Add cartographic to cartesian3 method

CHANGES.md

@@ -40,6 +40,7 @@ Change Log
 * Fixed sandcastle Particle System example for better visual [#6132](https://github.com/AnalyticalGraphicsInc/cesium/pull/6132)
 * Fixed camera movement and look functions for 2D mode [#5884](https://github.com/AnalyticalGraphicsInc/cesium/issues/5884)
 * Fixed discrepancy between default value used and commented value for default value for halfAxes of OrientedBoundingBox. [#6147](https://github.com/AnalyticalGraphicsInc/cesium/pull/6147)
+* Added `Cartographic.toCartesian` to convert from Cartographic to Cartesian3. [#6163](https://github.com/AnalyticalGraphicsInc/cesium/pull/6163)
 
 ### 1.41 - 2018-01-02
 

Source/Core/Cartographic.js

@@ -146,6 +146,23 @@ define([
         return result;
     };
 
+    /**
+     * Creates a new Cartesian3 instance from a Cartographic input. The values in the inputted
+     * object should be in radians.
+     *
+     * @param {Cartographic} cartographic Input to be converted into a Cartesian3 output.
+     * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
+     * @param {Cartesian3} [result] The object onto which to store the result.
+     * @returns {Cartesian3} The position
+     */
+    Cartographic.toCartesian = function(cartographic, ellipsoid, result) {
+        //>>includeStart('debug', pragmas.debug);
+        Check.defined('cartographic', cartographic);
+        //>>includeEnd('debug');
+
+        return Cartesian3.fromRadians(cartographic.longitude, cartographic.latitude, cartographic.height, ellipsoid, result);
+    };
+
     /**
      * Duplicates a Cartographic instance.
      *

Specs/Core/CartographicSpec.js

@@ -27,6 +27,16 @@ defineSuite([
         expect(c.height).toEqual(3);
     });
 
+    it('toCartesian conversion from Cartographic input to Cartesian3 output', function(){
+        var lon = CesiumMath.toRadians(150);
+        var lat = CesiumMath.toRadians(-40);
+        var height = 100000;
+        var ellipsoid = Ellipsoid.WGS84;
+        var actual = Cartographic.toCartesian(new Cartographic(lon, lat, height));
+        var expected = ellipsoid.cartographicToCartesian(new Cartographic(lon, lat, height));
+        expect(actual).toEqual(expected);
+    });
+
     it('fromRadians works without a result parameter', function() {
         var c = Cartographic.fromRadians(Math.PI/2, Math.PI/4, 100.0);
         expect(c.longitude).toEqual(Math.PI/2);