cesium 自定义动态标记
# 效果
图中效果源代码在下面的封装栏中
效果展示：https://www.bilibili.com/video/BV1db4y167z7
# 基本思路
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。思路很简单，接下来我们进行实现。
# 实现方法
首先我们需要生成一个球体做我们标记的容器。
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
});
然后我们在vue methods中构建一个方法，设定我们想要配置的参数对象data
| data{ position:[106,125]，title:"标题"，id:"0" } | position：经纬度 title：文本标题， id：唯一标识 |
addDynamicLabel(data){
// 此处编写代码
}
**我们需要用js中 document.createElement 来动态添加一个div标记并设其样式内容，并利用cesium中 viewer.cesiumWidget.container.appendChild() 将动态添加的div添加到cesium容器中 **
addDynamicLabel(data){
let div = document.createElement("div");
div.id = data.id;
div.style.position = "absolute";
div.style.width = "100px";
div.style.height = "30px";
let HTMLTable = `
${data.title}
`;
div.innerHTML = HTMLTable;
viewer.cesiumWidget.container.appendChild(div);
}
虽然我们将div添加到了cesium容器中，但是并不能显示到我们想要的位置，具体原因是因为我们并未有给添加的标签设置top和left值，接下来我们需要根据传入的坐标转换成屏幕xy值，我们可以利用cesium中提供的 Cesium.SceneTransforms.wgs84ToWindowCoordinates() 方法进行转化
addDynamicLabel(data){
let div = document.createElement("div");
div.id = data.id;
div.style.position = "absolute";
div.style.width = "100px";
div.style.height = "30px";
let HTMLTable = `
${data.title}
`;
div.innerHTML = HTMLTable;
viewer.cesiumWidget.container.appendChild(div);
let gisPosition = Cesium.Cartesian3.fromDegrees(
data.position[0],
data.position[1],
0
);
const canvasHeight = viewer.scene.canvas.height;
const windowPosition = new Cesium.Cartesian2();
Cesium.SceneTransforms.wgs84ToWindowCoordinates(
viewer.scene,
gisPosition,
windowPosition
);
div.style.bottom = canvasHeight - windowPosition.y + "px";
const elWidth = div.offsetWidth;
div.style.left = windowPosition.x - elWidth / 2 + "px";
}
现在咱们自定义的标记已经显示到我们想要的位置了，但是我们还出现了一个问题我们在移动地球的时候，标签不会跟着动，总不能不能让用户操作呀，在那摆着当个花瓶看。那不可能，我们可以在看cesium给咱们提供的文档中有一个 viewer.scene.postRender 方法实时更新位置
addDynamicLabel(data){
let div = document.createElement("div");
div.id = data.id;
div.style.position = "absolute";
div.style.width = "100px";
div.style.height = "30px";
let HTMLTable = `
${data.title}
`;
div.innerHTML = HTMLTable;
viewer.cesiumWidget.container.appendChild(div);
let gisPosition = Cesium.Cartesian3.fromDegrees(
data.position[0],
data.position[1],
0
);
//实时更新位置
viewer.scene.postRender.addEventListener(() => {
const canvasHeight = viewer.scene.canvas.height;
const windowPosition = new Cesium.Cartesian2();
Cesium.SceneTransforms.wgs84ToWindowCoordinates(
viewer.scene,
gisPosition,
windowPosition
);
div.style.bottom = canvasHeight - windowPosition.y + "px";
const elWidth = div.offsetWidth;
div.style.left = windowPosition.x - elWidth / 2 + "px";
}, this);
}
现在我们自定义的标签已经能跟随地球移动了，但是我们在转动的过程中可以发现，当目标点位已经到地球背面时label标签并没有消失，下面我们来完美解决他
addDynamicLabel(data){
let div = document.createElement("div");
div.id = data.id;
div.style.position = "absolute";
div.style.width = "100px";
div.style.height = "30px";
let HTMLTable = `
${data.title}
`;
div.innerHTML = HTMLTable;
viewer.cesiumWidget.container.appendChild(div);
let gisPosition = Cesium.Cartesian3.fromDegrees(
data.position[0],
data.position[1],
0
);
//实时更新位置
viewer.scene.postRender.addEventListener(() => {
const canvasHeight = viewer.scene.canvas.height;
const windowPosition = new Cesium.Cartesian2();
Cesium.SceneTransforms.wgs84ToWindowCoordinates(
viewer.scene,
gisPosition,
windowPosition
);
div.style.bottom = canvasHeight - windowPosition.y + "px";
const elWidth = div.offsetWidth;
div.style.left = windowPosition.x - elWidth / 2 + "px";
//解决滚动不隐藏问题
const camerPosition = viewer.camera.position;
let height = viewer.scene.globe.ellipsoid.cartesianToCartographic(camerPosition).height;
height += viewer.scene.globe.ellipsoid.maximumRadius;
console.log(camerPosition,val.position )
if((!(Cesium.Cartesian3.distance(camerPosition,gisPosition ) > height))&&viewer.camera.positionCartographic.height<50000000){
div.style.display = "block"
}else{
div.style.display = "none"
}
}, this);
}
