60 lines
1.8 KiB
JavaScript
60 lines
1.8 KiB
JavaScript
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import * as Cesium from 'cesium'
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// id generator
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export function uid(prefix) {
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const p = prefix || 'id'
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return p + ':' + Date.now().toString(36) + '_' + Math.random().toString(36).slice(2, 7)
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}
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// angle helpers
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export const toRad = Cesium.Math.toRadians
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// color normalization
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export function toCesiumColor(input, alpha) {
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const a = typeof alpha === 'number' ? alpha : 1
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if (!input) return Cesium.Color.WHITE.withAlpha(a)
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if (input instanceof Cesium.Color) return input.withAlpha(a)
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if (typeof input === 'string') return Cesium.Color.fromCssColorString(input).withAlpha(a)
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if (Array.isArray(input)) {
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const r = input[0] || 1,
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g = input[1] || 1,
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b = input[2] || 1,
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al = input[3] || a
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return new Cesium.Color(r, g, b, al)
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}
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return Cesium.Color.WHITE.withAlpha(a)
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}
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// coordinate conversions
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export function degToCartesian(arr) {
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return Cesium.Cartesian3.fromDegrees(arr[0], arr[1], arr[2] || 0)
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}
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export function degsToCartesians(positions) {
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return (positions || []).map(degToCartesian)
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}
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export function cartesianToDegrees(cartesian) {
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const c = Cesium.Cartographic.fromCartesian(cartesian)
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return {
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lon: Cesium.Math.toDegrees(c.longitude),
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lat: Cesium.Math.toDegrees(c.latitude),
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height: c.height || 0,
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}
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}
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// simple zoom-height heuristic
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const EARTH = 40075016.68557849
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const TILE = 256
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export function heightToZoom(height, lat) {
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const la = typeof lat === 'number' ? lat : 0
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const z = Math.log2((EARTH * Math.cos(toRad(la))) / (TILE * Math.max(height || 1, 1))) + 8
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return Math.max(0, z)
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}
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export function zoomToHeight(zoom, lat) {
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const la = typeof lat === 'number' ? lat : 0
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const h = (EARTH * Math.cos(toRad(la))) / (TILE * Math.pow(2, Math.max((zoom || 0) - 8, 0)))
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return Math.max(1, h)
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}
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export const DEFAULT_VECTOR_LAYER_ID = 'vector:default'
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