SampledPositionProperty.js

define([
        '../Core/Cartesian3',
        '../Core/Check',
        '../Core/defaultValue',
        '../Core/defined',
        '../Core/defineProperties',
        '../Core/DeveloperError',
        '../Core/Event',
        '../Core/ReferenceFrame',
        './PositionProperty',
        './Property',
        './SampledProperty'
    ], function(
        Cartesian3,
        Check,
        defaultValue,
        defined,
        defineProperties,
        DeveloperError,
        Event,
        ReferenceFrame,
        PositionProperty,
        Property,
        SampledProperty) {
    'use strict';

    /**
     * A {@link SampledProperty} which is also a {@link PositionProperty}.
     *
     * @alias SampledPositionProperty
     * @constructor
     *
     * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
     * @param {Number} [numberOfDerivatives=0] The number of derivatives that accompany each position; i.e. velocity, acceleration, etc...
     */
    function SampledPositionProperty(referenceFrame, numberOfDerivatives) {
        numberOfDerivatives = defaultValue(numberOfDerivatives, 0);

        var derivativeTypes;
        if (numberOfDerivatives > 0) {
            derivativeTypes = new Array(numberOfDerivatives);
            for (var i = 0; i < numberOfDerivatives; i++) {
                derivativeTypes[i] = Cartesian3;
            }
        }

        this._numberOfDerivatives = numberOfDerivatives;
        this._property = new SampledProperty(Cartesian3, derivativeTypes);
        this._definitionChanged = new Event();
        this._referenceFrame = defaultValue(referenceFrame, ReferenceFrame.FIXED);

        this._property._definitionChanged.addEventListener(function() {
            this._definitionChanged.raiseEvent(this);
        }, this);
    }

    defineProperties(SampledPositionProperty.prototype, {
        /**
         * Gets a value indicating if this property is constant.  A property is considered
         * constant if getValue always returns the same result for the current definition.
         * @memberof SampledPositionProperty.prototype
         *
         * @type {Boolean}
         * @readonly
         */
        isConstant : {
            get : function() {
                return this._property.isConstant;
            }
        },
        /**
         * Gets the event that is raised whenever the definition of this property changes.
         * The definition is considered to have changed if a call to getValue would return
         * a different result for the same time.
         * @memberof SampledPositionProperty.prototype
         *
         * @type {Event}
         * @readonly
         */
        definitionChanged : {
            get : function() {
                return this._definitionChanged;
            }
        },
        /**
         * Gets the reference frame in which the position is defined.
         * @memberof SampledPositionProperty.prototype
         * @type {ReferenceFrame}
         * @default ReferenceFrame.FIXED;
         */
        referenceFrame : {
            get : function() {
                return this._referenceFrame;
            }
        },
        /**
         * Gets the degree of interpolation to perform when retrieving a value.
         * @memberof SampledPositionProperty.prototype
         *
         * @type {Number}
         * @default 1
         */
        interpolationDegree : {
            get : function() {
                return this._property.interpolationDegree;
            }
        },
        /**
         * Gets the interpolation algorithm to use when retrieving a value.
         * @memberof SampledPositionProperty.prototype
         *
         * @type {InterpolationAlgorithm}
         * @default LinearApproximation
         */
        interpolationAlgorithm : {
            get : function() {
                return this._property.interpolationAlgorithm;
            }
        },
        /**
         * The number of derivatives contained by this property; i.e. 0 for just position, 1 for velocity, etc.
         * @memberof SampledPositionProperty.prototype
         *
         * @type {Boolean}
         * @default false
         */
        numberOfDerivatives : {
            get : function() {
                return this._numberOfDerivatives;
            }
        },
        /**
         * Gets or sets the type of extrapolation to perform when a value
         * is requested at a time after any available samples.
         * @memberof SampledPositionProperty.prototype
         * @type {ExtrapolationType}
         * @default ExtrapolationType.NONE
         */
        forwardExtrapolationType : {
            get : function() {
                return this._property.forwardExtrapolationType;
            },
            set : function(value) {
                this._property.forwardExtrapolationType = value;
            }
        },
        /**
         * Gets or sets the amount of time to extrapolate forward before
         * the property becomes undefined.  A value of 0 will extrapolate forever.
         * @memberof SampledPositionProperty.prototype
         * @type {Number}
         * @default 0
         */
        forwardExtrapolationDuration : {
            get : function() {
                return this._property.forwardExtrapolationDuration;
            },
            set : function(value) {
                this._property.forwardExtrapolationDuration = value;
            }
        },
        /**
         * Gets or sets the type of extrapolation to perform when a value
         * is requested at a time before any available samples.
         * @memberof SampledPositionProperty.prototype
         * @type {ExtrapolationType}
         * @default ExtrapolationType.NONE
         */
        backwardExtrapolationType : {
            get : function() {
                return this._property.backwardExtrapolationType;
            },
            set : function(value) {
                this._property.backwardExtrapolationType = value;
            }
        },
        /**
         * Gets or sets the amount of time to extrapolate backward
         * before the property becomes undefined.  A value of 0 will extrapolate forever.
         * @memberof SampledPositionProperty.prototype
         * @type {Number}
         * @default 0
         */
        backwardExtrapolationDuration : {
            get : function() {
                return this._property.backwardExtrapolationDuration;
            },
            set : function(value) {
                this._property.backwardExtrapolationDuration = value;
            }
        }
    });

