49 lines
1.0 KiB
JavaScript
49 lines
1.0 KiB
JavaScript
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import adjust_lon from '../common/adjust_lon';
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export function init() {
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this.x0 = this.x0 || 0;
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this.y0 = this.y0 || 0;
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this.lat0 = this.lat0 || 0;
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this.long0 = this.long0 || 0;
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///this.t2;
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}
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/* Equirectangular forward equations--mapping lat,long to x,y
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---------------------------------------------------------*/
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export function forward(p) {
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var lon = p.x;
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var lat = p.y;
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var dlon = adjust_lon(lon - this.long0);
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var x = this.x0 + this.a * dlon * Math.cos(this.lat0);
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var y = this.y0 + this.a * lat;
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this.t1 = x;
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this.t2 = Math.cos(this.lat0);
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p.x = x;
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p.y = y;
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return p;
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}
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/* Equirectangular inverse equations--mapping x,y to lat/long
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---------------------------------------------------------*/
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export function inverse(p) {
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p.x -= this.x0;
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p.y -= this.y0;
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var lat = p.y / this.a;
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var lon = adjust_lon(this.long0 + p.x / (this.a * Math.cos(this.lat0)));
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p.x = lon;
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p.y = lat;
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}
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export var names = ["equi"];
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export default {
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init: init,
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forward: forward,
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inverse: inverse,
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names: names
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};
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