cesium实现相机绕点旋转效果

Cesium实战系列文章总目录： 传送门

1. 实现效果

2. 实现方法

2.1 实现思路

相机绕点旋转，即相机指向中心点不变，不断更改heading属性即可，使用Camera类的lookAt方法，API：传送门

2.2 具体代码

（1）代码调用
引入下面的核心js后，简单调用即可。

 let aroundPoint = new AroundPoint(viewer, 0.2, new Cesium.Cartesian3.fromDegrees(103.62416890925606, 28.782654034074834, 1300));

 aroundPoint.start();

（2）核心代码

/*
 * @Description: 相机绕点旋转
 * @Version: 1.0
 * @Author: Julian
 * @Date: 2022-05-06 21:42:26
 * @LastEditors: Julian
 * @LastEditTime: 2022-05-08 16:32:25
 */
class AroundPoint {
    constructor(viewer, amount, position) {
        this._viewer = viewer;
        this._amount = amount;
        this._position = position;
    }

    _bindEvent() {
        this._viewer.clock.onTick.addEventListener(this._aroundPoint, this);
    }

    _unbindEvent() {
        this._viewer.camera.lookAtTransform(Cesium.Matrix4.IDENTITY);
        this._viewer.clock.onTick.removeEventListener(this._aroundPoint, this);
    }

    start() {
        this._viewer.clock.shouldAnimate = true;
        this._unbindEvent();
        this._bindEvent();
        return this;
    }

    stop() {
        this._unbindEvent();
        return this;
    }

    // 相机绕点旋转函数
    _aroundPoint() {
        let heading = this._viewer.camera.heading;
        let pitch = this._viewer.camera.pitch;


        heading += Cesium.Math.toRadians(this._amount);
        if (heading >= Math.PI * 2 || heading <= -Math.PI * 2) {
            heading = 0;
        }

        this._viewer.camera.lookAt(
            this._position,
            new Cesium.HeadingPitchRange(
                heading,
                pitch,
                5000.0,
            )
        )
    }
}