cesium的entity的操作

作者: 清远_03d9 | 来源:发表于2019-10-29 22:33 被阅读0次

entity操作https://www.jianshu.com/p/8ae3624347cb

1. entity的操作：添加、隐藏、修改、去除、居中显示

Var rainEntity=viewer.entities.add({
       id: "rain",
     name: 'RainStation',
     parent: rainLayer3D,                
     position: Cesium.Cartesian3.fromDegrees(lon, lat),
    billboard: {
        image: 'images/pointIcons/rain1.png',
        scale:0.7,
        verticalOrigin: Cesium.VerticalOrigin.BOTTOM
    },
    label: {
              text: rainfall,
              font: '12px SimHei ',
              Width: 3,
         style: Cesium.LabelStyle.FILL,
              fillColor: Cesium.Color.AQUA,
              horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
              verticalOrigin: Cesium.VerticalOrigin.TOP
    }
  });  //添加

viewer.entities.getById("rain").show = false;   //隐藏
viewer.entities.getById("rain").label.text= "drp";   //修改属性
viewer.entities.removeAll();  //移除所有
viewer.zoomTo(rainEntity);   //居中显示

2. 去掉entity的双击事件

问题所在：双击entity，会放大视图，entity居中显示，且鼠标左键失去移动功能，鼠标滚轮失去作用
解决问题：
viewer.screenSpaceEventHandler.setInputAction(function(){},Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK );
获取当前视角高度
var scene = viewer.scene;
var ellipsoid = scene.globe.ellipsoid;
var height=ellipsoid.cartesianToCartographic(viewer.camera.position).height;

禁用事件

//大批量操作时，临时禁用事件可以提高性能
viewer.entities.suspendEvents();
//执行各种Entity操作
viewer.entities.resumeEvents();

3. 创建一个entity

var viewer = new Cesium.Viewer('cesiumContainer');

var wyoming = viewer.entities.add({
  name : 'Wyoming',
  polygon : {
    hierarchy : Cesium.Cartesian3.fromDegreesArray([
                              -109.080842,45.002073,
                              -105.91517,45.002073,
                              -104.058488,44.996596,
                              -104.053011,43.002989,
                              -104.053011,41.003906,
                              -105.728954,40.998429,
                              -107.919731,41.003906,
                              -109.04798,40.998429,
                              -111.047063,40.998429,
                              -111.047063,42.000709,
                              -111.047063,44.476286,
                              -111.05254,45.002073]),
    height : 0,
    material : Cesium.Color.RED.withAlpha(0.5),
    outline : true,
    outlineColor : Cesium.Color.BLACK
  }
});

viewer.zoomTo(wyoming);

4.Entity支持的所有的面和体

(1)折线 entity.polyline

折线 entity.polyline
折线设置宽度

var entity = viewer.entities.add({
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArray([-77, 35,
                                                        -77.1, 35]),
    width : 5,
    material : Cesium.Color.RED
}});
viewer.zoomTo(viewer.entities);
var polyline = entity.polyline // For upcoming examples

折线可设置宽度
折线边线

polyline.material = new Cesium.PolylineOutlineMaterialProperty({
    color : Cesium.Color.ORANGE,
    outlineWidth : 3,
    outlineColor : Cesium.Color.BLACK
});

折线边线

折线辉光

polyline.material = new Cesium.PolylineGlowMaterialProperty({
    glowPower : 0.2,
    color : Cesium.Color.BLUE
});

var redLine = viewer.entities.add({
    name : '沿着地球表面的红线',
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArray(
            [-75, 35,
             -125, 35]),
        width : 5,
        material : Cesium.Color.RED
    }
});
 
var glowingLine = viewer.entities.add({
    name : '具有发光效果的线',
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArray(
            [-75, 37, -125, 37]
        ),
        width : 10,
        material : new Cesium.PolylineGlowMaterialProperty({
            glowPower : 0.2,
            color : Cesium.Color.BLUE
        })
    }
});
 
