一、根据点跟角度计算另一点坐标（三维球体）
export const getAnotherPoint = (lon: number, lat: number, angle: number, distance: number) => {// WGS84坐标系var a = 6378137; // 赤道半径var b = 6356752.3142; // 短半径var f = 1 / 298.257223563; // 扁率var alpha1 = angle * (Math.PI / 180)var sinAlpha1 = Math.sin(alpha1);var cosAlpha1 = Math.cos(alpha1);var tanU1 = (1 - f) * Math.tan(lat * (Math.PI / 180));var cosU1 = 1 / Math.sqrt((1 + tanU1 * tanU1)), sinU1 = tanU1 * cosU1;var sigma1 = Math.atan2(tanU1, cosAlpha1);var sinAlpha = cosU1 * sinAlpha1;var cosSqAlpha = 1 - sinAlpha * sinAlpha;var uSq = cosSqAlpha * (a * a - b * b) / (b * b);var A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));var B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));var sigma = distance / (b * A), sigmaP = 2 * Math.PI;let sinSigma = 0let cosSigma = 0let cos2SigmaM = 0while (Math.abs(sigma - sigmaP) > 1e-12) {cos2SigmaM = Math.cos(2 * sigma1 + sigma);sinSigma = Math.sin(sigma);cosSigma = Math.cos(sigma);var deltaSigma = B * sinSigma * (cos2SigmaM + B / 4 * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) -B / 6 * cos2SigmaM * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)));sigmaP = sigma;sigma = distance / (b * A) + deltaSigma;}var tmp = sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1;var lat2 = Math.atan2(sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1,(1 - f) * Math.sqrt(sinAlpha * sinAlpha + tmp * tmp));var lambda = Math.atan2(sinSigma * sinAlpha1, cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1);var C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha));var L = lambda - (1 - C) * f * sinAlpha *(sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)));return { lon: Number(lon) + L * (180 / Math.PI), lat: lat2 * (180 / Math.PI) };
}
二、渐变材质
export const getMaterial = () => {let appearance = new Cesium.MaterialAppearance({vertexShaderSource: `attribute vec3 position3DHigh; attribute vec3 position3DLow;attribute float batchId;varying vec4 v_positionEC;attribute vec4 color;varying vec4 v_color;void main(){v_color = color;vec4 p = czm_computePosition(); // 获取模型相对于视点位置vec4 eyePosition = czm_modelViewRelativeToEye * p; // 由模型坐标 得到视点坐标v_positionEC = czm_inverseModelView * eyePosition; // 视点在 模型坐标系中的位置gl_Position = czm_modelViewProjectionRelativeToEye * p; // 视点坐标转为屏幕坐标}`,fragmentShaderSource: ` varying vec4 v_positionEC;varying vec3 v_normalEC;varying vec4 v_color;void main() {float l = sqrt(pow(v_positionEC.x,2.0) + pow(v_positionEC.y,2.0) + pow(v_positionEC.z,2.0)); // 距离模型坐标系原点的距离float cy3 = fract((abs(l-27.0))/40.0); // 修改渐变方向 float cy3 = 1- fract((abs(l-27.0))/40.0); gl_FragColor = vec4(v_color.rgb,cy3);}`,})return appearance
}
三、根据两点坐标获取偏航角和俯仰角
function getHeadingPitch(fromPosition, toPosition) {let finalPosition = new Cesium.Cartesian3();let matrix4 = Cesium.Transforms.eastNorthUpToFixedFrame(fromPosition);Cesium.Matrix4.inverse(matrix4, matrix4);Cesium.Matrix4.multiplyByPoint(matrix4, toPosition, finalPosition);Cesium.Cartesian3.normalize(finalPosition, finalPosition);const resultHead = Cesium.Math.toDegrees(Math.atan2(finalPosition.x, finalPosition.y))const resultPitch = Cesium.Math.toDegrees(Math.asin(finalPosition.z))return {resultHead ,resultPitch };
}
四、添加实体
（一）点
//entities.add(entity)
viewer.entities.add({// fromDegrees（经度，纬度，高度，椭球，结果）从以度为单位的经度和纬度值返回Cartesian3位置position: Cesium.Cartesian3.fromDegrees(108, 34, 10),point: {// 点的大小（像素）pixelSize: 5,// 点位颜色，fromCssColorString 可以直接使用CSS颜色color: Cesium.Color.fromCssColorString('#ee0000'),// 边框颜色outlineColor: Cesium.Color.fromCssColorString('#fff'),// 边框宽度(像素)outlineWidth: 2,// 显示在距相机的距离处的属性，多少区间内是可以显示的distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 1500),// 是否显示show: true}});
（二）线
viewer.entities.add({polyline: {// fromDegrees返回给定的经度和纬度值数组（以度为单位），该数组由Cartesian3位置组成。// Cesium.Cartesian3.fromDegreesArray([经度1, 纬度1, 经度2, 纬度2,])// Cesium.Cartesian3.fromDegreesArrayHeights([经度1, 纬度1, 高度1, 经度2, 纬度2, 高度2])positions: Cesium.Cartesian3.fromDegreesArray([120.9677706, 30.7985748,110.20, 34.55]),// 宽度width: 2,// 线的颜色material: Cesium.Color.WHITE,// 线的顺序,仅当`clampToGround`为true并且支持地形上的折线时才有效。zIndex: 10,// 显示在距相机的距离处的属性，多少区间内是可以显示的distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 1500),// 是否显示show: true}});
（三）面
viewer.entities.add({polygon: {// 获取指定属性（positions，holes（图形内需要挖空的区域））hierarchy: {positions: Cesium.Cartesian3.fromDegreesArray([120.9677706, 30.7985748,110.20, 34.55,120.20, 50.55]),holes: [{positions: Cesium.Cartesian3.fromDegreesArray([119, 32,115, 34,119, 40])}]},// 边框outline: true,// 边框颜色outlineColor: Cesium.Color.WHITE,// 边框尺寸outlineWidth: 2,// 填充的颜色，withAlpha透明度material: Cesium.Color.GREEN.withAlpha(0.5),// 是否被提供的材质填充fill: true,// 恒定高度height: 5000,// 显示在距相机的距离处的属性，多少区间内是可以显示的distanceDisplayCondition: new Cesium.DistanceDisplayCondition(1000, 10000000),// 是否显示show: true,// 顺序,仅当`clampToGround`为true并且支持地形上的折线时才有效。zIndex: 10}});
（四）文字
viewer.entities.add({position: Cesium.Cartesian3.fromDegrees(120, 30, 5),// 点point: {color: Cesium.Color.RED, // 点位颜色pixelSize: 10 // 像素点大小},// 文字label: {// 文本。支持显式换行符“ \ n”text: '测试名称',// 字体样式，以CSS语法指定字体font: '14pt Source Han Sans CN',// 字体颜色fillColor: Cesium.Color.BLACK,// 背景颜色backgroundColor: Cesium.Color.AQUA,// 是否显示背景颜色showBackground: true,// 字体边框outline: true,// 字体边框颜色outlineColor: Cesium.Color.WHITE,// 字体边框尺寸outlineWidth: 10,// 应用于图像的统一比例。比例大于会1.0放大标签，而比例小于会1.0缩小标签。scale: 1.0,// 设置样式：FILL：填写标签的文本，但不要勾勒轮廓；OUTLINE：概述标签的文本，但不要填写；FILL_AND_OUTLINE：填写并概述标签文本。style: Cesium.LabelStyle.FILL_AND_OUTLINE,// 相对于坐标的水平位置verticalOrigin: Cesium.VerticalOrigin.CENTER,// 相对于坐标的水平位置horizontalOrigin: Cesium.HorizontalOrigin.LEFT,// 该属性指定标签在屏幕空间中距此标签原点的像素偏移量pixelOffset: new Cesium.Cartesian2(10, 0),// 显示在距相机的距离处的属性，多少区间内是可以显示的distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 1500),// 是否显示show: true}});
