245 lines
8.3 KiB
JavaScript
245 lines
8.3 KiB
JavaScript
// import * as mars3d from "mars3d"
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// const Cesium = mars3d.Cesium
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// 按mars3d规范，封装的pbf图层
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;(function (window) {
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const BasicRenderer = window.mapboxRenderer.BasicRenderer
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// 创建一个全局变量作为pbfBasicRenderer渲染模板，避免出现16个canvas上下文的浏览器限制，以便Cesium ImageLayer.destory()正常工作。
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// https://github.com/mapbox/mapbox-gl-js/issues/7332
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const OFFSCREEN_CANV_SIZE = 1024
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const baseCanv = document.createElement("canvas")
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baseCanv.style.imageRendering = "pixelated"
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baseCanv.addEventListener("webglcontextlost", () => console.log("webglcontextlost"), false)
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baseCanv.width = OFFSCREEN_CANV_SIZE
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baseCanv.height = OFFSCREEN_CANV_SIZE
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class MVTImageryProvider {
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/**
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*
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* @param {Object} options
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* @param {Object} options.style - mapbox style object
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* @param {Function} [options.sourceFilter] - sourceFilter is used to filter which source participate in pickFeature process.
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* @param {Number} [options.maximumLevel] - if cesium zoom level exceeds maximumLevel, layer will be invisible.
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* @param {Number} [options.minimumLevel] - if cesium zoom level belows minimumLevel, layer will be invisible.
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* @param {Number} [options.tileSize=512] - can be 256 or 512.
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* @param {Boolean} [options.hasAlphaChannel] -
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* @param {String} [options.credit] -
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*
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*/
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constructor(options) {
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this.options = options
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let pbfStyle = options.style
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this.mapboxRenderer = new BasicRenderer({
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style: pbfStyle
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})
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this.mapboxRenderer._transformRequest = (url, resourceType) => {
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return this.transformRequest(url, resourceType)
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}
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this.mapboxRenderer._canvas = baseCanv
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this.mapboxRenderer._canvas.addEventListener("webglcontextrestored", () => this.mapboxRenderer._createGlContext(), false)
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this.mapboxRenderer._createGlContext()
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if (options.showCanvas) {
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this.mapboxRenderer.showCanvasForDebug()
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}
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this.ready = false
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this.readyPromise = this.mapboxRenderer._style.loadedPromise.then(() => {
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this.ready = true
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})
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this.tilingScheme = options.tilingScheme ?? new Cesium.WebMercatorTilingScheme()
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this.rectangle = this.tilingScheme.rectangle
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this.tileSize = this.tileWidth = this.tileHeight = options.tileSize || 512
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this.maximumLevel = options.maximumLevel || Number.MAX_SAFE_INTEGER
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this.minimumLevel = options.minimumLevel || 0
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this.tileDiscardPolicy = undefined
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this.errorEvent = new Cesium.Event()
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this.credit = new Cesium.Credit(options.credit || "", false)
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this.proxy = new Cesium.DefaultProxy("")
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this.hasAlphaChannel = options.hasAlphaChannel ?? true
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this.sourceFilter = options.sourceFilter
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}
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transformRequest = (url) => {
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if (this.options.transformUrl) {
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url = this.options.transformUrl(url)
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}
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return { url: url, headers: this.options.headers || {}, credentials: "" }
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}
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getTileCredits(x, y, level) {
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return []
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}
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createTile() {
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const canv = document.createElement("canvas")
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canv.width = this.tileSize
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canv.height = this.tileSize
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canv.style.imageRendering = "pixelated"
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const ctx = canv.getContext("2d")
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if (ctx) {
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ctx.globalCompositeOperation = "copy"
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}
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return canv
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}
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_getTilesSpec(coord, source) {
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const { x, y, zoom } = coord
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const TILE_SIZE = this.tileSize
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// 3x3 grid of source tiles, where the region of interest is that corresponding to the central source tile
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const ret = []
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const maxTile = (1 << zoom) - 1
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for (let xx = -1; xx <= 1; xx++) {
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let newx = x + xx
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if (newx < 0) {
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newx = maxTile
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}
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if (newx > maxTile) {
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newx = 0
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}
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for (let yy = -1; yy <= 1; yy++) {
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const newy = y + yy
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if (newy < 0) {
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continue
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}
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if (newy > maxTile) {
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continue
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}
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ret.push({
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source: source,
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z: zoom,
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x: newx,
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y: newy,
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left: 0 + xx * TILE_SIZE,
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top: 0 + yy * TILE_SIZE,
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size: TILE_SIZE
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})
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}
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}
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return ret
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}
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requestImage(x, y, zoom, releaseTile = true) {
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if (zoom > this.maximumLevel || zoom < this.minimumLevel) {
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return Promise.reject(undefined)
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}
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this.mapboxRenderer.filterForZoom(zoom)
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const tilesSpec = this.mapboxRenderer.getVisibleSources().reduce((a, s) => a.concat(this._getTilesSpec({ x, y, zoom }, s)), [])
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return new Promise((resolve, reject) => {
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const canv = this.createTile()
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const ctx = canv.getContext("2d")
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const renderRef = this.mapboxRenderer.renderTiles(
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ctx,
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{
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srcLeft: 0,
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srcTop: 0,
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width: this.tileSize,
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height: this.tileSize,
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destLeft: 0,
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destTop: 0
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},
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tilesSpec,
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(err) => {
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/**
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* In case of err ends with 'tiles not available', the canvas will still be painted.