var orangeOutlined = viewer.entities.add({
    name : '具有一定高度的线',
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights(
            [-75, 39, 250000,-125, 39, 250000]
        ),
        width : 5,
        material : new Cesium.PolylineOutlineMaterialProperty({
            color : Cesium.Color.ORANGE,
            outlineWidth : 2,
            outlineColor : Cesium.Color.BLACK
        })
    }
});
 
var yellowLine = viewer.entities.add({
    name : '不贴着地表的线',
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights(
            [-75, 43, 500000,-125, 43, 500000]
        ),
        width : 3,
        followSurface : false,  //是否贴着地表
        material : Cesium.Color.PURPLE
    }
});

(2) 多边形 entity.polygon

多边形 entity.polygon

var redPolygon = viewer.entities.add({
    name : '贴着地表的多边形',
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArray([-115.0, 37.0,
                                                        -115.0, 32.0,
                                                        -107.0, 33.0,
                                                        -102.0, 31.0,
                                                        -102.0, 35.0]),
        material : Cesium.Color.RED
    }
});
 
var greenPolygon = viewer.entities.add({
    name : '绿色拉伸多边形',
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArray([-108.0, 42.0,
                                                        -100.0, 42.0,
                                                        -104.0, 40.0]),
        extrudedHeight: 500000.0,
        material : Cesium.Color.GREEN
    }
});
 
var orangePolygon = viewer.entities.add({
    name : '每个顶点具有不同拉伸高度的橘色多边形',
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArrayHeights(
            [-108.0, 25.0, 100000,
             -100.0, 25.0, 100000,
             -100.0, 30.0, 100000,
             -108.0, 30.0, 300000]),
        extrudedHeight: 0,
        perPositionHeight : true,
        material : Cesium.Color.ORANGE,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});
 
var bluePolygon = viewer.entities.add({
    name : '具有挖空效果的蓝色多边形',
    polygon : {
        hierarchy : {
            positions : Cesium.Cartesian3.fromDegreesArray(
                [-99.0, 30.0,
                 -85.0, 30.0,
                 -85.0, 40.0,
                 -99.0, 40.0]),
            holes : [{
                positions : Cesium.Cartesian3.fromDegreesArray([
                    -97.0, 31.0,
                    -97.0, 39.0,
                    -87.0, 39.0,
                    -87.0, 31.0
                ]),
                holes : [{
                    positions : Cesium.Cartesian3.fromDegreesArray([
                        -95.0, 33.0,
                        -89.0, 33.0,
                        -89.0, 37.0,
                        -95.0, 37.0
                    ]),
                    holes : [{
                        positions : Cesium.Cartesian3.fromDegreesArray([
                            -93.0, 34.0,
                            -91.0, 34.0,
                            -91.0, 36.0,
                            -93.0, 36.0
                        ])
                    }]
                }]
            }]
        },
        material : Cesium.Color.BLUE,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});

高度和垂直挤压设置

圆（circles）、椭圆（ellipses）、多边形（polygons）、矩形（rectangles）可以有一个高程属性或者垂直挤压变成体

wyoming.polygon.height = 200000;
wyoming.polygon.extrudedHeight = 250000;

11335939-43f79422edc13b7b.jpg

(3) 矩形 entity.rectangle

矩形 entity.rectangle

/红色矩形
var redRectangle = viewer.entities.add({
    name : 'Red translucent rectangle with outline',
    rectangle : {
        coordinates : Cesium.Rectangle.fromDegrees(-110.0, 20.0, -80.0, 25.0),
        material : Cesium.Color.RED.withAlpha(0.5),
        outline : true,
        outlineColor : Cesium.Color.RED
    }
});
//绿色旋转、拉伸的矩形
var greenRectangle = viewer.entities.add({
    name : 'Green translucent, rotated, and extruded rectangle',
    rectangle : {
        coordinates : Cesium.Rectangle.fromDegrees(-100.0, 30.0, -90.0, 40.0),
        material : Cesium.Color.GREEN.withAlpha(0.5),
        rotation : Cesium.Math.toRadians(45),
        extrudedHeight : 300000.0,
        height : 100000.0,
        outline : true,
        outlineColor : Cesium.Color.GREEN
    }
});