（五）广告牌（图片）
viewer.entities.add({position: Cesium.Cartesian3.fromDegrees(110.20, 34.55, 2.61),billboard: {// 图像地址，URI或Canvas的属性image: '/location.png',// 设置颜色和透明度color: Cesium.Color.WHITE.withAlpha(0.8),// 高度（以像素为单位）height: 50,// 宽度（以像素为单位）width: 50,// 逆时针旋转rotation: 20,// 大小是否以米为单位sizeInMeters: false,// 相对于坐标的垂直位置verticalOrigin: Cesium.VerticalOrigin.CENTER,// 相对于坐标的水平位置horizontalOrigin: Cesium.HorizontalOrigin.LEFT,// 该属性指定标签在屏幕空间中距此标签原点的像素偏移量pixelOffset: new Cesium.Cartesian2(10, 0),// 应用于图像的统一比例。比例大于会1.0放大标签，而比例小于会1.0缩小标签。scale: 1.0,// 显示在距相机的距离处的属性，多少区间内是可以显示的distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 1500),// 是否显示show: true}
});
（六）模型
viewer.entities.add({// 设置方向orientation: orientation,position: Cesium.Cartesian3.fromDegrees(120, 30, 10000),model: {// 引入模型uri: '/SampleData/models/CesiumAir/Cesium_Air.glb',// 模型的近似最小像素大小，而不考虑缩放。这可以用来确保即使观看者缩小也可以看到模型。如果为0.0，则不强制使用最小大小minimumPixelSize: 1280,// 模型的颜色（与模型的渲染颜色混合的属性）color: Cesium.Color.WHITE.withAlpha(1),// 模型的最大比例大小maximumScale: 20000,// 设置模型轮廓（边框）颜色silhouetteColor: Cesium.Color.BLACK,// 设置模型轮廓（边框）大小silhouetteSize: 2,// 是否执行模型动画runAnimations: true,// 应用于图像的统一比例。比例大于会1.0放大标签，而比例小于会1.0缩小标签。scale: 1.0,// 显示在距相机的距离处的属性，多少区间内是可以显示的distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 1500),// 是否显示show: true}});
五、添加primitive
（一）点
const pointsDataSource = viewer.scene.primitives.add(new Cesium.PointPrimitiveCollection())
// 创建点
for (const index in points) {pointsDataSource.add({pixelSize: 10,color: Cesium.Color.fromCssColorString('#fff'),position: Cesium.Cartesian3.fromDegrees(item[0], item[1], item[2]),});
}
// 销毁点
pointsDataSource?.removeAll();
（二）线
const newArr1 = []; let newArr2 = [];
// eslint-disable-next-line array-callback-return
points.map((item) => {newArr1.push(item[0]);newArr1.push(item[1]);newArr1.push(item[2]);
});
newArr2 = newArr1;
/// map原由fromDegreesArray 所需的数据属于[lon, lat, height, lon, lat, height, ...]
/// 所以需要map改造/// 创建线
const lineDataSource = viewer.scene.primitives.add(new Cesium.PolylineCollection());
lineDataSource.add({width: 2,positions: this.Cesium.Cartesian3.fromDegreesArrayHeights(newArr2),material: this.Cesium.Material.fromType('Color', {color: this.Cesium.Color.fromCssColorString('#EADDCA'),}),
});/// 销毁线
lineDataSource?.removeAll();
（三）广告牌
billboards.add({position: Cesium.Cartesian3.fromDegrees(item[0], item[1], item[2]),image: '图片地址', // image:pinBuilder.fromColor(Cesium.Color.fromRandom({ alpha: 1.0 }), 20).toDataURL()width: 18,height: 18,verticalOrigin: Cesium.VerticalOrigin.BOTTOM,})
加载大量贴地广告牌：BillboardCollection
const collection = new Cesium.BillboardCollection({ scene: viewer.scene })
1、heightReference属性
collection.add({position: position,image: pinBuilder.fromColor(Cesium.Color.fromRandom({ alpha: 1.0 }), 20).toDataURL(),verticalOrigin: Cesium.VerticalOrigin.BOTTOM,horizontalOrigin: Cesium.HorizontalOrigin.CENTER,heightReference: Cesium.HeightReference.CLAMP_TO_GROUND
})
2、sampleTerrainMostDetailed方法
// 1、生成大量随机点
const points = randomPoint(500, { bbox: [100, 25, 102, 27] })
// 2、Cartographic数组
const positions = []
for (let point of points.features) {const coordinates = point.geometry.coordinatesconst position = Cesium.Cartographic.fromDegrees(coordinates[0], coordinates[1])positions.push(position)
}
// 3、高程采样
const pinBuilder = new Cesium.PinBuilder();
const collection = new Cesium.BillboardCollection()
const terrainProvider = viewer.terrainProvider
const promise = Cesium.sampleTerrainMostDetailed(terrainProvider, positions);
Promise.resolve(promise).then(function (updatedPositions) {for (let position of updatedPositions) {collection.add({position: Cesium.Cartesian3.fromRadians(position.longitude, position.latitude, position.height),image: pinBuilder.fromColor(Cesium.Color.fromRandom({ alpha: 1.0 }), 20).toDataURL(),verticalOrigin: Cesium.VerticalOrigin.BOTTOM,horizontalOrigin: Cesium.HorizontalOrigin.CENTER,})}viewer.scene.primitives.add(collection)
});
（四）标注
labels.add({position: Cesium.Cartesian3.fromDegrees(item[0], item[1], item[2]),text: `文字标注`,font: '10px sans-serif',
});
（五）几何图形
以折线和多边形为例：
let rectangleInstanceArr = [];//定义折线几何let polyline = new Cesium.PolylineGeometry({positions: Cesium.Cartesian3.fromDegreesArray([119.7,30.2,119.8,30.2,119.85,30.3]),width: 10.0,vertexFormat:Cesium.PolylineColorAppearance.VERTEX_FORMAT});//定义多边形几何// let polygon = new Cesium.PolygonGeometry({// polygonHierarchy: new Cesium.PolygonHierarchy(// Cesium.Cartesian3.fromDegreesArray([// 119.7,// 30.2,// 119.8,// 30.2,// 119.85,// 30.3,// ])// ),// vertexFormat: Cesium.PerInstanceColorAppearance.VERTEX_FORMAT,// });var rectangleInstance = new Cesium.GeometryInstance({geometry: polyline,attributes: {color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.RED),},});rectangleInstanceArr.push(rectangleInstance);this.viewer.scene.primitives.add(new Cesium.Primitive({geometryInstances: rectangleInstanceArr,//多边形外观// appearance: new Cesium.PerInstanceColorAppearance({// translucent: true,// closed: false,// }),//折线外观appearance:new Cesium.PolylineColorAppearance({translucent:false}),asynchronous: false,}));
六、定位
（一）定位到点
1、viewer
let entity = null;
/*** 视图定位方法，定位到点* @param lon 经度* @param lat 纬度* @param alt 范围（相机距离中心点的位置为5000）*/
function viewerFlyToLonLat(lon, lat, alt) {entity && viewer.entities.remove(entity);entity = new Cesium.Entity({id: 'flyTojwd',position: Cesium.Cartesian3.fromDegrees(lon, lat),point: {pixelSize: 10,color: Cesium.Color.WHITE.withAlpha(0.9),outlineColor: Cesium.Color.WHITE.withAlpha(0.9),outlineWidth: 1}});viewer.entities.add(entity);viewer.flyTo(entity, {offset: {heading: Cesium.Math.toRadians(0.0), //默认方向为正北，正角度为向东旋转，即水平选装，也叫偏航角pitch: Cesium.Math.toRadians(-50), // 俯仰角range: alt}});
