toJSON(obj) {
        var json = CameraSerializer.prototype.toJSON.call(this, obj);

        json.aspect = obj.aspect;
        json.far = obj.far;
        json.filmGauge = obj.filmGauge;
        json.filmOffset = obj.filmOffset;
        json.focus = obj.focus;
        json.fov = obj.fov;
        json.near = obj.near;
        json.view = obj.view;
        json.zoom = obj.zoom;

        return json;
    }
PerspectiveCameraSerializer
@author tengge / https://github.com/tengge1