Iau2000Orientation.js

/*global define*/
define([
        './defined',
        './IauOrientationParameters',
        './JulianDate',
        './Math',
        './TimeConstants'
    ], function(
        defined,
        IauOrientationParameters,
        JulianDate,
        CesiumMath,
        TimeConstants) {
    "use strict";

    /**
     * This is a collection of the orientation information available for central bodies.
     * The data comes from the Report of the IAU/IAG Working Group on Cartographic
     * Coordinates and Rotational Elements: 2000.
     * @exports Iau2000Orientation
     *
     * @private
     */
    var Iau2000Orientation = {};

    var TdtMinusTai = 32.184;
    var J2000d = 2451545.0;

    var c1 = -0.0529921;
    var c2 = -0.1059842;
    var c3 = 13.0120009;
    var c4 = 13.3407154;
    var c5 = 0.9856003;
    var c6 = 26.4057084;
    var c7 = 13.0649930;
    var c8 = 0.3287146;
    var c9 = 1.7484877;
    var c10 = -0.1589763;
    var c11 = 0.0036096;
    var c12 = 0.1643573;
    var c13 = 12.9590088;

    /**
     * Compute the orientation parameters for the Moon.
     *
     * @param {JulianDate} [date=new JulianDate()] The date to evaluate the parameters.
     * @param {IauOrientationParameters} [result] The object onto which to store the result.
     *
     * @returns {IauOrientationParameters} The modified result parameter or a new instance representing the orientation of the Earth's Moon.
     */
    Iau2000Orientation.ComputeMoon = function(date, result) {
        if (!defined(date)) {
            date = new JulianDate();
        }

        var dateTT = date.addSeconds(TdtMinusTai);
        var d = dateTT.getTotalDays() - J2000d;
        var T = d / TimeConstants.DAYS_PER_JULIAN_CENTURY;

        var E1 = (125.045 + c1 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E2 = (250.089 + c2 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E3 = (260.008 + c3 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E4 = (176.625 + c4 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E5 = (357.529 + c5 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E6 = (311.589 + c6 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E7 = (134.963 + c7 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E8 = (276.617 + c8 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E9 = (34.226 + c9 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E10 = (15.134 + c10 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E11 = (119.743 + c11 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E12 = (239.961 + c12 * d) * CesiumMath.RADIANS_PER_DEGREE;
        var E13 = (25.053 + c13 * d) * CesiumMath.RADIANS_PER_DEGREE;

        var sinE1 = Math.sin(E1);
        var sinE2 = Math.sin(E2);
        var sinE3 = Math.sin(E3);
        var sinE4 = Math.sin(E4);
        var sinE5 = Math.sin(E5);
        var sinE6 = Math.sin(E6);
        var sinE7 = Math.sin(E7);
        var sinE8 = Math.sin(E8);
        var sinE9 = Math.sin(E9);
        var sinE10 = Math.sin(E10);
        var sinE11 = Math.sin(E11);
        var sinE12 = Math.sin(E12);
        var sinE13 = Math.sin(E13);

        var cosE1 = Math.cos(E1);
        var cosE2 = Math.cos(E2);
        var cosE3 = Math.cos(E3);
        var cosE4 = Math.cos(E4);
        var cosE5 = Math.cos(E5);
        var cosE6 = Math.cos(E6);
        var cosE7 = Math.cos(E7);
        var cosE8 = Math.cos(E8);
        var cosE9 = Math.cos(E9);
        var cosE10 = Math.cos(E10);
        var cosE11 = Math.cos(E11);
        var cosE12 = Math.cos(E12);
        var cosE13 = Math.cos(E13);

        var rightAscension = (269.9949 + 0.0031 * T - 3.8787 * sinE1 - 0.1204 * sinE2 +
            0.0700 * sinE3 - 0.0172 * sinE4 + 0.0072 * sinE6 -
            0.0052 * sinE10 + 0.0043 * sinE13) *
            CesiumMath.RADIANS_PER_DEGREE;
        var declination = (66.5392 + 0.013 * T + 1.5419 * cosE1 + 0.0239 * cosE2 -
            0.0278 * cosE3 + 0.0068 * cosE4 - 0.0029 * cosE6 +
            0.0009 * cosE7 + 0.0008 * cosE10 - 0.0009 * cosE13) *
            CesiumMath.RADIANS_PER_DEGREE;
        var rotation = (38.3213 + 13.17635815 * d - 1.4e-12 * d * d + 3.5610 * sinE1 +
            0.1208 * sinE2 - 0.0642 * sinE3 + 0.0158 * sinE4 +
            0.0252 * sinE5 - 0.0066 * sinE6 - 0.0047 * sinE7 -
            0.0046 * sinE8 + 0.0028 * sinE9 + 0.0052 * sinE10 +
            0.004 * sinE11 + 0.0019 * sinE12 - 0.0044 * sinE13) *
            CesiumMath.RADIANS_PER_DEGREE;

        var rotationRate = ((13.17635815 - 1.4e-12 * (2.0 * d)) +
            3.5610 * cosE1 * c1 +
            0.1208 * cosE2*c2 - 0.0642 * cosE3*c3 + 0.0158 * cosE4*c4 +
            0.0252 * cosE5*c5 - 0.0066 * cosE6*c6 - 0.0047 * cosE7*c7 -
            0.0046 * cosE8*c8 + 0.0028 * cosE9*c9 + 0.0052 * cosE10*c10 +
            0.004 * cosE11*c11 + 0.0019 * cosE12*c12 - 0.0044 * cosE13*c13) /
            86400.0 * CesiumMath.RADIANS_PER_DEGREE;

        if (!defined(result)) {
            result = new IauOrientationParameters();
        }

        result.rightAscension = rightAscension;
        result.declination = declination;
        result.rotation = rotation;
        result.rotationRate = rotationRate;

        return result;
    };

    return Iau2000Orientation;
});