}
2、camera
/**
* 相机定位方法，定位到点
* @param lon 经度
* @param lat 纬度
* @param alt 范围（相机距离中心点的位置为5000）
*/
function cameraFlyToLonLat(lon, lat, alt) {viewer.camera.flyTo({destination: Cesium.Cartesian3.fromDegrees(lon, lat, alt),orientation: {heading: Cesium.Math.toRadians(0.0),pitch: Cesium.Math.toRadians(-25.0),roll: 0.0}});
}
（二）定位到范围
1、viewer
/*** 视图定位方法，定位到范围* @param rect 范围数组（最西、最南、最东、最北）*/
function viewerFlyToRange(rect) {if (locationRectEntity)viewer.entities.remove(locationRectEntity);locationRectEntity = viewer.entities.add({name: 'locationRectangle',id: 'locationRectangle',rectangle: {coordinates: Cesium.Rectangle.fromDegrees(rect[0], rect[1], rect[2], rect[3]),material: Cesium.Color.GREEN.withAlpha(1.0),height: 10.0,outline: false}});let flyPromise = viewer.flyTo(locationRectEntity, {duration: 5,offset: new Cesium.HeadingPitchRange(0.0, Cesium.Math.toRadians(-20.0))});
}
2、camera
/**
* 相机定位方法，定位到范围
* @param rect 范围数组（最西、最南、最东、最北）
*/
function cameraFlyToRange(rect) {viewer.camera.flyTo({destination: Cesium.Rectangle.fromDegrees(rect[0], rect[1], rect[2], rect[3]),duration: 5,orientation: {heading: Cesium.Math.toRadians(0.0),pitch: Cesium.Math.toRadians(-25.0),roll: 0.0}});
}
七、可视域分析
（一）ShadowMap
阴影贴图：new Cesium.ShadowMap (options)
Cesium用它来实现阴影效果。
ShadowMap的一个比较明显的缺点是阴影边缘锯齿化很严重，而PCF则能有效地克服Shadow Map阴影边缘的锯齿。
（二）Frustum
new Cesium.FrustumOutlineGeometry (options)：绘制视锥的轮廓线
（三）Camera
给定视锥的起点、向前的方向和向上的方向，把视锥的方向确定下来，设置了视锥的视野角度、宽高比、近平面距离和远平面距离，把视锥的形状确定下来了。
// 创建一个沿负z轴向下的，位于原点的，视野为60度的，宽高比为1:1的相机。
var camera = new Cesium.Camera(scene);
camera.position = new Cesium.Cartesian3();
camera.direction = Cesium.Cartesian3.negate(Cesium.Cartesian3.UNIT_Z, new Cesium.Cartesian3());
camera.up = Cesium.Cartesian3.clone(Cesium.Cartesian3.UNIT_Y);
camera.frustum.fov = Cesium.Math.PI_OVER_THREE;
camera.frustum.near = 1.0;
camera.frustum.far = 2.0;
（四）视网
用EllipsoidGraphics绘制的实体对象。
（五）具体实现
// ViewShed.js/*** 可视域分析。** @author Helsing* @date 2020/08/28* @alias ViewShedStage* @class* @param {Cesium.Viewer} viewer Cesium三维视窗。* @param {Object} options 选项。* @param {Cesium.Cartesian3} options.viewPosition 观测点位置。* @param {Cesium.Cartesian3} options.viewPositionEnd 最远观测点位置（如果设置了观测距离，这个属性可以不设置）。* @param {Number} options.viewDistance 观测距离（单位`米`，默认值100）。* @param {Number} options.viewHeading 航向角（单位`度`，默认值0）。* @param {Number} options.viewPitch 俯仰角（单位`度`，默认值0）。* @param {Number} options.horizontalViewAngle 可视域水平夹角（单位`度`，默认值90）。* @param {Number} options.verticalViewAngle 可视域垂直夹角（单位`度`，默认值60）。* @param {Cesium.Color} options.visibleAreaColor 可视区域颜色（默认值`绿色`）。* @param {Cesium.Color} options.invisibleAreaColor 不可视区域颜色（默认值`红色`）。* @param {Boolean} options.enabled 阴影贴图是否可用。* @param {Boolean} options.softShadows 是否启用柔和阴影。* @param {Boolean} options.size 每个阴影贴图的大小。*/
class ViewShedStage {constructor(viewer, options) {this.viewer = viewer;this.viewPosition = options.viewPosition;this.viewPositionEnd = options.viewPositionEnd;this.viewDistance = this.viewPositionEnd ? Cesium.Cartesian3.distance(this.viewPosition, this.viewPositionEnd) : (options.viewDistance || 100.0);this.viewHeading = this.viewPositionEnd ? getHeading(this.viewPosition, this.viewPositionEnd) : (options.viewHeading || 0.0);this.viewPitch = this.viewPositionEnd ? getPitch(this.viewPosition, this.viewPositionEnd) : (options.viewPitch || 0.0);this.horizontalViewAngle = options.horizontalViewAngle || 90.0;this.verticalViewAngle = options.verticalViewAngle || 60.0;this.visibleAreaColor = options.visibleAreaColor || Cesium.Color.GREEN;this.invisibleAreaColor = options.invisibleAreaColor || Cesium.Color.RED;this.enabled = (typeof options.enabled === "boolean") ? options.enabled : true;this.softShadows = (typeof options.softShadows === "boolean") ? options.softShadows : true;this.size = options.size || 2048;this.update();}add() {this.createLightCamera();this.createShadowMap();this.createPostStage();this.drawFrustumOutine();this.drawSketch();}update() {this.clear();this.add();}clear() {if (this.sketch) {this.viewer.entities.removeById(this.sketch.id);this.sketch = null;}if (this.frustumOutline) {this.frustumOutline.destroy();this.frustumOutline = null;}if (this.postStage) {this.viewer.scene.postProcessStages.remove(this.postStage);this.postStage = null;}}
}export default ViewShed;
创建相机：
createLightCamera() {this.lightCamera = new Cesium.Camera(this.viewer.scene);this.lightCamera.position = this.viewPosition;// if (this.viewPositionEnd) {// let direction = Cesium.Cartesian3.normalize(Cesium.Cartesian3.subtract(this.viewPositionEnd, this.viewPosition, new Cesium.Cartesian3()), new Cesium.Cartesian3());// this.lightCamera.direction = direction; // direction是相机面向的方向// }this.lightCamera.frustum.near = this.viewDistance * 0.001;this.lightCamera.frustum.far = this.viewDistance;const hr = Cesium.Math.toRadians(this.horizontalViewAngle);const vr = Cesium.Math.toRadians(this.verticalViewAngle);const aspectRatio =(this.viewDistance * Math.tan(hr / 2) * 2) /(this.viewDistance * Math.tan(vr / 2) * 2);this.lightCamera.frustum.aspectRatio = aspectRatio;if (hr > vr) {this.lightCamera.frustum.fov = hr;} else {this.lightCamera.frustum.fov = vr;}this.lightCamera.setView({destination: this.viewPosition,orientation: {heading: Cesium.Math.toRadians(this.viewHeading || 0),pitch: Cesium.Math.toRadians(this.viewPitch || 0),roll: 0}});
}
创建阴影贴图：
