61 lines
2.4 KiB
JavaScript
61 lines
2.4 KiB
JavaScript
/* *
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* Lambert Conformal Conic projection
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* */
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'use strict';
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var sign = Math.sign ||
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(function (n) { return (n === 0 ? 0 : n > 0 ? 1 : -1); }), scale = 63.78137, deg2rad = Math.PI / 180, halfPI = Math.PI / 2, eps10 = 1e-6, tany = function (y) { return Math.tan((halfPI + y) / 2); };
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var LambertConformalConic = /** @class */ (function () {
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function LambertConformalConic(options) {
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var _a;
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var parallels = (options.parallels || [])
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.map(function (n) { return n * deg2rad; }), lat1 = parallels[0] || 0, lat2 = (_a = parallels[1]) !== null && _a !== void 0 ? _a : lat1, cosLat1 = Math.cos(lat1);
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if (typeof options.projectedBounds === 'object') {
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this.projectedBounds = options.projectedBounds;
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}
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// Apply the global variables
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var n = lat1 === lat2 ?
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Math.sin(lat1) :
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Math.log(cosLat1 / Math.cos(lat2)) / Math.log(tany(lat2) / tany(lat1));
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if (Math.abs(n) < 1e-10) {
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n = (sign(n) || 1) * 1e-10;
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}
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this.n = n;
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this.c = cosLat1 * Math.pow(tany(lat1), n) / n;
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}
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LambertConformalConic.prototype.forward = function (lonLat) {
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var lon = lonLat[0] * deg2rad, _a = this, c = _a.c, n = _a.n, projectedBounds = _a.projectedBounds;
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var lat = lonLat[1] * deg2rad;
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if (c > 0) {
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if (lat < -halfPI + eps10) {
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lat = -halfPI + eps10;
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}
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}
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else {
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if (lat > halfPI - eps10) {
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lat = halfPI - eps10;
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}
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}
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var r = c / Math.pow(tany(lat), n), x = r * Math.sin(n * lon) * scale, y = (c - r * Math.cos(n * lon)) * scale, xy = [x, y];
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if (projectedBounds && (x < projectedBounds.x1 ||
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x > projectedBounds.x2 ||
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y < projectedBounds.y1 ||
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y > projectedBounds.y2)) {
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xy.outside = true;
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}
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return xy;
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};
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LambertConformalConic.prototype.inverse = function (xy) {
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var x = xy[0] / scale, y = xy[1] / scale, _a = this, c = _a.c, n = _a.n, cy = c - y, rho = sign(n) * Math.sqrt(x * x + cy * cy);
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var l = Math.atan2(x, Math.abs(cy)) * sign(cy);
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if (cy * n < 0) {
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l -= Math.PI * sign(x) * sign(cy);
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}
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return [
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(l / n) / deg2rad,
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(2 * Math.atan(Math.pow(c / rho, 1 / n)) - halfPI) / deg2rad
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];
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};
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return LambertConformalConic;
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}());
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export default LambertConformalConic;
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