function Lighting(reflectivityCallback, options) {
      if (options === void 0) {
        options = {};
      }
      this._reflectivityCallback = reflectivityCallback;
      this._options = {};
      options = Object.assign({
        passes: 1,
        emissionThreshold: 100,
        range: 10
      }, options);
      this._lights = {};
      this._reflectivityCache = {};
      this._fovCache = {};
      this.setOptions(options);
    }
Lighting computation, based on a traditional FOV for multiple light sources and multiple passes.