Cesium-Prequel/Source/DataSources/VelocityOrientationProperty.js

import Cartesian3 from "../Core/Cartesian3.js";
import defaultValue from "../Core/defaultValue.js";
import defined from "../Core/defined.js";
import Ellipsoid from "../Core/Ellipsoid.js";
import Event from "../Core/Event.js";
import Matrix3 from "../Core/Matrix3.js";
import Quaternion from "../Core/Quaternion.js";
import Transforms from "../Core/Transforms.js";
import Property from "./Property.js";
import VelocityVectorProperty from "./VelocityVectorProperty.js";

/**
 * A {@link Property} which evaluates to a {@link Quaternion} rotation
 * based on the velocity of the provided {@link PositionProperty}.
 *
 * @alias VelocityOrientationProperty
 * @constructor
 *
 * @param {PositionProperty} [position] The position property used to compute the orientation.
 * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid used to determine which way is up.
 *
 * @example
 * //Create an entity with position and orientation.
 * var position = new Cesium.SampledProperty();
 * position.addSamples(...);
 * var entity = viewer.entities.add({
 *   position : position,
 *   orientation : new Cesium.VelocityOrientationProperty(position)
 * }));
 */
function VelocityOrientationProperty(position, ellipsoid) {
  this._velocityVectorProperty = new VelocityVectorProperty(position, true);
  this._subscription = undefined;
  this._ellipsoid = undefined;
  this._definitionChanged = new Event();

  this.ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

  var that = this;
  this._velocityVectorProperty.definitionChanged.addEventListener(function () {
    that._definitionChanged.raiseEvent(that);
  });
}

Object.defineProperties(VelocityOrientationProperty.prototype, {
  /**
   * Gets a value indicating if this property is constant.
   * @memberof VelocityOrientationProperty.prototype
   *
   * @type {Boolean}
   * @readonly
   */
  isConstant: {
    get: function () {
      return Property.isConstant(this._velocityVectorProperty);
    },
  },
  /**
   * Gets the event that is raised whenever the definition of this property changes.
   * @memberof VelocityOrientationProperty.prototype
   *
   * @type {Event}
   * @readonly
   */
  definitionChanged: {
    get: function () {
      return this._definitionChanged;
    },
  },
  /**
   * Gets or sets the position property used to compute orientation.
   * @memberof VelocityOrientationProperty.prototype
   *
   * @type {Property|undefined}
   */
  position: {
    get: function () {
      return this._velocityVectorProperty.position;
    },
    set: function (value) {
      this._velocityVectorProperty.position = value;
    },
  },
  /**
   * Gets or sets the ellipsoid used to determine which way is up.
   * @memberof VelocityOrientationProperty.prototype
   *
   * @type {Property|undefined}
   */
  ellipsoid: {
    get: function () {
      return this._ellipsoid;
    },
    set: function (value) {
      var oldValue = this._ellipsoid;
      if (oldValue !== value) {
        this._ellipsoid = value;
        this._definitionChanged.raiseEvent(this);
      }
    },
  },
});

var positionScratch = new Cartesian3();
var velocityScratch = new Cartesian3();
var rotationScratch = new Matrix3();

/**
 * Gets the value of the property at the provided time.
 *
 * @param {JulianDate} [time] The time for which to retrieve the value.
 * @param {Quaternion} [result] The object to store the value into, if omitted, a new instance is created and returned.
 * @returns {Quaternion} The modified result parameter or a new instance if the result parameter was not supplied.
 */
VelocityOrientationProperty.prototype.getValue = function (time, result) {
  var velocity = this._velocityVectorProperty._getValue(
    time,
    velocityScratch,
    positionScratch
  );

  if (!defined(velocity)) {
    return undefined;
  }

  Transforms.rotationMatrixFromPositionVelocity(
    positionScratch,
    velocity,
    this._ellipsoid,
    rotationScratch
  );
  return Quaternion.fromRotationMatrix(rotationScratch, result);
};

/**
 * Compares this property to the provided property and returns
 * <code>true</code> if they are equal, <code>false</code> otherwise.
 *
 * @param {Property} [other] The other property.
 * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
 */
VelocityOrientationProperty.prototype.equals = function (other) {
  return (
    this === other || //
    (other instanceof VelocityOrientationProperty &&
      Property.equals(
        this._velocityVectorProperty,
        other._velocityVectorProperty
      ) &&
      (this._ellipsoid === other._ellipsoid ||
        this._ellipsoid.equals(other._ellipsoid)))
  );
};
export default VelocityOrientationProperty;