(4) 圆和椭圆entity.ellipse

圆和椭圆entity.ellipse

ar viewer = new Cesium.Viewer('cesiumContainer');
//浮空的绿色圆形
var greenCircle = viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(-111.0, 40.0, 150000.0),
    name : 'Green circle at height',
    ellipse : {
        semiMinorAxis : 300000.0,
        semiMajorAxis : 300000.0,
        height: 200000.0, //浮空
        material : Cesium.Color.GREEN
    }
});
//红色椭圆形，位于地表，带轮廓
var redEllipse = viewer.entities.add({
    //不带高度
    position: Cesium.Cartesian3.fromDegrees(-103.0, 40.0),
    name : 'Red ellipse on surface with outline',
    ellipse : {
        semiMinorAxis : 250000.0,
        semiMajorAxis : 400000.0,
        material : Cesium.Color.RED.withAlpha(0.5),
        outline : true,
        outlineColor : Cesium.Color.RED
    }
});
//蓝色椭圆柱，旋转了角度
var blueEllipse = viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(-95.0, 40.0, 100000.0),
    name : 'Blue translucent, rotated, and extruded ellipse',
    ellipse : {
        semiMinorAxis : 150000.0,
        semiMajorAxis : 300000.0,
        extrudedHeight : 200000.0,  //拉伸
        rotation : Cesium.Math.toRadians(45), //旋转
        material : Cesium.Color.BLUE.withAlpha(0.7),
        outline : true
    }
});
 
viewer.zoomTo(viewer.entities);

(5) Corridor entity.corridor

Corridor entity.corridor

ar redCorridor = viewer.entities.add({
    name : 'Red corridor on surface with rounded corners and outline',
    corridor : {
        positions : Cesium.Cartesian3.fromDegreesArray([
                                                        -100.0, 40.0,
                                                        -105.0, 40.0,
                                                        -105.0, 35.0
                                                    ]),
                                                    width : 200000.0,
        material : Cesium.Color.RED.withAlpha(0.5),
        outline : true,
        outlineColor : Cesium.Color.RED
    }
});
 
var greenCorridor = viewer.entities.add({
    name : 'Green corridor at height with mitered corners',
    corridor : {
        positions : Cesium.Cartesian3.fromDegreesArray(
        [    -90.0, 40.0,
             -95.0, 40.0,
             -95.0, 35.0
        ]),
        height: 100000.0,
        width : 200000.0,
        cornerType: Cesium.CornerType.MITERED,
        material : Cesium.Color.GREEN
    }
});
 
var blueCorridor = viewer.entities.add({
    name : 'Blue extruded corridor with beveled corners and outline',
    corridor : {
        positions : Cesium.Cartesian3.fromDegreesArray(
        [    80.0, 40.0,
             -85.0, 40.0,
             -85.0, 35.0
        ]),
        height : 200000.0,
        extrudedHeight : 100000.0,
        width : 200000.0,
        cornerType: Cesium.CornerType.BEVELED,
        material : Cesium.Color.BLUE.withAlpha(0.5),
        outline : true,
        outlineColor : Cesium.Color.BLUE
    }
});