createShadowMap() {this.shadowMap = new Cesium.ShadowMap({context: (this.viewer.scene).context,lightCamera: this.lightCamera,enabled: this.enabled,isPointLight: true,pointLightRadius: this.viewDistance,cascadesEnabled: false,size: this.size,softShadows: this.softShadows,normalOffset: false,fromLightSource: false});this.viewer.scene.shadowMap = this.shadowMap;
}
创建PostStage：
createPostStage() {const fs = glslconst postStage = new Cesium.PostProcessStage({fragmentShader: fs,uniforms: {shadowMap_textureCube: () => {this.shadowMap.update(Reflect.get(this.viewer.scene, "_frameState"));return Reflect.get(this.shadowMap, "_shadowMapTexture");},shadowMap_matrix: () => {this.shadowMap.update(Reflect.get(this.viewer.scene, "_frameState"));return Reflect.get(this.shadowMap, "_shadowMapMatrix");},shadowMap_lightPositionEC: () => {this.shadowMap.update(Reflect.get(this.viewer.scene, "_frameState"));return Reflect.get(this.shadowMap, "_lightPositionEC");},shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness: () => {this.shadowMap.update(Reflect.get(this.viewer.scene, "_frameState"));const bias = this.shadowMap._pointBias;return Cesium.Cartesian4.fromElements(bias.normalOffsetScale,this.shadowMap._distance,this.shadowMap.maximumDistance,0.0,new Cesium.Cartesian4());},shadowMap_texelSizeDepthBiasAndNormalShadingSmooth: () => {this.shadowMap.update(Reflect.get(this.viewer.scene, "_frameState"));const bias = this.shadowMap._pointBias;const scratchTexelStepSize = new Cesium.Cartesian2();const texelStepSize = scratchTexelStepSize;texelStepSize.x = 1.0 / this.shadowMap._textureSize.x;texelStepSize.y = 1.0 / this.shadowMap._textureSize.y;return Cesium.Cartesian4.fromElements(texelStepSize.x,texelStepSize.y,bias.depthBias,bias.normalShadingSmooth,new Cesium.Cartesian4());}，camera_projection_matrix: this.lightCamera.frustum.projectionMatrix,camera_view_matrix: this.lightCamera.viewMatrix,helsing_viewDistance: () => {return this.viewDistance;},helsing_visibleAreaColor: this.visibleAreaColor,helsing_invisibleAreaColor: this.invisibleAreaColor,}});this.postStage = this.viewer.scene.postProcessStages.add(postStage);
}
创建视锥线：
drawFrustumOutline() {const scratchRight = new Cesium.Cartesian3();const scratchRotation = new Cesium.Matrix3();const scratchOrientation = new Cesium.Quaternion();const position = this.lightCamera.positionWC;const direction = this.lightCamera.directionWC;const up = this.lightCamera.upWC;let right = this.lightCamera.rightWC;right = Cesium.Cartesian3.negate(right, scratchRight);let rotation = scratchRotation;Cesium.Matrix3.setColumn(rotation, 0, right, rotation);Cesium.Matrix3.setColumn(rotation, 1, up, rotation);Cesium.Matrix3.setColumn(rotation, 2, direction, rotation);let orientation = Cesium.Quaternion.fromRotationMatrix(rotation, scratchOrientation);let instance = new Cesium.GeometryInstance({geometry: new Cesium.FrustumOutlineGeometry({frustum: this.lightCamera.frustum,origin: this.viewPosition,orientation: orientation}),id: Math.random().toString(36).substr(2),attributes: {color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.YELLOWGREEN//new Cesium.Color(0.0, 1.0, 0.0, 1.0)),show: new Cesium.ShowGeometryInstanceAttribute(true)}});this.frustumOutline = this.viewer.scene.primitives.add(new Cesium.Primitive({geometryInstances: [instance],appearance: new Cesium.PerInstanceColorAppearance({flat: true,translucent: false})}));
}
创建视网：
drawSketch() {this.sketch = this.viewer.entities.add({name: 'sketch',position: this.viewPosition,orientation: Cesium.Transforms.headingPitchRollQuaternion(this.viewPosition,Cesium.HeadingPitchRoll.fromDegrees(this.viewHeading - this.horizontalViewAngle, this.viewPitch, 0.0)),ellipsoid: {radii: new Cesium.Cartesian3(this.viewDistance,this.viewDistance,this.viewDistance),// innerRadii: new Cesium.Cartesian3(2.0, 2.0, 2.0),minimumClock: Cesium.Math.toRadians(-this.horizontalViewAngle / 2),maximumClock: Cesium.Math.toRadians(this.horizontalViewAngle / 2),minimumCone: Cesium.Math.toRadians(this.verticalViewAngle + 7.75),maximumCone: Cesium.Math.toRadians(180 - this.verticalViewAngle - 7.75),fill: false,outline: true,subdivisions: 256,stackPartitions: 64,slicePartitions: 64,outlineColor: Cesium.Color.YELLOWGREEN}});
}
获取偏航角和俯仰角：
function getHeading(fromPosition, toPosition) {let finalPosition = new Cesium.Cartesian3();let matrix4 = Cesium.Transforms.eastNorthUpToFixedFrame(fromPosition);Cesium.Matrix4.inverse(matrix4, matrix4);Cesium.Matrix4.multiplyByPoint(matrix4, toPosition, finalPosition);Cesium.Cartesian3.normalize(finalPosition, finalPosition);return Cesium.Math.toDegrees(Math.atan2(finalPosition.x, finalPosition.y));
}function getPitch(fromPosition, toPosition) {let finalPosition = new Cesium.Cartesian3();let matrix4 = Cesium.Transforms.eastNorthUpToFixedFrame(fromPosition);Cesium.Matrix4.inverse(matrix4, matrix4);Cesium.Matrix4.multiplyByPoint(matrix4, toPosition, finalPosition);Cesium.Cartesian3.normalize(finalPosition, finalPosition);return Cesium.Math.toDegrees(Math.asin(finalPosition.z));
}
自定义材质：
