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Commit 6ea3b46a authored by deuce's avatar deuce
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Maidenhead object which can calculate the distance and bearing to another 

Maidenhead object.
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function Maidenhead(locator, latitude, longitude, precision)
{
this.locator = locator;
this.longitude = longitude;
this.latitude = latitude;
this.precision = precision;
var lop;
var lap;
var ucl;
var stupidhack;
var i;
function parselocator(locator) {
function add_pos(subloc, pos) {
if (this.positions[pos].range == 10) {
lop = subloc.charCodeAt(0) - '0'.charCodeAt();
lap = subloc.charCodeAt(1) - '0'.charCodeAt();
} else {
lop = subloc.charCodeAt(0) - 'A'.charCodeAt();
lap = subloc.charCodeAt(1) - 'A'.charCodeAt();
}
if (lap < 0 || lop < 0 || lap >= this.positions[pos].range || lop >= this.positions[pos].range)
throw('invalid field in locator');
this.longitude += this.positions[pos].precision * lop;
this.latitude += this.positions[pos].precision / 2 * lap;
}
ucl = locator.toUpperCase();
if (ucl.length > 18)
throw('locator too precise');
if (ucl.length & 1)
throw('locator length is odd');
this.latitude = -90.0;
this.longitude = -180.0;
this.precision = 0;
while (ucl.length >= 2) {
add_pos.call(this, ucl.substr(0, 2), this.precision);
ucl = ucl.substr(2);
this.precision += 1;
}
this.south_west = {'longitude': this.longitude, 'latitude': this.latitude};
this.north_west = {'longitude': this.longitude, 'latitude': this.latitude + this.positions[this.precision-1].precision / 2};
this.south_east = {'longitude': this.longitude + this.positions[this.precision-1].precision, 'latitude': this.latitude};
this.north_east = {'longitude': this.longitude + this.positions[this.precision-1].precision, 'latitude': this.latitude + this.positions[this.precision-1].precision / 2};
this.longitude += this.positions[this.precision-1].precision / 2;
this.latitude += this.positions[this.precision-1].precision / 4;
this.locator = locator;
}
function sub_pos(hack, pos) {
lop = parseInt(hack.longitude / this.positions[pos].precision, 10);
lap = parseInt(hack.latitude / (this.positions[pos].precision / 2), 10);
if (lap < 0 || lop < 0 || lap >= this.positions[pos].range || lop >= this.positions[pos].range)
throw('invalid latitude or longitude');
if (this.positions[pos].range == 10) {
hack.locator = hack.locator + String.fromCharCode('0'.charCodeAt()+lop);
hack.locator = hack.locator + String.fromCharCode('0'.charCodeAt()+lap);
} else if (this.positions[pos].range == 18) {
hack.locator = hack.locator + String.fromCharCode('A'.charCodeAt()+lop);
hack.locator = hack.locator + String.fromCharCode('A'.charCodeAt()+lap);
} else {
hack.locator = hack.locator + String.fromCharCode('a'.charCodeAt()+lop);
hack.locator = hack.locator + String.fromCharCode('a'.charCodeAt()+lap);
}
hack.longitude -= lop * this.positions[pos].precision;
hack.latitude -= lap * (this.positions[pos].precision / 2);
}
if (locator !== undefined) {
parselocator.call(this, locator);
} else {
if (latitude === undefined || longitude === undefined || precision === undefined)
throw('must specify locator or lat, lon, precision');
if (latitude < -90 || latitude > 90)
throw('Invalid latitude');
if (longitude < -180 || longitude > 180)
throw('Invalid longitude');
stupidhack = {'latitude': latitude + 90, 'longitude': longitude + 180, 'locator': ''};
for (i=0; i<precision; i++)
sub_pos.call(this, stupidhack, i);
parselocator(stupidhack.locator);
}
}
Maidenhead.prototype.positions = [
{'precision': 20.0, 'range': 18},
{'precision': 2.0, 'range':10},
{'precision': 2.0/24, 'range': 24},
{'precision': 2.0/240, 'range': 10},