(6) 六面体盒子entity.box

六面体盒子entity.box

var blueBox = viewer.entities.add({
    name : 'Blue box',
     //中心的位置
    position: Cesium.Cartesian3.fromDegrees(-114.0, 40.0, 300000.0),
    box : {
        //长宽高
        dimensions : new Cesium.Cartesian3(400000.0, 300000.0, 500000.0),
        material : Cesium.Color.BLUE
    }
});
 
var redBox = viewer.entities.add({
    name : 'Red box with black outline',
    position: Cesium.Cartesian3.fromDegrees(-107.0, 40.0, 300000.0),
    box : {
        dimensions : new Cesium.Cartesian3(400000.0, 300000.0, 500000.0),
        material : Cesium.Color.RED,
        outline : true, //显示轮廓
        outlineColor : Cesium.Color.BLACK
    }
});
 
var outlineOnly = viewer.entities.add({
    name : 'Yellow box outline',
    position: Cesium.Cartesian3.fromDegrees(-100.0, 40.0, 300000.0),
    box : {
        dimensions : new Cesium.Cartesian3(400000.0, 300000.0, 500000.0),
        fill : false,  //不显示填充
        outline : true,
        outlineColor : Cesium.Color.YELLOW
    }
});

(7) 圆柱和圆锥 entity.cylinder

圆柱和圆锥 entity.cylinder

var greenCylinder = viewer.entities.add({
    name : 'Green cylinder with black outline',
    position: Cesium.Cartesian3.fromDegrees(-100.0, 40.0, 200000.0),
    cylinder : { //圆柱
        length : 400000.0,
        topRadius : 200000.0,
        bottomRadius : 200000.0,
        material : Cesium.Color.GREEN,
        outline : true,
        outlineColor : Cesium.Color.DARK_GREEN
    }
});
 
var redCone = viewer.entities.add({
    name : 'Red cone',
    position: Cesium.Cartesian3.fromDegrees(-105.0, 40.0, 200000.0),
    cylinder : {//圆锥
        length : 400000.0,
        topRadius : 0.0,
        bottomRadius : 200000.0,
        material : Cesium.Color.RED
    }
});

(8) Polyline Volumes entity.polylineVolume

Polyline Volumes entity.polylineVolume

var viewer = new Cesium.Viewer('cesiumContainer');
 
function computeCircle(radius) {
    var positions = [];
    for (var i = 0; i < 360; i++) {
        var radians = Cesium.Math.toRadians(i);
        positions.push(new Cesium.Cartesian2(
            radius * Math.cos(radians), radius * Math.sin(radians)));
    }
    return positions;
}
 
function computeStar(arms, rOuter, rInner) {
    var angle = Math.PI / arms;
    var length = 2 * arms;
    var positions = new Array(length);
    for (var i = 0; i < length; i++) {
        var r = (i % 2) === 0 ? rOuter : rInner;
        positions[i] = new Cesium.Cartesian2(
            Math.cos(i * angle) * r, Math.sin(i * angle) * r);
    }
    return positions;
}
 
var redTube = viewer.entities.add({
    name : 'Red tube with rounded corners',
    polylineVolume : {
        positions : Cesium.Cartesian3.fromDegreesArray(
            [-85.0, 32.0,
             -85.0, 36.0,
             -89.0, 36.0]),
        shape : computeCircle(60000.0),
        material : Cesium.Color.RED
    }
});
 
var greenBox = viewer.entities.add({
    name : 'Green box with beveled corners and outline',
    polylineVolume : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights(
            [-90.0, 32.0, 0.0,
             -90.0, 36.0, 100000.0,
             -94.0, 36.0, 0.0]),
        shape :[new Cesium.Cartesian2(-50000, -50000),
                new Cesium.Cartesian2(50000, -50000),
                new Cesium.Cartesian2(50000, 50000),
                new Cesium.Cartesian2(-50000, 50000)],
        cornerType : Cesium.CornerType.BEVELED,
        material : Cesium.Color.GREEN,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});
 
var blueStar = viewer.entities.add({
    name : 'Blue star with mitered corners and outline',
    polylineVolume : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights(
            [-95.0, 32.0, 0.0,
             -95.0, 36.0, 100000.0,
             -99.0, 36.0, 200000.0]),
        shape : computeStar(7, 70000, 50000),
        cornerType : Cesium.CornerType.MITERED,
        material : Cesium.Color.BLUE,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});
 
viewer.zoomTo(viewer.entities);