export default `#define USE_CUBE_MAP_SHADOW trueuniform sampler2D colorTexture;uniform sampler2D depthTexture;varying vec2 v_textureCoordinates;uniform mat4 camera_projection_matrix;uniform mat4 camera_view_matrix;uniform samplerCube shadowMap_textureCube;uniform mat4 shadowMap_matrix;uniform vec4 shadowMap_lightPositionEC;uniform vec4 shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness;uniform vec4 shadowMap_texelSizeDepthBiasAndNormalShadingSmooth;uniform float helsing_viewDistance;uniform vec4 helsing_visibleAreaColor;uniform vec4 helsing_invisibleAreaColor;struct zx_shadowParameters{vec3 texCoords;float depthBias;float depth;float nDotL;vec2 texelStepSize;float normalShadingSmooth;float darkness;};float czm_shadowVisibility(samplerCube shadowMap, zx_shadowParameters shadowParameters){float depthBias = shadowParameters.depthBias;float depth = shadowParameters.depth;float nDotL = shadowParameters.nDotL;float normalShadingSmooth = shadowParameters.normalShadingSmooth;float darkness = shadowParameters.darkness;vec3 uvw = shadowParameters.texCoords;depth -= depthBias;float visibility = czm_shadowDepthCompare(shadowMap, uvw, depth);return czm_private_shadowVisibility(visibility, nDotL, normalShadingSmooth, darkness);}vec4 getPositionEC(){return czm_windowToEyeCoordinates(gl_FragCoord);}vec3 getNormalEC(){return vec3(1.);}vec4 toEye(in vec2 uv,in float depth){vec2 xy=vec2((uv.x*2.-1.),(uv.y*2.-1.));vec4 posInCamera=czm_inverseProjection*vec4(xy,depth,1.);posInCamera=posInCamera/posInCamera.w;return posInCamera;}vec3 pointProjectOnPlane(in vec3 planeNormal,in vec3 planeOrigin,in vec3 point){vec3 v01=point-planeOrigin;float d=dot(planeNormal,v01);return(point-planeNormal*d);}float getDepth(in vec4 depth){float z_window=czm_unpackDepth(depth);z_window=czm_reverseLogDepth(z_window);float n_range=czm_depthRange.near;float f_range=czm_depthRange.far;return(2.*z_window-n_range-f_range)/(f_range-n_range);}float shadow(in vec4 positionEC){vec3 normalEC=getNormalEC();zx_shadowParameters shadowParameters;shadowParameters.texelStepSize=shadowMap_texelSizeDepthBiasAndNormalShadingSmooth.xy;shadowParameters.depthBias=shadowMap_texelSizeDepthBiasAndNormalShadingSmooth.z;shadowParameters.normalShadingSmooth=shadowMap_texelSizeDepthBiasAndNormalShadingSmooth.w;shadowParameters.darkness=shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness.w;vec3 directionEC=positionEC.xyz-shadowMap_lightPositionEC.xyz;float distance=length(directionEC);directionEC=normalize(directionEC);float radius=shadowMap_lightPositionEC.w;if(distance>radius){return 2.0;}vec3 directionWC=czm_inverseViewRotation*directionEC;shadowParameters.depth=distance/radius-0.0003;shadowParameters.nDotL=clamp(dot(normalEC,-directionEC),0.,1.);shadowParameters.texCoords=directionWC;float visibility=czm_shadowVisibility(shadowMap_textureCube,shadowParameters);return visibility;}bool visible(in vec4 result){result.x/=result.w;result.y/=result.w;result.z/=result.w;return result.x>=-1.&&result.x<=1.&&result.y>=-1.&&result.y<=1.&&result.z>=-1.&&result.z<=1.;}void main(){// 釉色 = 结构二维(颜色纹理, 纹理坐标)gl_FragColor = texture2D(colorTexture, v_textureCoordinates);// 深度 = 获取深度(结构二维(深度纹理, 纹理坐标))float depth = getDepth(texture2D(depthTexture, v_textureCoordinates));// 视角 = (纹理坐标, 深度)vec4 viewPos = toEye(v_textureCoordinates, depth);// 世界坐标vec4 wordPos = czm_inverseView * viewPos;// 虚拟相机中坐标vec4 vcPos = camera_view_matrix * wordPos;float near = .001 * helsing_viewDistance;float dis = length(vcPos.xyz);if(dis > near && dis < helsing_viewDistance){// 透视投影vec4 posInEye = camera_projection_matrix * vcPos;// 可视区颜色// vec4 helsing_visibleAreaColor=vec4(0.,1.,0.,.5);// vec4 helsing_invisibleAreaColor=vec4(1.,0.,0.,.5);if(visible(posInEye)){float vis = shadow(viewPos);if(vis > 0.3){gl_FragColor = mix(gl_FragColor,helsing_visibleAreaColor,.5);} else{gl_FragColor = mix(gl_FragColor,helsing_invisibleAreaColor,.5);}}}}`;
在使用的时候需开启深度检测
八、自定义弹窗
（一）思路
添加一个鼠标左键点击事件，当鼠标点击时，利用Vue.extend（）动态添加一个dom元素，将DOM元素渲染到cesium容器中，并利用cesium中提供的 viewer.scene.postRender 实时更新坐标位置。
（二）实现方法
1、创建地图容器
viewer = new Cesium.Viewer('cesiumContainer',{// terrainProvider: Cesium.createWorldTerrain(),// animation: false, // 控制场景动画的播放速度控件// baseLayerPicker: true, // 底图切换控件// baselLayerPicker:false,// 将图层选择的控件关掉，才能添加其他影像数据// // fullscreenButton: false, // 全屏控件// geocoder: false, // 地理位置查询定位控件// homeButton: true, // 默认相机位置控件// timeline: false, // 时间滚动条控件// infoBox: false, //是否显示信息框// sceneModePicker: false, //是否显示3D/2D选择器// selectionIndicator: false, // 点击点绿色弹出 是否显示选取指示器组件// sceneMode: Cesium.SceneMode.SCENE3D, //设定3维地图的默认场景模式:Cesium.SceneMode.SCENE2D、Cesium.SceneMode.SCENE3D、Cesium.SceneMode.MORPHING// navigationHelpButton: false, // 默认的相机控制提示控件// scene3DOnly: true, // 每个几何实例仅以3D渲染以节省GPU内存// navigationInstructionsInitiallyVisible: false,// showRenderLoopErrors: false, //是否显示渲染错误// orderIndependentTranslucency:false,//设置背景透明
});
2、billboard 添加目标点位
点位的数据格式：
poin : [{id:'12321321' ,name: "北京西路测试点",type: "固定枪机",state: "在线",position: { x: 116.4568,y: 39.8926} ,text:'X'
}],
将添加点的方法封装到类中：
/*** @param {Viewer} viewer*
*/
export default class DragEntity{constructor(val){this.viewer = val.viewer,}addEntity(value){//数据格式{id:543595234324_432423,position:[122.8,39.9],text:"L"}let pinBuilder = new Cesium.PinBuilder();let poin = this.viewer.entities.add({id:value.id,name: value.name,position: Cesium.Cartesian3.fromDegrees(value.position.x, value.position.y),billboard: {image: pinBuilder.fromText(value.text,Cesium.Color.ROYALBLUE, 48).toDataURL(),verticalOrigin: Cesium.VerticalOrigin.BOTTOM,},monitoItems:{data:value},});return poin}}
3、添加左键点击事件
leftDownAction(){let viewer = this.$store.state.viewerthis.handler = new Cesium.ScreenSpaceEventHandler(viewer.scene.canvas);let _this = thislet id_this.handler.setInputAction(function (movement) {let pick = viewer.scene.pick(movement.position); if (Cesium.defined(pick) && (pick.id.id) ) {// _this.leftDownFlag = true;id= pick.id.id;console.log(id)}}, Cesium.ScreenSpaceEventType.LEFT_CLICK);},
4、弹窗
