mirror of
https://github.com/jiawanlong/Cesium-Examples.git
synced 2025-07-07 16:57:30 +00:00
248 lines
7.1 KiB
JavaScript
248 lines
7.1 KiB
JavaScript
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// Initialize the Stereographic projection
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Proj4js.Proj.stere = {
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ssfn_: function(phit, sinphi, eccen) {
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sinphi *= eccen;
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return (Math.tan (.5 * (Proj4js.common.HALF_PI + phit)) * Math.pow((1. - sinphi) / (1. + sinphi), .5 * eccen));
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},
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TOL: 1.e-8,
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NITER: 8,
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CONV: 1.e-10,
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S_POLE: 0,
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N_POLE: 1,
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OBLIQ: 2,
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EQUIT: 3,
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init: function() {
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this.phits = this.lat_ts ? this.lat_ts : Proj4js.common.HALF_PI;
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var t = Math.abs(this.lat0);
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if ((Math.abs(t) - Proj4js.common.HALF_PI) < Proj4js.common.EPSLN) {
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this.mode = this.lat0 < 0. ? this.S_POLE : this.N_POLE;
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} else {
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this.mode = t > Proj4js.common.EPSLN ? this.OBLIQ : this.EQUIT;
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}
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this.phits = Math.abs(this.phits);
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if (this.es) {
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var X;
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switch (this.mode) {
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case this.N_POLE:
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case this.S_POLE:
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if (Math.abs(this.phits - Proj4js.common.HALF_PI) < Proj4js.common.EPSLN) {
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this.akm1 = 2. * this.k0 / Math.sqrt(Math.pow(1+this.e,1+this.e)*Math.pow(1-this.e,1-this.e));
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} else {
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t = Math.sin(this.phits);
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this.akm1 = Math.cos(this.phits) / Proj4js.common.tsfnz(this.e, this.phits, t);
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t *= this.e;
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this.akm1 /= Math.sqrt(1. - t * t);
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}
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break;
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case this.EQUIT:
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this.akm1 = 2. * this.k0;
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break;
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case this.OBLIQ:
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t = Math.sin(this.lat0);
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X = 2. * Math.atan(this.ssfn_(this.lat0, t, this.e)) - Proj4js.common.HALF_PI;
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t *= this.e;
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this.akm1 = 2. * this.k0 * Math.cos(this.lat0) / Math.sqrt(1. - t * t);
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this.sinX1 = Math.sin(X);
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this.cosX1 = Math.cos(X);
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break;
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}
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} else {
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switch (this.mode) {
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case this.OBLIQ:
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this.sinph0 = Math.sin(this.lat0);
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this.cosph0 = Math.cos(this.lat0);
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case this.EQUIT:
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this.akm1 = 2. * this.k0;
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break;
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case this.S_POLE:
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case this.N_POLE:
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this.akm1 = Math.abs(this.phits - Proj4js.common.HALF_PI) >= Proj4js.common.EPSLN ?
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Math.cos(this.phits) / Math.tan(Proj4js.common.FORTPI - .5 * this.phits) :
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2. * this.k0 ;
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break;
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}
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}
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},
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// Stereographic forward equations--mapping lat,long to x,y
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forward: function(p) {
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var lon = p.x;
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lon = Proj4js.common.adjust_lon(lon - this.long0);
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var lat = p.y;
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var x, y;
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if (this.sphere) {
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var sinphi, cosphi, coslam, sinlam;
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sinphi = Math.sin(lat);
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cosphi = Math.cos(lat);
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coslam = Math.cos(lon);
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sinlam = Math.sin(lon);
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switch (this.mode) {
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case this.EQUIT:
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y = 1. + cosphi * coslam;
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if (y <= Proj4js.common.EPSLN) {
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Proj4js.reportError("stere:forward:Equit");
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}
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y = this.akm1 / y;
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x = y * cosphi * sinlam;
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y *= sinphi;
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break;
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case this.OBLIQ:
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y = 1. + this.sinph0 * sinphi + this.cosph0 * cosphi * coslam;
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if (y <= Proj4js.common.EPSLN) {
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Proj4js.reportError("stere:forward:Obliq");
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}
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y = this.akm1 / y;
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x = y * cosphi * sinlam;
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y *= this.cosph0 * sinphi - this.sinph0 * cosphi * coslam;
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break;
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case this.N_POLE:
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coslam = -coslam;
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lat = -lat;
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//Note no break here so it conitnues through S_POLE
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case this.S_POLE:
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if (Math.abs(lat - Proj4js.common.HALF_PI) < this.TOL) {
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Proj4js.reportError("stere:forward:S_POLE");
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}
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y = this.akm1 * Math.tan(Proj4js.common.FORTPI + .5 * lat);
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x = sinlam * y;
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y *= coslam;
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break;
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}
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} else {
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coslam = Math.cos(lon);
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sinlam = Math.sin(lon);
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sinphi = Math.sin(lat);
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var sinX, cosX;
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if (this.mode == this.OBLIQ || this.mode == this.EQUIT) {
