RADIANS_TO_DEGREES << '\n';
lat += delta_lat;
lon += delta_lon;
elev += vert_dist;
//cout << setprecision(10) << lon*DCL_RADIANS_TO_DEGREES << ' ' << lat*DCL_RADIANS_TO_DEGREES << '\n';
//cout << setprecision(15) << DCL_DEGREES_TO_RADIANS * DCL_RADIANS_TO_DEGREES << '\n';
return(Point3D(lon*DCL_RADIANS_TO_DEGREES, lat*DCL_RADIANS_TO_DEGREES, elev));
}
// Get a heading in degrees from one lat/lon to another.
// This function assumes the world is spherical. If geodetic accuracy is required use the functions is sg_geodesy instead!
// Warning - at the moment we are not checking for identical points - currently it returns 90 in this instance.
double GetHeadingFromTo(Point3D A, Point3D B) {
double latA = A.lat() * DCL_DEGREES_TO_RADIANS;
double lonA = A.lon() * DCL_DEGREES_TO_RADIANS;
double latB = B.lat() * DCL_DEGREES_TO_RADIANS;
double lonB = B.lon() * DCL_DEGREES_TO_RADIANS;
double xdist = sin(lonB - lonA) * (double)SG_EQUATORIAL_RADIUS_M * cos((latA+latB)/2.0);
double ydist = sin(latB - latA) * (double)SG_EQUATORIAL_RADIUS_M;
if(xdist >= 0) {
if(ydist > 0) {
return(atan(xdist/ydist) * DCL_RADIANS_TO_DEGREES);
} else if (ydist == 0) {
return(90.0);
} else {
return(180.0 - atan(xdist/fabs(ydist)) * DCL_RADIANS_TO_DEGREES);
}
} else {
if(ydist > 0) {
return(360.0 - atan(fabs(xdist)/ydist) * DCL_RADIANS_TO_DEGREES);
} else if (ydist == 0) {
return(270.0);
} else {
return(180.0 + atan(xdist/ydist) * DCL_RADIANS_TO_DEGREES);
}
}
}
// Given a heading (in degrees), bound it from 0 -> 360
void dclBoundHeading(double &hdg) {
while(hdg < 0.0) {
hdg += 360.0;
}
while(hdg > 360.0) {
hdg -= 360.0;
}
}