【threejs】透视相机，实现相机根据模型大小自适应，将模型放置在视角内

透视相机，实现相机根据模型大小自适应，将模型放置在视角内

 const box3_2 = new THREE.Box3().setFromObject(object);   //新建一个Box3包裹盒把模型包裹起来
        const boxSize = box3_2.getSize(new THREE.Vector3()).length();  //综合计算出模型的长度值，利用它设置相机位置
        boxCenter = box3_2.getCenter(new THREE.Vector3());
        const fov = camera.fov * (Math.PI / 180);
        const cameraZ = boxSize / 2 / Math.tan(fov / 2);
        camera.position.z = cameraZ;