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var Xt = 2. * Math.atan(this.ssfn_(lat, sinphi, this.e));
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sinX = Math.sin(Xt - Proj4js.common.HALF_PI);
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cosX = Math.cos(Xt);
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}
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switch (this.mode) {
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case this.OBLIQ:
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var A = this.akm1 / (this.cosX1 * (1. + this.sinX1 * sinX + this.cosX1 * cosX * coslam));
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y = A * (this.cosX1 * sinX - this.sinX1 * cosX * coslam);
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x = A * cosX;
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break;
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case this.EQUIT:
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var A = 2. * this.akm1 / (1. + cosX * coslam);
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y = A * sinX;
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x = A * cosX;
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break;
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case this.S_POLE:
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lat = -lat;
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coslam = - coslam;
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sinphi = -sinphi;
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case this.N_POLE:
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x = this.akm1 * Proj4js.common.tsfnz(this.e, lat, sinphi);
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y = - x * coslam;
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break;
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}
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x = x * sinlam;
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}
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p.x = x*this.a + this.x0;
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p.y = y*this.a + this.y0;
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return p;
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},
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//* Stereographic inverse equations--mapping x,y to lat/long
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inverse: function(p) {
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var x = (p.x - this.x0)/this.a; /* descale and de-offset */
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var y = (p.y - this.y0)/this.a;
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var lon, lat;
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var cosphi, sinphi, tp=0.0, phi_l=0.0, rho, halfe=0.0, pi2=0.0;
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var i;
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if (this.sphere) {
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var c, rh, sinc, cosc;
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rh = Math.sqrt(x*x + y*y);
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c = 2. * Math.atan(rh / this.akm1);
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sinc = Math.sin(c);
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cosc = Math.cos(c);
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lon = 0.;
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switch (this.mode) {
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case this.EQUIT:
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if (Math.abs(rh) <= Proj4js.common.EPSLN) {
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lat = 0.;
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} else {
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lat = Math.asin(y * sinc / rh);
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}
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if (cosc != 0. || x != 0.) lon = Math.atan2(x * sinc, cosc * rh);
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break;
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case this.OBLIQ:
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if (Math.abs(rh) <= Proj4js.common.EPSLN) {
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lat = this.phi0;
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} else {
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lat = Math.asin(cosc * this.sinph0 + y * sinc * this.cosph0 / rh);
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}
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c = cosc - this.sinph0 * Math.sin(lat);
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if (c != 0. || x != 0.) {
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lon = Math.atan2(x * sinc * this.cosph0, c * rh);
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}
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break;
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case this.N_POLE:
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y = -y;
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case this.S_POLE:
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if (Math.abs(rh) <= Proj4js.common.EPSLN) {
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lat = this.phi0;
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} else {
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lat = Math.asin(this.mode == this.S_POLE ? -cosc : cosc);
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}
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lon = (x == 0. && y == 0.) ? 0. : Math.atan2(x, y);
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break;
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}
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p.x = Proj4js.common.adjust_lon(lon + this.long0);
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p.y = lat;
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} else {
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rho = Math.sqrt(x*x + y*y);
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switch (this.mode) {
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case this.OBLIQ:
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case this.EQUIT:
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tp = 2. * Math.atan2(rho * this.cosX1 , this.akm1);
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cosphi = Math.cos(tp);
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sinphi = Math.sin(tp);
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if( rho == 0.0 ) {
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phi_l = Math.asin(cosphi * this.sinX1);
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} else {
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phi_l = Math.asin(cosphi * this.sinX1 + (y * sinphi * this.cosX1 / rho));
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}
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tp = Math.tan(.5 * (Proj4js.common.HALF_PI + phi_l));
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x *= sinphi;
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y = rho * this.cosX1 * cosphi - y * this.sinX1* sinphi;
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pi2 = Proj4js.common.HALF_PI;
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halfe = .5 * this.e;
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break;
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case this.N_POLE:
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y = -y;
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case this.S_POLE:
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tp = - rho / this.akm1;
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phi_l = Proj4js.common.HALF_PI - 2. * Math.atan(tp);
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pi2 = -Proj4js.common.HALF_PI;
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halfe = -.5 * this.e;
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break;
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}
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for (i = this.NITER; i--; phi_l = lat) { //check this
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sinphi = this.e * Math.sin(phi_l);
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lat = 2. * Math.atan(tp * Math.pow((1.+sinphi)/(1.-sinphi), halfe)) - pi2;
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if (Math.abs(phi_l - lat) < this.CONV) {
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if (this.mode == this.S_POLE) lat = -lat;
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lon = (x == 0. && y == 0.) ? 0. : Math.atan2(x, y);
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p.x = Proj4js.common.adjust_lon(lon + this.long0);
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p.y = lat;
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return p;
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}
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}
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}
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}
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};
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