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

        json.bias = obj.bias;
        json.camera = new CamerasSerializer().toJSON(obj.camera);
        json.map = !obj.map ? null : new WebGLRenderTargetSerializer().toJSON(obj.map);
        json.mapSize = obj.mapSize;
        json.radius = obj.radius;

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