接下来就差用css3调样式了，其余的基本上解决完，但是我们先不要急于调样式，在我们开发过程中不止一处会用到，所以我们先来对其进行封装一下（最中的炫酷效果我也放到封装栏里面进行讲解 ）
# 封装
这里我们用es6中class 进行封装，我们先创建一个js文件divLabel.js
/**
* @descripion:
* @param {Viewer} viewer
* @param {Cartesian2} position
* @param {String} title
* @param {String} id
* @return {*}
*/
export default class DivLabel{
constructor(val) {
this.viewer = val.viewer;
this.height = val.height;
this.position = Cesium.Cartesian3.fromDegrees(
val.position[0],
val.position[1],
val.height
);
this.div = document.createElement("div");
this.addLabel(val);
}
addLabel(val) {
this.div.id = val.id;
this.div.style.position = "absolute";
this.div.style.width = "100px";
this.div.style.height = "30px";
let divHTML = `${val.title}`
this.div.innerHTML = divHTML;
this.viewer.cesiumWidget.container.appendChild(this.div);
this.addPostRender()
}
addPostRender() {
this.viewer.scene.postRender.addEventListener(this.postRender, this);
}
postRender() {
const canvasHeight = this.viewer.scene.canvas.height;
const windowPosition = new Cesium.Cartesian2();
Cesium.SceneTransforms.wgs84ToWindowCoordinates(
this.viewer.scene,
this.position,
windowPosition
);
this.div.style.bottom = canvasHeight - windowPosition.y + "px";
const elWidth = this.div.offsetWidth ;
this.div.style.left = windowPosition.x - elWidth / 2 + "px";
const camerPosition = this.viewer.camera.position;
let height = this.viewer.scene.globe.ellipsoid.cartesianToCartographic(camerPosition).height;
height += this.viewer.scene.globe.ellipsoid.maximumRadius;
if((!(Cesium.Cartesian3.distance(camerPosition,this.position) > height))&&this.viewer.camera.positionCartographic.height<50000000){
this.div.style.display = "block"
}else{
this.div.style.display = "none"
}
}
}
直接调用就可以了，但是我们这样加载dom貌似有点不完美，不便于维护，到最后飞的满天都是。我们可以看一线VUE官网中可以用Vue.extend + $mount，构造器来创建子类。接下来我们先创建一个vue文件取名为label.vue，用来存放我们的标签及样式
{{ title }}
接下来我们改造刚才拿class 封装的divLabel.js文件，将label.vue引进来
/**
* @descripion:
* @param {Viewer} viewer
* @param {Cartesian2} position
* @param {String} title
* @param {String} id
* @return {*}
*/
import Vue from "vue";
import Label from "./label.vue";
let WindowVm = Vue.extend(Label);
export default class DivLabel{
constructor(val) {
this.viewer = val.viewer;
this.height = val.height;
this.position = Cesium.Cartesian3.fromDegrees(
val.position[0],
val.position[1],
val.height
);
let title = val.title;
let id = val.id
this.vmInstance = new WindowVm({
propsData: {
title,
id
}
}).$mount(); //根据模板创建一个面板
val.viewer.cesiumWidget.container.appendChild(this.vmInstance.$el); //将字符串模板生成的内容添加到DOM上
this.addPostRender();
}
//添加场景事件
addPostRender() {
this.viewer.scene.postRender.addEventListener(this.postRender, this);
}
//场景渲染事件 实时更新窗口的位置 使其与笛卡尔坐标一致
postRender() {
if (!this.vmInstance.$el || !this.vmInstance.$el.style) return;
const canvasHeight = this.viewer.scene.canvas.height;
const windowPosition = new Cesium.Cartesian2();
Cesium.SceneTransforms.wgs84ToWindowCoordinates(
this.viewer.scene,
this.position,
windowPosition
);
this.vmInstance.$el.style.bottom =
canvasHeight - windowPosition.y + this.height + "px";
const elWidth = this.vmInstance.$el.offsetWidth;
this.vmInstance.$el.style.left = windowPosition.x - elWidth / 2 + "px";
const camerPosition = this.viewer.camera.position;
let height = this.viewer.scene.globe.ellipsoid.cartesianToCartographic(camerPosition).height;
height += this.viewer.scene.globe.ellipsoid.maximumRadius;
if((!(Cesium.Cartesian3.distance(camerPosition,this.position) > height))&&this.viewer.camera.positionCartographic.height<50000000){
this.vmInstance.$el.style.display = "block";
}else{
this.vmInstance.$el.style.display = "none";
}
}
}
最后我们只需在我们页面中引用即可
import DivLabel from './divLabel.js'
addDivLabel() {
let val = {
viewer:this.$store.state.viewer,
position:[124.54035, 38.92146],
height:0,
title:'CL标签',
id:'210201025'
}
let label = new DivLabel(val)
}
至此我们我们的效果就与开始图中的效果一摸一样了。大功告成
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原文链接：https://blog.csdn.net/weixin_46730573/article/details/119061305