92 lines
2.3 KiB
JavaScript
92 lines
2.3 KiB
JavaScript
import adjust_lon from '../common/adjust_lon';
|
|
import asinz from '../common/asinz';
|
|
import {EPSLN, HALF_PI} from '../constants/values';
|
|
|
|
export function init() {
|
|
//double temp; /* temporary variable */
|
|
|
|
/* Place parameters in static storage for common use
|
|
-------------------------------------------------*/
|
|
this.sin_p14 = Math.sin(this.lat0);
|
|
this.cos_p14 = Math.cos(this.lat0);
|
|
}
|
|
|
|
/* Orthographic forward equations--mapping lat,long to x,y
|
|
---------------------------------------------------*/
|
|
export function forward(p) {
|
|
var sinphi, cosphi; /* sin and cos value */
|
|
var dlon; /* delta longitude value */
|
|
var coslon; /* cos of longitude */
|
|
var ksp; /* scale factor */
|
|
var g, x, y;
|
|
var lon = p.x;
|
|
var lat = p.y;
|
|
/* Forward equations
|
|
-----------------*/
|
|
dlon = adjust_lon(lon - this.long0);
|
|
|
|
sinphi = Math.sin(lat);
|
|
cosphi = Math.cos(lat);
|
|
|
|
coslon = Math.cos(dlon);
|
|
g = this.sin_p14 * sinphi + this.cos_p14 * cosphi * coslon;
|
|
ksp = 1;
|
|
if ((g > 0) || (Math.abs(g) <= EPSLN)) {
|
|
x = this.a * ksp * cosphi * Math.sin(dlon);
|
|
y = this.y0 + this.a * ksp * (this.cos_p14 * sinphi - this.sin_p14 * cosphi * coslon);
|
|
}
|
|
p.x = x;
|
|
p.y = y;
|
|
return p;
|
|
}
|
|
|
|
export function inverse(p) {
|
|
var rh; /* height above ellipsoid */
|
|
var z; /* angle */
|
|
var sinz, cosz; /* sin of z and cos of z */
|
|
var con;
|
|
var lon, lat;
|
|
/* Inverse equations
|
|
-----------------*/
|
|
p.x -= this.x0;
|
|
p.y -= this.y0;
|
|
rh = Math.sqrt(p.x * p.x + p.y * p.y);
|
|
z = asinz(rh / this.a);
|
|
|
|
sinz = Math.sin(z);
|
|
cosz = Math.cos(z);
|
|
|
|
lon = this.long0;
|
|
if (Math.abs(rh) <= EPSLN) {
|
|
lat = this.lat0;
|
|
p.x = lon;
|
|
p.y = lat;
|
|
return p;
|
|
}
|
|
lat = asinz(cosz * this.sin_p14 + (p.y * sinz * this.cos_p14) / rh);
|
|
con = Math.abs(this.lat0) - HALF_PI;
|
|
if (Math.abs(con) <= EPSLN) {
|
|
if (this.lat0 >= 0) {
|
|
lon = adjust_lon(this.long0 + Math.atan2(p.x, - p.y));
|
|
}
|
|
else {
|
|
lon = adjust_lon(this.long0 - Math.atan2(-p.x, p.y));
|
|
}
|
|
p.x = lon;
|
|
p.y = lat;
|
|
return p;
|
|
}
|
|
lon = adjust_lon(this.long0 + Math.atan2((p.x * sinz), rh * this.cos_p14 * cosz - p.y * this.sin_p14 * sinz));
|
|
p.x = lon;
|
|
p.y = lat;
|
|
return p;
|
|
}
|
|
|
|
export var names = ["ortho"];
|
|
export default {
|
|
init: init,
|
|
forward: forward,
|
|
inverse: inverse,
|
|
names: names
|
|
};
|