Arcs (Circle Segments) in Cesium

Cesium polylines follow the curvature of the earth, between two points, by default. How do I make arcs, which go above the ground, like in this example?

http://armsglobe.chromeexperiments.com/

``````function addLines(pointA,pointB){

var earth = Cesium.Ellipsoid.WGS84;
// start and end points on the surface of the earth
var startPoint = earth.cartographicToCartesian(Cesium.Cartographic.fromDegrees(pointA[0][0], pointA[0][1], 0.0));
var endPoint = earth.cartographicToCartesian(Cesium.Cartographic.fromDegrees(pointB[0][0], pointB[0][1], 0.0));

// determine the midpoint (point will be inside the earth)

// move the midpoint to the surface of the earth
earth.scaleToGeodeticSurface(midpointCartesian);

// add some altitude if you want (1000 km in this case)
var midpointCartographic = earth.cartesianToCartographic(midpointCartesian);
midpointCartographic.height = 1000000;
midpointCartesian = earth.cartographicToCartesian(midpointCartographic);

// create a hermite spline that goes through these three points
var hermiteSpline = new Cesium.HermiteSpline( [
{point: startPoint, time: 0.0},
{point: midpointCartesian, time: 0.5},
{point: endPoint, time: 1.0}
]);

// create a 20 point polyline that follows the spline
var polylinePoints = [];
for(var i=0; i<20; ++i) {
polylinePoints.push(hermiteSpline.evaluate(i/20));
}

var polylineCollection = new Cesium.PolylineCollection();