(9) 球和椭球 entity.ellipsoid

球和椭球 entity.ellipsoid

var blueEllipsoid = viewer.entities.add({
    name : 'Blue ellipsoid',
    position: Cesium.Cartesian3.fromDegrees(-114.0, 40.0, 300000.0),
    ellipsoid : {
        //可以指定三个轴的半径
        radii : new Cesium.Cartesian3(200000.0, 200000.0, 300000.0),
        material : Cesium.Color.BLUE
    }
});
 
var redSphere = viewer.entities.add({
    name : 'Red sphere with black outline',
    position: Cesium.Cartesian3.fromDegrees(-107.0, 40.0, 300000.0),
    ellipsoid : {
        //正球体
        radii : new Cesium.Cartesian3(300000.0, 300000.0, 300000.0),
        material : Cesium.Color.RED,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});
 
var outlineOnly = viewer.entities.add({
    name : 'Yellow ellipsoid outline',
    position: Cesium.Cartesian3.fromDegrees(-100.0, 40.0, 300000.0),
    ellipsoid : {
        radii : new Cesium.Cartesian3(200000.0, 200000.0, 300000.0),
        fill : false,
        outline : true,
        outlineColor : Cesium.Color.YELLOW,
        slicePartitions : 24, //横向切割线
        stackPartitions : 36  //纵向切割线
    }
});

(10) 墙 entity.wall

墙 entity.wall

/东西方向的横墙
var redWall = viewer.entities.add({
    name : 'Red wall at height',
    wall : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights(
             [-115.0, 44.0, 200000.0,//坐标点
              -90.0, 44.0, 200000.0]
        ),
        minimumHeights : [100000.0, 100000.0], //按坐标点的最小高度数组
        material : Cesium.Color.RED
    }
});
//四边围墙
var greenWall = viewer.entities.add({
    name : 'Green wall from surface with outline',
    wall : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights(
            [-107.0, 43.0, 100000.0,
             -97.0, 43.0, 100000.0,
             -97.0, 40.0, 100000.0,
             -107.0, 40.0, 100000.0,
             -107.0, 43.0, 100000.0]),
        material : Cesium.Color.GREEN,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});
//曲折的墙
var blueWall = viewer.entities.add({
    name : 'Blue wall with sawtooth heights and outline',
    wall : {
        //坐标点，不指定高度
        positions : Cesium.Cartesian3.fromDegreesArray(
            [-115.0, 50.0,
             -112.5, 50.0,
             -110.0, 50.0,
             -107.5, 50.0,
             -105.0, 50.0,
             -102.5, 50.0,
             -100.0, 50.0,
             -97.5, 50.0,
             -95.0, 50.0,
             -92.5, 50.0,
             -90.0, 50.0]),
        maximumHeights : [ //上高
            100000, 200000, 100000, 200000, 100000, 200000, 
            100000, 200000, 100000, 200000, 100000],
        minimumHeights : [  //下高
            0, 100000,  0, 100000, 0, 100000, 0, 100000, 0,
            100000, 0],
        material : Cesium.Color.BLUE,
        outline : true,
        outlineColor : Cesium.Color.BLACK
    }
});

(11) 点（Points）,公告牌（ Billboards）, 标注（Labels）

var viewer = new Cesium.Viewer('cesiumContainer');

var citizensBankPark = viewer.entities.add({
    name : 'Citizens Bank Park',
    position : Cesium.Cartesian3.fromDegrees(-75.166493, 39.9060534),
    point : {
        pixelSize : 5,
        color : Cesium.Color.RED,
        outlineColor : Cesium.Color.WHITE,
        outlineWidth : 2
    },
    label : {
        text : 'Citizens Bank Park',
        font : '14pt monospace',
        style: Cesium.LabelStyle.FILL_AND_OUTLINE,
        outlineWidth : 2,
        verticalOrigin : Cesium.VerticalOrigin.BOTTOM,
        pixelOffset : new Cesium.Cartesian2(0, -9)
    }
});

viewer.zoomTo(viewer.entities);

