sterea.js
1.59 KB
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Proj4js.Proj.sterea = {
dependsOn : 'gauss',
init : function() {
Proj4js.Proj['gauss'].init.apply(this);
if (!this.rc) {
Proj4js.reportError("sterea:init:E_ERROR_0");
return;
}
this.sinc0 = Math.sin(this.phic0);
this.cosc0 = Math.cos(this.phic0);
this.R2 = 2.0 * this.rc;
if (!this.title) this.title = "Oblique Stereographic Alternative";
},
forward : function(p) {
p.x = Proj4js.common.adjust_lon(p.x-this.long0); /* adjust del longitude */
Proj4js.Proj['gauss'].forward.apply(this, [p]);
sinc = Math.sin(p.y);
cosc = Math.cos(p.y);
cosl = Math.cos(p.x);
k = this.k0 * this.R2 / (1.0 + this.sinc0 * sinc + this.cosc0 * cosc * cosl);
p.x = k * cosc * Math.sin(p.x);
p.y = k * (this.cosc0 * sinc - this.sinc0 * cosc * cosl);
p.x = this.a * p.x + this.x0;
p.y = this.a * p.y + this.y0;
return p;
},
inverse : function(p) {
var lon,lat;
p.x = (p.x - this.x0) / this.a; /* descale and de-offset */
p.y = (p.y - this.y0) / this.a;
p.x /= this.k0;
p.y /= this.k0;
if ( (rho = Math.sqrt(p.x*p.x + p.y*p.y)) ) {
c = 2.0 * Math.atan2(rho, this.R2);
sinc = Math.sin(c);
cosc = Math.cos(c);
lat = Math.asin(cosc * this.sinc0 + p.y * sinc * this.cosc0 / rho);
lon = Math.atan2(p.x * sinc, rho * this.cosc0 * cosc - p.y * this.sinc0 * sinc);
} else {
lat = this.phic0;
lon = 0.;
}
p.x = lon;
p.y = lat;
Proj4js.Proj['gauss'].inverse.apply(this,[p]);
p.x = Proj4js.common.adjust_lon(p.x + this.long0); /* adjust longitude to CM */
return p;
}
};