/*
 * @Description: 相机绕点旋转
 * @Version: 1.0
 * @Author: joy
 * @Date: 2023-04-11 21:42:26
 * @LastEditors: joy
 * @LastEditTime: 2023-04-12 16:32:25
 */
class AroundPoint {
	constructor(viewer, amount, position) {
		this._viewer = viewer;
		this._amount = amount;
		this._position = position;
		this._range = this._viewer.camera.positionCartographic.height;
	}

	_bindEvent() {
		let _self = this;

		this._viewer.clock.onTick.addEventListener(this._aroundPoint, this);
		//监听点击事件
		var handler = new Cesium.ScreenSpaceEventHandler(this._viewer.scene.canvas);
		handler.setInputAction(function(click) {
			_self.stop();
		}, Cesium.ScreenSpaceEventType.LEFT_DOWN);
	}

	_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;
		let range = this._range;

		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,
				range,
			)
		)
	}
}

export default AroundPoint