{'precision': 2.0/5760, 'range': 24},
{'precision': 2.0/57600, 'range': 10},
{'precision': 2.0/115200, 'range': 10},
{'precision': 2.0/276480000, 'range': 24},
{'precision': 2.0/2764800000, 'range': 10}
];
Maidenhead.prototype.distance = function(to)
{
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Latitude/longitude spherical geodesy tools (c) Chris Veness 2002-2017 */
/* MIT Licence */
/* www.movable-type.co.uk/scripts/latlong.html */
/* www.movable-type.co.uk/scripts/geodesy/docs/module-latlon-spherical.html */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
var radius;
var rlatfrom;
var rlatto;
var rlonfrom;
var rlonto;
var rlondiff;
var rlatdiff;
var a;
var c;
if (!(to instanceof Maidenhead))
throw('argument must be a Maidenhead');
radius = 6371e3;
rlatfrom = this.latitude * (Math.PI / 180);
rlatto = to.latitude * (Math.PI / 180);
rlonfrom = this.longitude * (Math.PI / 180);
rlonto = to.longitude * (Math.PI / 180);
rlondiff = rlonto - rlonfrom;
rlatdiff = rlatto - rlatfrom;
a = Math.sin(rlatdiff/2)*Math.sin(rlatdiff/2)+Math.cos(rlatfrom)*Math.cos(rlatto)*Math.sin(rlondiff/2)*Math.sin(rlondiff/2);
c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
return radius * c;
};
Maidenhead.prototype.bearing = function(to)
{
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Latitude/longitude spherical geodesy tools (c) Chris Veness 2002-2017 */
/* MIT Licence */
/* www.movable-type.co.uk/scripts/latlong.html */
/* www.movable-type.co.uk/scripts/geodesy/docs/module-latlon-spherical.html */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
var rlatfrom;
var rlatto;
var rlondiff;
var y;
var x;
var rbear;
if (!(to instanceof Maidenhead))
throw('argument must be a Maidenhead');
rlatfrom = this.latitude * (Math.PI / 180);
rlatto = to.latitude * (Math.PI / 180);
rlondiff = to.longitude - this.longitude;
y = Math.sin(rlondiff) * Math.cos(rlatto);
x = Math.cos(rlatfrom)*Math.sin(rlatto)-Math.sin(rlatfrom)*Math.cos(rlatto)*Math.cos(rlondiff);
rbear = Math.atan2(y, x);
return ((rbear / (Math.PI / 180))+360) % 360;
};
Maidenhead.prototype.vdistance = function(to)
{
if (!(to instanceof Maidenhead))
throw('argument must be a Maidenhead');
try {
return this.vinverse(to).distance;
} catch (e) {
return undefined;
}
};
Maidenhead.prototype.vbearing = function(to)
{
if (!(to instanceof Maidenhead))
throw('argument must be a Maidenhead');
try {
return this.vinverse(to).initialBearing;
} catch (e) {
return undefined;
}
};
Maidenhead.prototype.vinverse = function(to)
{
// Adapted from: https://www.movable-type.co.uk/scripts/latlong-vincenty.html
// using the WGS-84 ellipsoid.
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Vincenty Direct and Inverse Solution of Geodesics on the Ellipsoid (c) Chris Veness 2002-2017 */
/* MIT Licence */
/* www.movable-type.co.uk/scripts/latlong-vincenty.html */
/* www.movable-type.co.uk/scripts/geodesy/docs/module-latlon-vincenty.html */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
var p1, p2;
var rlat1, rlat2;
var a, b, f;
var L;
var tanU1, cosU1, sinU1, tanU2, cosU2, sinU2;
var sinsig, cossig, sig, cosSqalpg, cos2sigM;
var rlon, iterations, antimeridian;
var sinrlon, cosrlon;
var sinSqsig, sinalph, cidenheaosSqalph, cosSqalph, C, rlonprime, iterationCheck;
var uSq, A, B, delatsig, s, alph1, alph2, ret, rlon1, rlon2;
if (!(to instanceof Maidenhead))
throw('argument must be a Maidenhead');
p1 = {'lat': this.latitude, 'lon': this.longitude};
p2 = {'lat': to.latitude, 'lon': to.longitude};
if (p1.lon == -180.0)
p1.lon = 180.0;
rlat1 = p1.lat * (Math.PI / 180);
rlon1 = p1.lon * (Math.PI / 180);
rlat2 = p2.lat * (Math.PI / 180);
rlon2 = p2.lon * (Math.PI / 180);
// TODO: Get these values...
