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

        json.bottom = obj.bottom;
        json.far = obj.far;
        json.left = obj.left;
        json.near = obj.near;
        json.right = obj.right;
        json.top = obj.top;
        json.view = obj.view;
        json.zoom = obj.zoom;

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