jtBaseApp/node_modules/cesium/Source/DataSources/KmlTourFlyTo.js

import BoundingSphere from "../Core/BoundingSphere.js";
import combine from "../Core/combine.js";
import defined from "../Core/defined.js";
import EasingFunction from "../Core/EasingFunction.js";
/**
 * Transitions the KmlTour to the next destination. This transition is facilitated
 * using a specified flyToMode over a given number of seconds.
 *
 * @alias KmlTourFlyTo
 * @constructor
 *
 * @param {Number} duration entry duration
 * @param {String} flyToMode KML fly to mode: bounce, smooth, etc
 * @param {KmlCamera|KmlLookAt} view KmlCamera or KmlLookAt
 *
 * @see KmlTour
 * @see KmlTourWait
 */
function KmlTourFlyTo(duration, flyToMode, view) {
  this.type = "KmlTourFlyTo";
  this.blocking = true;
  this.activeCamera = null;
  this.activeCallback = null;

  this.duration = duration;
  this.view = view;
  this.flyToMode = flyToMode;
}

/**
 * Play this playlist entry
 *
 * @param {KmlTourFlyTo.DoneCallback} done function which will be called when playback ends
 * @param {Camera} camera Cesium camera
 * @param {Object} [cameraOptions] which will be merged with camera flyTo options. See {@link Camera#flyTo}
 */
KmlTourFlyTo.prototype.play = function (done, camera, cameraOptions) {
  this.activeCamera = camera;
  if (defined(done) && done !== null) {
    const self = this;
    this.activeCallback = function (terminated) {
      delete self.activeCallback;
      delete self.activeCamera;
      done(defined(terminated) ? false : terminated);
    };
  }

  const options = this.getCameraOptions(cameraOptions);
  if (this.view.headingPitchRoll) {
    camera.flyTo(options);
  } else if (this.view.headingPitchRange) {
    const target = new BoundingSphere(this.view.position);
    camera.flyToBoundingSphere(target, options);
  }
};

/**
 * Stop execution of curent entry. Cancel camera flyTo
 */
KmlTourFlyTo.prototype.stop = function () {
  if (defined(this.activeCamera)) {
    this.activeCamera.cancelFlight();
  }
  if (defined(this.activeCallback)) {
    this.activeCallback(true);
  }
};

/**
 * Returns options for {@link Camera#flyTo} or {@link Camera#flyToBoundingSphere}
 * depends on this.view type.
 *
 * @param {Object} cameraOptions options to merge with generated. See {@link Camera#flyTo}
 * @returns {Object} {@link Camera#flyTo} or {@link Camera#flyToBoundingSphere} options
 */
KmlTourFlyTo.prototype.getCameraOptions = function (cameraOptions) {
  let options = {
    duration: this.duration,
  };

  if (defined(this.activeCallback)) {
    options.complete = this.activeCallback;
  }

  if (this.flyToMode === "smooth") {
    options.easingFunction = EasingFunction.LINEAR_NONE;
  }

  if (this.view.headingPitchRoll) {
    options.destination = this.view.position;
    options.orientation = this.view.headingPitchRoll;
  } else if (this.view.headingPitchRange) {
    options.offset = this.view.headingPitchRange;
  }

  if (defined(cameraOptions)) {
    options = combine(options, cameraOptions);
  }
  return options;
};

/**
 * A function that will be executed when the flight completes.
 * @callback KmlTourFlyTo.DoneCallback
 *
 * @param {Boolean} terminated true if {@link KmlTourFlyTo#stop} was
 * called before entry done playback.
 */
export default KmlTourFlyTo;