title: I want to create a straight line arrow using polyline in the Cesium Viewer. I'm using Firefox 40.0
body: <p>I'm trying to display a polyline using the Cesium Entities collection. I'm also using the entity.id to query the polyline and subsequently modify its position. The code below is basic. The Line is not displayed, (not rendered on the map).</p>
  
  <p>......
  obj = JSON.parse(myMsg);</p>
  
  <pre><code>var cmd      = obj.NET[0].CMD;
  var eid      = obj.NET[0].ID;      // Entity ID
  var lat1     = obj.NET[0].LAT1     // Latitude1
  var lon1     = obj.NET[0].LON1;    // Longitude1
  var alt1     = obj.NET[0].ALT1     // Altitude1
  var lat2     = obj.NET[0].LAT2     // Latitude2
  var lon2     = obj.NET[0].LON2     // Longitude2
  var alt2     = obj.NET[0].ALT2     // Altitude2
  
  var descr    = obj.NET[0].DESC;    // Description
  
  var myArry = [lon1, lat1, lon2, lat2];
  var pos = Cesium.Cartesian3.fromDegreesArrayHeights(myArry);
  
  if (cmd === "NEW") {
      viewer.entities.add({
          id : eid,
          polyline : {
              positions : pos,
              width : 5,
              followSurface : false,
              material : Cesium.Color.BLUE,
              show : true
          },
          description : descr,
      }); 
  </code></pre>
  
  <p>Any and all help would be appreciated (I'm new to the Cesium and also Javascript)</p>