点,公告牌, 标注

12. 三维模型

加载三维模型和前面其他的可视数据区别不大。只需要entity带position属性和一个指向glTF模型资源的uri路径。

var viewer = new Cesium.Viewer('cesiumContainer');
var entity = viewer.entities.add({
    position : Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706),
    model : {
        uri : '../../../../Apps/SampleData/models/GroundVehicle/GroundVehicle.glb'
    }
});
viewer.trackedEntity = entity;

三维模型

scale 属性，它将等比例缩放模型。
minimumPixelSize 属性，它保证距离模型很远的时候，模型不会小于设定的大小

默认，模型向右朝向东方。可以通过 Entity.orientation 的属性设定一个四元数Quaternion。这个比前面只用位置的示例更麻烦一些，让我们设定一下模型的 heading, pitch, roll

var viewer = new Cesium.Viewer('cesiumContainer');
var position = Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706);
var heading = Cesium.Math.toRadians(45.0);
var pitch = Cesium.Math.toRadians(15.0);
var roll = Cesium.Math.toRadians(0.0);
var orientation = Cesium.Transforms.headingPitchRollQuaternion(position, new Cesium.HeadingPitchRoll(heading, pitch, roll));

var entity = viewer.entities.add({
    position : position,
    orientation : orientation,
    model : {
        uri : '../../../../Apps/SampleData/models/GroundVehicle/GroundVehicle.glb'
    }
});
viewer.trackedEntity = entity;

5. 常用属性

fill：boolean类型，控制表面是否填充；
outline：属性控制是否有外边界；
material：当 fill=true，material属性决定了用什么材质填充表面；默认fill=true， outline=false；

6. material设置

var entity = viewer.entities.add({
  position: Cesium.Cartesian3.fromDegrees(-103.0, 40.0),
  ellipse : {
    semiMinorAxis : 250000.0,
    semiMajorAxis : 400000.0,
    material : Cesium.Color.BLUE.withAlpha(0.5)
  }
});
viewer.zoomTo(viewer.entities);
var ellipse = entity.ellipse;

material设置为蓝色的效果

图片材质

ellipse.material = '//cesiumjs.org/tutorials/images/cats.jpg';

material设置为图片的效果

当设置颜色或者url之后Cesium会自动创建 ColorMaterialProperty 或者ImageMaterialProperty对象。对于更复杂的材质, 需要手动创建 MaterialProperty对象。当前, Entity 面和体支持颜色(colors),纹理图片（ images）,棋盘（checkerboard）, 条纹（stripe）, 网格（grid）等材质.

网格材质

ellipse.material = new Cesium.CheckerboardMaterialProperty({
  evenColor : Cesium.Color.WHITE,
  oddColor : Cesium.Color.BLACK,
  repeat : new Cesium.Cartesian2(4, 4)
});

网络材质

条纹材质

ellipse.material = new Cesium.StripeMaterialProperty({
  evenColor : Cesium.Color.WHITE,
  oddColor : Cesium.Color.BLACK,
  repeat : 32
});

条纹材质

网格材质

ellipse.material = new Cesium.GridMaterialProperty({
  color : Cesium.Color.YELLOW,
  cellAlpha : 0.2,
  lineCount : new Cesium.Cartesian2(8, 8),
  lineThickness : new Cesium.Cartesian2(2.0, 2.0)
});