a = 6378137.0;
b = 6356752.3142;
f = 1.0/298.257223563;
L = rlon2 - rlon1;
tanU1 = (1.0-f) * Math.tan(rlat1);
cosU1 = 1.0 / Math.sqrt((1.0 + tanU1*tanU1));
sinU1 = tanU1 * cosU1;
tanU2 = (1.0-f) * Math.tan(rlat2);
cosU2 = 1.0 / Math.sqrt((1.0 + tanU2*tanU2));
sinU2 = tanU2 * cosU2;
sinsig=0.0;
cossig=0.0;
sig=0.0;
cosSqalph=0.0;
cos2sigM=0.0;
rlon = L;
iterations = 0.0;
antimeridian = Math.abs(L) > Math.PI;
for (;;) {
sinrlon = Math.sin(rlon);
cosrlon = Math.cos(rlon);
sinSqsig = (cosU2*sinrlon) * (cosU2*sinrlon) + (cosU1*sinU2-sinU1*cosU2*cosrlon) * (cosU1*sinU2-sinU1*cosU2*cosrlon);
if (sinSqsig == 0)
break; // co-incident points
sinsig = Math.sqrt(sinSqsig);
cossig = sinU1*sinU2 + cosU1*cosU2*cosrlon;
sig = Math.atan2(sinsig, cossig);
sinalph = cosU1 * cosU2 * sinrlon / sinsig;
cidenheaosSqalph = 1 - sinalph*sinalph;
if (cosSqalph != 0)
cos2sigM = cossig - 2.0*sinU1*sinU2/cosSqalph;
else
cos2sigM = 0.0; // equatorial
C = f/16.0*cosSqalph*(4.0+f*(4.0-3.0*cosSqalph));
rlonprime = rlon;
rlon = L + (1.0-C) * f * sinalph * (sig + C*sinsig*(cos2sigM+C*cossig*(-1.0+2.0*cos2sigM*cos2sigM)));
if (antimeridian)
iterationCheck = Math.abs(rlon)-Math.PI;
else
iterationCheck = Math.abs(rlon);
if (iterationCheck > Math.PI)
throw('rlon > pi');
iterations += 1;
if (iterations >= 1000)
throw('Formula failed to converge');
if (Math.abs(rlon-rlonprime) <= 1e-12)
break;
}
uSq = cosSqalph * (a*a - b*b) / (b*b);
A = 1.0 + uSq/16384.0*(4096.0+uSq*(-768.0+uSq*(320.0-175.0*uSq)));
B = uSq/1024.0 * (256.0+uSq*(-128.0+uSq*(74.0-47.0*uSq)));
delatsig = B*sinsig*(cos2sigM+B/4.0*(cossig*(-1.0+2.0*cos2sigM*cos2sigM)-
B/6.0*cos2sigM*(-3.0+4.0*sinsig*sinsig)*(-3.0+4.0*cos2sigM*cos2sigM)));
s = b*A*(sig-delatsig);
alph1 = Math.atan2(cosU2*sinrlon, cosU1*sinU2-sinU1*cosU2*cosrlon);
alph2 = Math.atan2(cosU1*sinrlon, -sinU1*cosU2+cosU1*sinU2*cosrlon);
alph1 = (alph1 + 2.0*Math.PI) % (2.0*Math.PI); // normalise to 0..360
alph2 = (alph2 + 2.0*Math.PI) % (2.0*Math.PI); // normalise to 0..360
ret = { 'distance': s, 'iterations': iterations};
if (s === 0) {
ret.initialBearing = undefined;
ret.finalBearing = undefined;
} else {
ret.initialBearing = alph1 / (Math.PI / 180);
ret.finalBearing = alph2 / (Math.PI / 180);
}
return ret;
};
var here = new Maidenhead('EN72gw');
print(here.distance(new Maidenhead('DM13dp')));
print(here.vdistance(new Maidenhead('DM13dp')));
print(here.bearing(new Maidenhead('DM13dp')));
print(here.bearing(new Maidenhead('DM13dp')));
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