export default class Bubble {constructor(val){this.viewer = val.viewerthis.div=document.createElement("div");// this.addDynamicLabel({id:1,position:val.position,title:"cl弹窗"});}addDynamicLabel(data){let div = this.divdiv.id = data.id;// div.style.display="inline"div.style.position = "absolute";div.style.width = "300px";div.style.height = "30px";let HTMLTable = `<div style="background:#00ffef66;height:200px;border:"1px soild #08f8a7">${data.text}<div style=""></div>`;div.innerHTML = HTMLTable;this.viewer.cesiumWidget.container.appendChild(div);let gisPosition = data.position._valuethis.viewer.scene.postRender.addEventListener(() => {const canvasHeight = this.viewer.scene.canvas.height;const windowPosition = new Cesium.Cartesian2();Cesium.SceneTransforms.wgs84ToWindowCoordinates(this.viewer.scene,gisPosition,windowPosition);div.style.bottom = canvasHeight - windowPosition.y +220 + "px";const elWidth = div.offsetWidth;div.style.left = windowPosition.x - elWidth / 2 + "px";}, this);}clearDiv(id){if(this.div){var parent = this.div.parentElement;parent.removeChild(this.div);// this.div.removeNode(true);this.viewer.scene.postRender.removeEventListener(this.addDynamicLabel,this)}}
}
修改点击事件：
import Bubble from './bubble/index.js'
leftDownAction(){let viewer = this.$store.state.viewerlet bubble = new Bubble({viewer:viewer })this.handler = new Cesium.ScreenSpaceEventHandler(viewer.scene.canvas);let _this = thislet id_this.handler.setInputAction(function (movement) {let pick = viewer.scene.pick(movement.position); if (Cesium.defined(pick) && (pick.id.id) ) {// _this.leftDownFlag = true;id= pick.id.id;let entiy = this.poinEntity[id];bubble.addDynamicLabel(entiy);}else{bubble.clearDiv();}}, Cesium.ScreenSpaceEventType.LEFT_CLICK);
},
九、cesium 广告牌优化
entityCollection 集合加上集群聚合功能，数据量临界点在 3w~4w 左右，就会出现界面卡顿。fps 低于 20 并且波动很大，延迟保持在 100ms 左右。
当数据量大于 10w+时，基本上 fps 处于 0-5，延迟大于 200ms，加载数据时延迟直接飙升几千都可能出现，同时（entityCollection 的）数据量过大直接导致浏览器崩溃无法加载。
抛开后台接口数据传递处理的优化，只针对前端 cesium 界面的所有优化方法中，billboardCollection 广告牌集合，也适合界面显示大量的 pointPrimitiveCollection（点集合）、labelCollection（label 集合）造成的界面卡顿。
优化方法：primitiveCollection与 primitiveCluster 结合使用
在不需要聚合集群的情况下，只使用 primitiveCollection就能够完美的解决广告牌 10w+造成的界面卡顿崩溃等问题。不需要聚合功能时，就不添加 primitiveCluster 来处理优化。因为聚合会监听摄像机的改变事件时刻改变聚合数量状态，反而会出现卡顿情况。
（一）primitiveCollection
广告牌集合添加代码（如下），其他的集合如 point、label，大同小异：
const billboardCollection = viewer.scene.primitives.add(new Cesium.BillboardCollection()
);
billboardCollection.add({position: Cesium.Cartesian3.fromDegrees(114.49, 41.23, 0),width: 38,height: 38,image: "xxxxx"
});
此时往 billboardCollection 中添加的 billboard 就会直接呈现在界面上，能够轻松应对 10w+的数据量。对比EntityCollection的添加方式效果很明显：
// 之前的添加方式
const entityCollection = new Cesium.EntityCollection();const billboard = new Cesium.BillboardGraphics({width: 38,height: 38,image: "xxxxx"
});
const entity = new Cesium.Entity({position: Cesium.Cartesian3.fromDegrees(114.49, 41.23, 0),billboard: billboard,s1: "xxx",s2: "xxx",s3: "xxx",s4: "xxx",s5: "xxx"
});
entityCollection.add(entity);
（二）PrimitiveCluster
primitiveCollection 的聚合功能官方并没有提供，在官方文档中只提供了 EntityCluster 方法，对 entityCollection 集合进行聚合操作。通过 EntityCluster 方法聚合时需要配合 datasource 对象使用，因为在原生的 datasource 对象自身有 clustering 属性。
由于我们直接使用的 Primitive 方式将 billboard 添加到地图中，就跳过了 datasource 的步骤。因此我们需要自己来定义一个 PrimitiveCluster 方法来创建一个 cluster 对象，针对原语集合进行聚合，结合其他博主文档提供的方法，PrimitiveCluster.js 具体实现方法总结如下：
一）往 cesium 的包文件或者依赖文件中添加 PrimitiveCluster 方法
1.添加的路径:
（1）npm 包中----- node_modules\cesium\Source\DataSources\PrimitiveCluster.js
（2）引入外部文件方式 ---- Source\DataSources\PrimitiveCluster.js
2.复制同目录下 EntityCluster.js 内容到 PrimitiveCluster.js 中
3.文件内全局修改名称，EntityCluster -> PrimitiveCluster、 entityCluster -> primitiveCluster
4.屏蔽 getScreenSpacePositions 方法中的代码块
（EntityCluster 中 item.id 指向的就是 entity 实体对象，在 primitiveCollection 中 item.id 为 undefined 会包错）
/* var canClusterLabels =primitiveCluster._clusterLabels && defined(item._labelCollection);
var canClusterBillboards =primitiveCluster._clusterBillboards && defined(item.id._billboard);
var canClusterPoints =primitiveCluster._clusterPoints && defined(item.id._point);
if (canClusterLabels && (canClusterPoints || canClusterBillboards)) {continue;
} */
第 4 步时 如果在添加广告牌时需要为广告牌添加唯一的标识 id（如下添加方式），则可以不用屏蔽源代码，添加的 id 能够规避此处报错
billboardCollection.add({id: "xxx",position: Cesium.Cartesian3.fromDegrees(114.49, 41.23, 0),width: 38,height: 38,image: "xxxxx"
});
5.在 PrimitiveCluster.js 的上级目录（node_modules\cesium\Source\Cesium.js）中找到入口文件 cesium.js，导入 PrimitiveCluster 方法
export { default as PrimitiveCluster } from "./DataSources/PrimitiveCluster.js";
可以直接通过 new Cesium.PrimitiveCluster()的方式来调用
二）PrimitiveCluster 方法来实现聚合
1.往 scene.primitives 中添加原语集合 primitives
2.创建一个空 billboardCollection 广告牌集合
3.通过 PrimitiveCluster 方法创建一个 cluster 实例对象 primitiveCluster
4.将 primitiveCluster 添加到集合 primitives 中
5.配置 primitiveCluster 对象的基本参数（不配置有默认参数）
6.将空 billboardCollection 广告牌集合赋予primitiveCluster._billboardCollection，手动添加聚合内容
primitiveCluster._labelCollection;
primitiveCluster._pointCollection;
7.调用_initialize 方法初始化 cluster 实例的事件监听
8.之后与 datasource 聚合方式的.then 方法一致，将 dataSource.clustering.clusterEvent.addEventListener 换成 primitiveCluster.clusterEvent.addEventListener
const primitives = viewer.scene.primitives.add(new Cesium.PrimitiveCollection()
);
const billboardCollection = new Cesium.BillboardCollection();const primitiveCluster = new Cesium.PrimitiveCluster();
primitives.add(primitiveCluster);
primitiveCluster.enabled = true; //开启聚合功能
primitiveCluster.pixelRange = 15; //范围
primitiveCluster.minimumClusterSize = 2; //最小聚合数量
primitiveCluster._billboardCollection = billboardCollection;
primitiveCluster._initialize(viewer.scene);primitiveCluster.clusterEvent.addEventListener(function(clusteredEntities,cluster
) {// ... 处理聚合显示广告牌代码块与dataSource处理方式一致
});
按照上面的方式完成聚合后，往 billboardCollection 集合中添加 billboard 广告牌就会在页面呈现出来并且聚合显示。但是数据量 10w+的情况下，在处理摄像机视角改变的监听事件时会出现卡顿问题。
（三）优化 PrimitiveCluster 卡顿问题
