Compute sun and moon positions

CHANGES.md

@@ -29,6 +29,7 @@ Beta Releases
          });
    * `CzmlCartographic` has been removed and all cartographic values are converted to Cartesian internally during CZML processing.  This improves performance and fixes interpolation of cartographic source data.  The Cartographic representation can still be retrieved if needed.
    * Removed `ComplexConicSensorVolume`, which was not documented and did not work on most platforms.  It will be brought back in a future release.  This does not affect CZML, which uses a custom sensor to approximate a complex conic.
+   * Replaced `computeSunPosition` with `Simon1994PlanetaryPosition`, which has functions to calculate the position of the sun and the moon more accurately.
 * Added wide polylines that work with and without ANGLE.
 * Polylines now use materials to describe their surface appearance. See the [Fabric](https://github.com/AnalyticalGraphicsInc/cesium/wiki/Fabric) wiki page for more details on how to create materials.
 * Added new `PolylineOutline`, `PolylineArrow`, and `Fade` materials.

Source/Core/Cartesian3.js

@@ -926,5 +926,18 @@ define([
         return Cartesian3.cross(this, right, result);
     };
 
+    /**
+     * Produces a Cartesian3 representing this instance which results from rotating
+     * the original axes used to represent this instance by the provided Quaternion rotation.
+     * @memberof Cartesian3
+     *
+     * @param {Quaternion}
+     * @return {Cartesian3} The result of the rotation
+     *
+     */
+    Cartesian3.prototype.rotate = function(quaternion, result) {
+        return Cartesian3.rotate(this, quaternion, result);
+    };
+
     return Cartesian3;
 });

Source/Core/Math.js

@@ -397,7 +397,7 @@ define([
     };
 
     /**
-     * Alters the value of input x such that <code>-CesiumMath.PI</code> <= x <= <code>CesiumMath.PI</code>
+     * Produces an angle in the range 0 <= angle <= 2Pi which is equivalent to the provided angle.
      * @param {Number} angle in radians
      * @return {Number} The angle in the range ()<code>-CesiumMath.PI</code>, <code>CesiumMath.PI</code>).
      */
@@ -417,6 +417,18 @@ define([
         return x > pi ? pi : x;
     };
 
+    /**
+     * Produces an angle in the range -Pi <= angle <= Pi which is equivalent to the provided angle.
+     * @param {Number} angle in radians
+     * @return {Number} The angle in the range (0 , <code>CesiumMath.TWO_PI</code>).
+     */
+    CesiumMath.zeroToTwoPi = function(x) {
+        var value = x % CesiumMath.TWO_PI;
+        // We do a second modules here if we add 2Pi to ensure that we don't have any numerical issues with very
+        // small negative values.
+        return (value < 0.0) ? (value + CesiumMath.TWO_PI) % CesiumMath.TWO_PI : value;
+    };
+
     /**
      * DOC_TBA
      */