TDGameClient3D/assets/scripts/engines/cameras/CameraFitWidth.ts

import { _decorator, Component, Node, CameraComponent, view } from 'cc';
const { ccclass, property } = _decorator;

@ccclass('CameraFitWidth')
export class CameraFitWidth extends Component {

    private camera!:CameraComponent;

    private _defaultTanFov!: number;

    // LIFE-CYCLE CALLBACKS:

    onLoad () {
        this.camera = this.getComponent(CameraComponent);
        this._defaultTanFov = Math.tan(this.camera.fov / 180 * Math.PI);
        this.updateFov();
        window.addEventListener('resize', this.updateFov);
    }

    updateFov = () => {
        let tan2 = view.getVisibleSize().height / view.getDesignResolutionSize().height * this._defaultTanFov;
        this.camera.fov = Math.atan(tan2) / Math.PI * 180;
    }

    onDestroy() {
        window.removeEventListener('resize', this.updateFov);
    }
}