在 PrimitiveCluster.js 的_initialize 方法中，可以看到原方法使用 createDeclutterCallback 方法创建了一个回调方法，并将这个回调方法添加到了 scene.camera.changed 监听中。因此只要 scene.camera 视角改变，就会执行聚合的处理逻辑方法返回两个参数 clusteredEntities 与 cluster。
primitiveCluster.clusterEvent.addEventListener(function(clusteredEntities,cluster
) {// ... 处理聚合显示广告牌代码块与dataSource处理方式一致
});
只需要在_initialize 方法加一个防抖的定时器，让它事件处理频率降低就能达到优化的效果。同时暴露 delay 时间参数可以在实例化后进行配置改变
//1.PrimitiveCluster构造函数中添加_delay参数
this._delay = defaultValue(options.delay, 800)//2.在PrimitiveCluster.prototype拦截器Object.defineProperties方法中添加_delay的访问以及设置方法
delay: {get: function () {return this._delay;},set: function (value) {this._delay = value;},
},// 3._initialize方法改造
PrimitiveCluster.prototype._initialize = function(scene) {this._scene = scene;var cluster = createDeclutterCallback(this);this._cluster = cluster;var _t = null;const _self = this;this._removeEventListener = scene.camera.changed.addEventListener(function(amount) {if (_t) {clearTimeout(_t);_t = null;}_t = setTimeout(() => {cluster(amount);}, _self._delay);});
};
（四）功能代码记录
import * as Cesium from "cesium/Cesium";
import defaultValue from "./core/defaultValue";/*** @_v 引入外部创建的Viewer实例(new Cesium.Viewer(...))* @myPrimitives 原语集合，可以包含页面显示的pointPrimitiveCollection、billboardCollection、labelCollection、primitiveCollection、primitiveCluster* @myPrimitiveCluster 自定义原语集群* @myBillboardCollection 广告牌集合(站点显示的内容数据)** @desc 使用primitiveCollection原语集合与primitiveCluster原语集群，处理地图界面显示广告牌billboard数量 > 10w 级时，界面卡顿，浏览器崩溃等问题*/
class CommomSiteTookit {static _v = null;myPrimitives = null;myPrimitiveCluster = null;myBillboardCollection = null;constructor() {}/*** @desc 使用commomSiteTookit实例前，必须先初始化该实例的_v对象*/init(viewer) {this._v = viewer;}/*** @param [options] 具有以下属性的对象* @param [options.delay=800] 防抖处理定时器的time* @param [options.enabled=true] 是否启用集群* @param [options.pixelRange=15] 用于扩展屏幕空间包围框的像素范围* @param [options.minimumClusterSize=2] 可集群的屏幕空间对象的最小数量** @desc 处理原语集合，并实现聚合集群功能方法* @return billboardCollection集合，可直接往集合里添加广告牌billboard，呈现在页面上*/load(options = {}) {let billboardCollection = new Cesium.BillboardCollection();if (Cesium.defined(this.myPrimitives)) {this._v.scene.primitives.remove(this.myPrimitives);}this.myPrimitives = this._v.scene.primitives.add(new Cesium.PrimitiveCollection());const primitiveCluster = new Cesium.PrimitiveCluster();this.myPrimitives.add(primitiveCluster);primitiveCluster.delay = defaultValue(options.delay, 800);primitiveCluster.enabled = defaultValue(options.enabled, true);primitiveCluster.pixelRange = defaultValue(options.pixelRange, 15);primitiveCluster.minimumClusterSize = defaultValue(options.minimumClusterSize,2);primitiveCluster._billboardCollection = billboardCollection;primitiveCluster._initialize(this._v.scene);let removeListener;let pinBuilder = new Cesium.PinBuilder();/* 定义广告牌 fromText（显示文字，颜色，大小） */let pin50 = pinBuilder.fromText("50+", Cesium.Color.RED, 40).toDataURL();let pin40 = pinBuilder.fromText("40+", Cesium.Color.ORANGE, 40).toDataURL();let pin30 = pinBuilder.fromText("30+", Cesium.Color.YELLOW, 40).toDataURL();let pin20 = pinBuilder.fromText("20+", Cesium.Color.GREEN, 40).toDataURL();let pin10 = pinBuilder.fromText("10+", Cesium.Color.BLUE, 40).toDataURL();/* 数量小于十个的聚合广告牌 */let singleDigitPins = new Array(8);for (let i = 0; i < singleDigitPins.length; ++i) {singleDigitPins[i] = pinBuilder.fromText("" + (i + 2), Cesium.Color.VIOLET, 40).toDataURL();}const _ = this;function customStyle() {if (Cesium.defined(removeListener)) {removeListener();removeListener = undefined;} else {removeListener = primitiveCluster.clusterEvent.addEventListener(function(clusteredEntities, cluster) {cluster.label.show = false;cluster.billboard.show = true;cluster.billboard.id = cluster.label.id;cluster.billboard.verticalOrigin = Cesium.VerticalOrigin.BOTTOM;/* 根据站点(参数)的数量给予对应的广告牌 */if (clusteredEntities.length >= 50) {cluster.billboard.image = pin50;} else if (clusteredEntities.length >= 40) {cluster.billboard.image = pin40;} else if (clusteredEntities.length >= 30) {cluster.billboard.image = pin30;} else if (clusteredEntities.length >= 20) {cluster.billboard.image = pin20;} else if (clusteredEntities.length >= 10) {cluster.billboard.image = pin10;} else {cluster.billboard.image =singleDigitPins[clusteredEntities.length - 2];}});}// force a re-cluster with the new stylinglet pixelRange = primitiveCluster.pixelRange;primitiveCluster.pixelRange = 0;primitiveCluster.pixelRange = pixelRange;_.myPrimitiveCluster = primitiveCluster;}this.myBillboardCollection = billboardCollection;// start with custom stylecustomStyle();return billboardCollection;}/*** @params enable bool值控制开启或关闭集群* @desc 控制集群生效与否*/enableCluster(enable) {if (Cesium.defined(this.myPrimitiveCluster)) {this.myPrimitiveCluster.enabled = enable;}}/*** @params id 站点ID* @return 返回可操作的广告牌[siteBillboard.image = 'xxxx']* @desc 根据id在集合中获取指定站点广告牌*/getSiteBillboardById(id) {if (!Cesium.defined(this.myBillboardCollection)) return undefined;const _b = this.myBillboardCollection;const l = _b.length;let siteBillboard = undefined;for (let i = 0; i < l; i++) {if (id == _b.get(i).id) {siteBillboard = _b.get(i);break;}}return siteBillboard;}/*** @desc 删除所有站点广告牌*/removeAll() {if (Cesium.defined(this.myPrimitives)) {this._v.scene.primitives.remove(this.myPrimitives);}}/*** @params show bool值 控制显示或隐藏* @desc 隐藏或显示所有站点广告牌*/showStatus(show = true) {this.myPrimitives.show = show;}/*** @desc 根据id删除指定站点广告牌*/remove(id) {const billboard = this.getSiteBillboardById(id);billboard && this.myBillboardCollection.remove(billboard);}/*** @desc 销毁(目前退出页面时直接viewer销毁)*/destroy() {this.myPrimitives = null;this.myPrimitiveCluster = null;this.myBillboardCollection = null;// this._v.scene.primitives.destroy()}