网格材质

7. outline设置

outlineWidth ：仅在非windows系统上有效，比如Android, iOS, Linux, 和OS X，Windows系统上边线宽度永远为1。主要是因为三大主流浏览器引擎在windows平台上实现webgl上的技术限制。
outlineColor：

ellipse.fill = false;
ellipse.outline = true;
ellipse.outlineColor = Cesium.Color.YELLOW;
ellipse.outlineWidth = 2.0;

outline

折线是个特例，折线宽度和折线的边线宽度，在所有系统都有效

var entity = viewer.entities.add({
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArray([-77, 35,
                                                        -77.1, 35]),
    width : 5,
    material : Cesium.Color.RED
}});
viewer.zoomTo(viewer.entities);
var polyline = entity.polyline // For upcoming examples

折线可设置宽度

8. 相关函数设置

1. 选中和描述

点击Entity将在它的位置会显示 SelectionIndicator 控件，entity设置了name属性，它显示在 InfoBox标题栏，也可以通过 Entity.description 设置一段HTML当作infobox的内容。把下面的代码追加到上面的示例里：

yoming.description = '\
<img\
  width="50%"\
  style="float:left; margin: 0 1em 1em 0;"\
  src="//cesiumjs.org/tutorials/Visualizing-Spatial-Data/images/Flag_of_Wyoming.svg"/>\
<p>\
  Wyoming is a state in the mountain region of the Western \
  United States.\
</p>\
<p>\
  Wyoming is the 10th most extensive, but the least populous \
  and the second least densely populated of the 50 United \
  States. The western two thirds of the state is covered mostly \
  with the mountain ranges and rangelands in the foothills of \
  the eastern Rocky Mountains, while the eastern third of the \
  state is high elevation prairie known as the High Plains. \
  Cheyenne is the capital and the most populous city in Wyoming, \
  with a population estimate of 62,448 in 2013.\
</p>\
<p>\
  Source: \
  <a style="color: WHITE"\
    target="_blank"\
    href="http://en.wikipedia.org/wiki/Wyoming">Wikpedia</a>\
</p>';

选中弹出描述

9. 获取Entity

1. 通过 getById来获取Entity对象

var entity = viewer.entities.getById('uniqueId');

2. 如果id不存在就新建，如果id存在就更新

var entity = viewer.entities.getOrCreateEntity('uniqueId');

10. 接收集合里entity被添加、删除甚至更新的通知

function onChanged(collection, added, removed, changed){
  var msg = 'Added ids';
  for(var i = 0; i < added.length; i++) {
    msg += '\n' + added[i].id;
  }
  console.log(msg);
}
viewer.entities.collectionChanged.addEventListener(onChanged);

11.拾取（也可参考网站cesium学习笔记）

拾取，也就是返回特定屏幕坐标（通常是鼠标位置）的对象

/**
 * 返回对应窗口位置最上面一个Entity 如果该位置没有对象那么返回undefined
 * @param {Cartesian2} windowPosition 窗口坐标
 * @returns {Entity} 返回值
 */
function pickEntity(viewer, windowPosition) {
  var picked = viewer.scene.pick(windowPosition);
  if (Cesium.defined(picked)) {
    var id = Cesium.defaultValue(picked.id, picked.primitive.id);
    if (id instanceof Cesium.Entity) {
      return id;
    }
  }
  return undefined;
};

/**
 *返回对应窗口位置所有Entity的列表 如果该位置没有对象那么返回undefined
 * 返回值按可视化顺序从前到后存储在数组里
 *
 * @param {Cartesian2} windowPosition 窗口位置
 * @returns {Entity[]}  
 */
function drillPickEntities(viewer, windowPosition) {
  var i;
  var entity;
  var picked;
  var pickedPrimitives = viewer.scene.drillPick(windowPosition);
  var length = pickedPrimitives.length;
  var result = [];
  var hash = {};

  for (i = 0; i < length; i++) {
    picked = pickedPrimitives[i];
    entity = Cesium.defaultValue(picked.id, picked.primitive.id);
    if (entity instanceof Cesium.Entity &&
        !Cesium.defined(hash[entity.id])) {
      result.push(entity);
      hash[entity.id] = true;
    }
  }
  return result;
};