cesium获取场景

提供一些常见的场景数据获取方法。

1、获取屏幕中心点坐标：

//格式化 数字 小数位数
const formatNum = (num:number, digits: number) =>{
    return Number(Number(num).toFixed(digits || 0));
};
//取屏幕中心点坐标
const pickCenterPoint = (scene:any) => {
    let canvas = scene.canvas;
    let center = new Cesium.Cartesian2(canvas.clientWidth / 2, canvas.clientHeight / 2);
    let ray = scene.camera.getPickRay(center);
    let target = scene.globe.pick(ray, scene);
    if (!target) target = scene.camera.pickEllipsoid(center);
    return target;
};
//提取屏幕中心点坐标
const getCenter = (viewer:any) =>{
    let position = pickCenterPoint(viewer.scene);
    if (!position) return null;
    let carto = Cesium.Cartographic.fromCartesian(position);
    let result:any = {};
    result.lat = formatNum(Cesium.Math.toDegrees(carto.latitude), 6);
    result.lon = formatNum(Cesium.Math.toDegrees(carto.longitude), 6);
    result.height = formatNum(carto.height, 2);
    return result;
}

2、获取相机高度：

const getHeight = (viewer) => { 
    let scene = viewer.scene; 
    let ellipsoid = scene.globe.ellipsoid; 
    let height = ellipsoid.cartesianToCartographic(viewer.camera.position).height; 
    return height; 
};

3、获取相机位置：

//获取相机位置 
const cameraRelay = () => { 
    //位置 
    let position = viewer.scene.camera.position 
    // 视高 km 
    let alt = (viewer.camera.positionCartographic.height / 1000).toFixed(2); 
   // 方位角  
    let heading = Cesium.Math.toDegrees(viewer.camera.heading).toFixed(2); 
    // 俯仰角 
    let pitch = Cesium.Math.toDegrees(viewer.camera.pitch).toFixed(2); 
    // 翻滚角 
    let roll = Cesium.Math.toDegrees(viewer.camera.roll).toFixed(2); 
    let cameraStr = `视高：${alt}km  方位角：${heading}° 俯仰角：${pitch}° 翻滚角：${roll}°`;
    return cameraStr;
}; 
//监听相机位置获取事件 
const getCamera = () => { 
    viewer.camera.changed.addEventListener(cameraRelay); 
};

4、获取当前场景范围：

//获取当前场景范围
const getCurrentExtent = (viewer:any) =>{
    // 范围对象默认值--中国区域
   let extent:any = {
        xmin: 70,
        xmax: 140,
        ymin: 0,
        ymax: 55,
        height: 0
    };
    // 得到当前三维场景
    let scene = viewer.scene;
    // 得到当前三维场景的椭球体
    let ellipsoid = scene.globe.ellipsoid;
    let canvas = scene.canvas;
    // canvas左上角
    let car3_lt = viewer.camera.pickEllipsoid(new Cesium.Cartesian2(0, 0), ellipsoid);
    if (car3_lt) {
        // 在椭球体上
        let carto_lt = ellipsoid.cartesianToCartographic(car3_lt);
        extent.xmin = Cesium.Math.toDegrees(carto_lt.longitude);
        extent.ymax = Cesium.Math.toDegrees(carto_lt.latitude);
        extent.height = Math.max(extent.height, carto_lt.height);
    } else {
        // 不在椭球体上 
        let xMax = canvas.width / 2;
        let yMax = canvas.height / 2;
        let car3_lt2;
        // 这里每次10像素递加，一是10像素相差不大，二是为了提高程序运行效率
        for (let yIdx = 0; yIdx <= yMax; yIdx += 10) {
            let xIdx = yIdx <= xMax ? yIdx : xMax;
            car3_lt2 = viewer.camera.pickEllipsoid(new Cesium.Cartesian2(xIdx, yIdx), ellipsoid);
            if (car3_lt2) break;
        }
        if (car3_lt2) {
            let carto_lt = ellipsoid.cartesianToCartographic(car3_lt2);
            extent.xmin = Cesium.Math.toDegrees(carto_lt.longitude);
            extent.ymax = Cesium.Math.toDegrees(carto_lt.latitude);
            extent.height = Math.max(extent.height, carto_lt.height);
        }
    }
    // canvas右下角
    let car3_rb = viewer.camera.pickEllipsoid(new Cesium.Cartesian2(canvas.width, canvas.height), ellipsoid);
 	if (car3_rb) {
        // 在椭球体上
        let carto_rb = ellipsoid.cartesianToCartographic(car3_rb);
        extent.xmax = Cesium.Math.toDegrees(carto_rb.longitude);
        extent.ymin = Cesium.Math.toDegrees(carto_rb.latitude);
        extent.height = Math.max(extent.height, carto_rb.height);
    } else {
        // 不在椭球体上
        let xMax = canvas.width / 2;
        let yMax = canvas.height / 2;

        let car3_rb2;
        // 这里每次10像素递减，一是10像素相差不大，二是为了提高程序运行效率
        for (let yIdx = canvas.height; yIdx >= yMax; yIdx -= 10) {
            let xIdx = yIdx >= xMax ? yIdx : xMax;
            car3_rb2 = viewer.camera.pickEllipsoid(new Cesium.Cartesian2(xIdx, yIdx), ellipsoid);
            if (car3_rb2) break;
        }
        if (car3_rb2) {
            let carto_rb = ellipsoid.cartesianToCartographic(car3_rb2);
            extent.xmax = Cesium.Math.toDegrees(carto_rb.longitude);
            extent.ymin = Cesium.Math.toDegrees(carto_rb.latitude);
            extent.height = Math.max(extent.height, carto_rb.height);
        }
    }
    return extent; 
};

项目地址：github.com/DLFouge/vue…

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