    /**
     * Gets the position at the provided time.
     *
     * @param {JulianDate} time The time for which to retrieve the value.
     * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
     * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
     */
    SampledPositionProperty.prototype.getValue = function(time, result) {
        return this.getValueInReferenceFrame(time, ReferenceFrame.FIXED, result);
    };

    /**
     * Gets the position at the provided time and in the provided reference frame.
     *
     * @param {JulianDate} time The time for which to retrieve the value.
     * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
     * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
     * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
     */
    SampledPositionProperty.prototype.getValueInReferenceFrame = function(time, referenceFrame, result) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('time', time);
        Check.defined('referenceFrame', referenceFrame);
        //>>includeEnd('debug');

        result = this._property.getValue(time, result);
        if (defined(result)) {
            return PositionProperty.convertToReferenceFrame(time, result, this._referenceFrame, referenceFrame, result);
        }
        return undefined;
    };

    /**
     * Sets the algorithm and degree to use when interpolating a position.
     *
     * @param {Object} [options] Object with the following properties:
     * @param {InterpolationAlgorithm} [options.interpolationAlgorithm] The new interpolation algorithm.  If undefined, the existing property will be unchanged.
     * @param {Number} [options.interpolationDegree] The new interpolation degree.  If undefined, the existing property will be unchanged.
     */
    SampledPositionProperty.prototype.setInterpolationOptions = function(options) {
        this._property.setInterpolationOptions(options);
    };

    /**
     * Adds a new sample.
     *
     * @param {JulianDate} time The sample time.
     * @param {Cartesian3} position The position at the provided time.
     * @param {Cartesian3[]} [derivatives] The array of derivative values at the provided time.
     */
    SampledPositionProperty.prototype.addSample = function(time, position, derivatives) {
        var numberOfDerivatives = this._numberOfDerivatives;
        //>>includeStart('debug', pragmas.debug);
        if (numberOfDerivatives > 0 && (!defined(derivatives) || derivatives.length !== numberOfDerivatives)) {
            throw new DeveloperError('derivatives length must be equal to the number of derivatives.');
        }
        //>>includeEnd('debug');
        this._property.addSample(time, position, derivatives);
    };

    /**
     * Adds multiple samples via parallel arrays.
     *
     * @param {JulianDate[]} times An array of JulianDate instances where each index is a sample time.
     * @param {Cartesian3[]} positions An array of Cartesian3 position instances, where each value corresponds to the provided time index.
     * @param {Array[]} [derivatives] An array where each value is another array containing derivatives for the corresponding time index.
     *
     * @exception {DeveloperError} All arrays must be the same length.
     */
    SampledPositionProperty.prototype.addSamples = function(times, positions, derivatives) {
        this._property.addSamples(times, positions, derivatives);
    };

    /**
     * Adds samples as a single packed array where each new sample is represented as a date,
     * followed by the packed representation of the corresponding value and derivatives.
     *
     * @param {Number[]} packedSamples The array of packed samples.
     * @param {JulianDate} [epoch] If any of the dates in packedSamples are numbers, they are considered an offset from this epoch, in seconds.
     */
    SampledPositionProperty.prototype.addSamplesPackedArray = function(packedSamples, epoch) {
        this._property.addSamplesPackedArray(packedSamples, epoch);
    };

    /**
     * Removes a sample at the given time, if present.
     *
     * @param {JulianDate} time The sample time.
     * @returns {Boolean} <code>true</code> if a sample at time was removed, <code>false</code> otherwise.
     */
    SampledPositionProperty.prototype.removeSample = function(time) {
        this._property.removeSample(time);
    };

    /**
     * Removes all samples for the given time interval.
     *
     * @param {TimeInterval} time The time interval for which to remove all samples.
     */
    SampledPositionProperty.prototype.removeSamples = function(timeInterval) {
        this._property.removeSamples(timeInterval);
    };

    /**
     * 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.
     */
    SampledPositionProperty.prototype.equals = function(other) {
        return this === other || //
               (other instanceof SampledPositionProperty &&
                Property.equals(this._property, other._property) && //
                this._referenceFrame === other._referenceFrame);
    };

    return SampledPositionProperty;
});