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* relate url: https://github.com/landtechnologies/Mapbox-vector-tiles-basic-js-renderer/blob/master/src/basic/renderer.js#L341-L405
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*/
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if (typeof err === "string" && !err.endsWith("tiles not available")) {
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reject(undefined)
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} else if (releaseTile) {
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renderRef.consumer.ctx = undefined
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resolve(canv)
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// releaseTile默认为true，对应Cesium请求图像的情形
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this.mapboxRenderer.releaseRender(renderRef)
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this.mapboxRenderer._style.sourceCaches?.origin?._tileCache.reset()
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} else {
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// releaseTile为false时在由pickFeature手动调用，在渲染完成之后在pickFeature里边手动释放tile
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resolve(renderRef)
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}
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}
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)
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})
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}
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pickFeatures(x, y, zoom, longitude, latitude) {
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return this.requestImage(x, y, zoom, false).then((renderRef) => {
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let targetSources = this.mapboxRenderer.getVisibleSources(zoom)
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targetSources = this.sourceFilter ? this.sourceFilter(targetSources) : targetSources
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const queryResult = []
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longitude = Cesium.Math.toDegrees(longitude)
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latitude = Cesium.Math.toDegrees(latitude)
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targetSources.forEach((s) => {
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const data = this.mapboxRenderer.queryRenderedFeatures({
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source: s,
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renderedZoom: zoom,
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lng: longitude,
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lat: latitude,
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tileZ: zoom
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})
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for (const key in data) {
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const item = data[key]
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for (let index = 0; index < item.length; index++) {
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const element = item[index]
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element.layer = key
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queryResult.push({ properties: element })
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}
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}
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})
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// release tile
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renderRef.consumer.ctx = undefined
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this.mapboxRenderer.releaseRender(renderRef)
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this.mapboxRenderer._style.sourceCaches?.origin?._tileCache.reset()
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return queryResult
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})
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}
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destroy() {
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this.mapboxRenderer._cancelAllPendingRenders()
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Object.values(this.mapboxRenderer._style.sourceCaches).forEach((cache) => cache._tileCache.reset())
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this.mapboxRenderer._gl.getExtension("WEBGL_lose_context").loseContext()
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}
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}
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class PbfLayer extends mars3d.layer.BaseTileLayer {
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// 构建ImageryProvider
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async _createImageryProvider(options) {
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return createImageryProvider(options)
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}
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}
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async function createImageryProvider(options) {
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if (options.url) {
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let data = await Cesium.Resource.fetchJson(options)
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const provider = new MVTImageryProvider({ ...options, style: data })
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await provider.readyPromise
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return provider
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} else {
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const provider = new MVTImageryProvider(options)
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await provider.readyPromise
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return provider
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}
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}
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PbfLayer.createImageryProvider = createImageryProvider
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// 注册下
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const layerType = "pbf" // 图层类型
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mars3d.LayerUtil.register(layerType, PbfLayer)
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mars3d.LayerUtil.registerImageryProvider(layerType, createImageryProvider)
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// 对外接口
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window.mars3d.layer.PbfLayer = PbfLayer
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})(window)
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// export { PbfLayer }
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