}export default new CommomSiteTookit();
在执行commomSiteTookit.init(viewer)后，加载数据主要的操作在 load 方法中，load 返回的 billboardCollection，可以动态的添加 billboard 数据，直接呈现在界面，代码如下：
const list = ['10w+数据']
const l = list.length
const data = commomSiteTookit.load({enabled: true,delay: 1200,pixelRange: 20
});
for (let i = 0; i < l; i++) {data.add({image: `xxxx`,scaleByDistance: new Cesium.NearFarScalar(1.5e2, 1, 1.5e7, 0.2),width: 38, // default: undefinedheight: 38, // default: undefinedposition: Cesium.Cartesian3.fromDegrees(list[i].longitude,list[i].latitude,0),id: list[i].id + ""});
}
十、可视域分析
①利用高程判别：视角初始位置和视域目标点之间组成的一条直线，我们暂且称之为当前视角下的“视域线”，对该直线进行空间插值，获得直线上一系列的空间插值点。对于获取到的每个插值点P（x,y,z）通过getHeight()方法来获取当前场景下（x,y）点的地表高程h，对比z与h的高程关系。若z<h，则证明，该插值点位于地表下，可以归属于不可视域点；反之，若z>h，则归属于可视域点。这样就可以获取到视域线在当前插值精度下的可视域情况。
②pick取交：视角初始位置和视域目标点之间组成的一条射线（方向：视角位置→目标点），我们也称之为“视域线”，通过pickFromRay()方法，可以返回当前视域线与场景（地形或模型等）相交情况result。若result存在，则视角初始位置与result.position之间的区域归属于可视域范围，result.position与目标点之间的区域归属于不可视域范围；若result不存在，即无交点出现，全区域归属于可视域范围。
var createViewershed = function () {// 开启地形深度监测viewer.scene.globe.depthTestAgainstTerrain = true;// 设定初始视角位置点var viewPoint = Cesium.Cartesian3.fromDegrees(115.77774943, 40.51669238, 1000);var viewPointEntity = viewer.entities.add({position: viewPoint,ellipsoid: {radii: new Cesium.Cartesian3(5, 5, 5),material: Cesium.Color.YELLOW},});// 视角位置创建坐标轴var transform = Cesium.Transforms.eastNorthUpToFixedFrame(viewPoint);var modelMatrixPrimitive = viewer.scene.primitives.add(new Cesium.DebugModelMatrixPrimitive({modelMatrix: transform,length: 10.0}));// 世界坐标转换为投影坐标var webMercatorProjection = new Cesium.WebMercatorProjection(viewer.scene.globe.ellipsoid);var viewPointWebMercator = webMercatorProjection.project(Cesium.Cartographic.fromCartesian(viewPoint));// 排除碰撞监测的对象var objectsToExclude = [viewPointEntity, modelMatrixPrimitive];// 目标点集合var TargetPoints = [];// 视域点和目标点的距离var radius = 0;// 计算45°和135°之间的目标点for (var i = 45; i <= 135; i++) {var linePoints = [];//记录一条线上的所有目标点var pointsNum = 15;//该方向插值点数var lineDis = 200;//每两个插值点之间的距离m1for (let index = 0; index < pointsNum; index++) {radius = index * lineDis;// 度数转弧度var radians = Cesium.Math.toRadians(i);// 计算目标点var toPoint = new Cesium.Cartesian3(viewPointWebMercator.x + radius * Math.cos(radians), viewPointWebMercator.y + radius * Math.sin(radians), 0);// 投影坐标转世界坐标toPoint = webMercatorProjection.unproject(toPoint);// TargetPoints.push(Cesium.Cartographic.toCartesian(toPoint.clone()));var m_cartesian3 = Cesium.Cartographic.toCartesian(toPoint.clone());var m_ellipsoid = viewer.scene.globe.ellipsoid;var m_cartographic = m_ellipsoid.cartesianToCartographic(m_cartesian3);var m_height = viewer.scene.globe.getHeight(m_cartographic);var m_point = Cesium.Cartesian3.fromDegrees(m_cartographic.longitude / Math.PI * 180, m_cartographic.latitude / Math.PI * 180, m_height);linePoints.push({data: m_point,show: true});}TargetPoints.push({id: i,points: linePoints});}pickFromRay();function pickFromRay() {for (var i = 0; i < TargetPoints.length; i++) {var cur_LinePoints = TargetPoints[i].points;cur_LinePoints.forEach(element => {// 计算射线的方向，目标点left 视域点rightvar direction = Cesium.Cartesian3.normalize(Cesium.Cartesian3.subtract(element.data, viewPoint, new Cesium.Cartesian3()), new Cesium.Cartesian3());// 建立射线var ray = new Cesium.Ray(viewPoint, direction);// var results = viewer.scene.drillPickFromRay(ray, 10, objectsToExclude); // 计算所有的交互点，最大不超过10个var result = viewer.scene.pickFromRay(ray, objectsToExclude); // 计算交互点，返回第一个var buffer = ReturnDistance(element.data, result.position);// var M_color = Cesium.Color.GREEN;if (buffer > 10) {// M_color = Cesium.Color.RED;element.show = false;}//添加当前视域目标点可视化信息// viewer.entities.add({// name: "aaaa" + i,// position: element.data,// ellipsoid: {// radii: new Cesium.Cartesian3(30, 30, 30),// material: M_color// },// })});}drawViewshedLine(TargetPoints);}function drawViewshedLine(data) {for (let index = 0; index < data.length; index++) {const element = data[index].points;var startIndex = 0;for (let i = 0; i < element.length; i++) {var defaultColor = new Cesium.Color(0.1, 1, 0.1, 0.3);// console.log("第" + i + '个点的起点是：' + startIndex);const m_linestart = element[startIndex];var m_lineshow = m_linestart.show;const m_lineCurrent = element[i];const m_lineEnd = element[i + 1];if (m_lineEnd && m_lineCurrent.show != m_lineEnd.show) {if (!m_lineshow) {defaultColor = new Cesium.Color(1, 0.1, 0.1, 0.3);}viewer.entities.add({polyline: {positions: [m_linestart.data, m_lineEnd.data],width: 2,material: defaultColor,clampToGround: true}});startIndex = i + 1;}else if (!m_lineEnd) {if (!m_lineshow) {defaultColor = new Cesium.Color(1, 0.1, 0.1, 0.3);}viewer.entities.add({polyline: {positions: [m_linestart.data, m_lineCurrent.data],// arcType: Cesium.ArcType.NONE,width: 2,material: defaultColor,// depthFailMaterial: defaultColor,clampToGround: true}});}}}}//空间两点距离计算函数function ReturnDistance(pos0, pos1) {var distance = 0;var point1cartographic = Cesium.Cartographic.fromCartesian(pos0);var point2cartographic = Cesium.Cartographic.fromCartesian(pos1);/**根据经纬度计算出距离**/var geodesic = new Cesium.EllipsoidGeodesic();geodesic.setEndPoints(point1cartographic, point2cartographic);var s = geodesic.surfaceDistance;return s.toFixed(2);}// 处理交互点function showIntersection(result, destPoint, viewPoint) {// 如果是场景模型的交互点，排除交互点是地球表面if (Cesium.defined(result) && Cesium.defined(result.object)) {drawLine(result.position, viewPoint, Cesium.Color.GREEN); // 可视区域drawLine(result.position, destPoint, Cesium.Color.RED); // 不可视区域} else {drawLine(viewPoint, destPoint, Cesium.Color.GREEN);}}
}
