44 lines
1.1 KiB
JavaScript
44 lines
1.1 KiB
JavaScript
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import Projection from './projection.js'
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/**
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* This is a projection file, that grants access to the
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* MERCATOR projection.
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*
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* Regulary only few Projections will be used in one
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* project, therefore only required one's should be
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* loaded.
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*/
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export default class Mercator extends Projection {
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forward(coords) {
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let lat = coords.x
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let lng = coords.y
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const PI_180 = Math.PI / 180.0
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const PI_4 = Math.PI * 4
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const sinLatitude = Math.sin(lat * PI_180)
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let y = 0.5 - Math.log((1 + sinLatitude) / (1 - sinLatitude)) / PI_4
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let x = (lng + 180) / 360
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y = y < 0 ? 0 : y > 1 ? 1 : y
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return new PIXI.Point(x, y)
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}
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backward(point) {
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let lng = point.x * 360 - 180
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let lat = (Math.asin(-2 / (Math.exp(4 * Math.PI * (0.5 - point.y)) + 1) + 1) * 180) / Math.PI
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return new PIXI.Point(lat, lng)
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}
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toString() {
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return 'Mercator Projection'
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}
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get maxViewport() {
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return { min: new PIXI.Point(-85, -180), max: new PIXI.Point(85, 180) }
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}
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}
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