text: function initialize() {
      var urn =  'urn:' + Autodesk.Viewing.Private.getParameterByName('urn');
      var options = {
          'document' : urn,
          'env':'AutodeskProduction',
          'getAccessToken': getToken,
          'refreshToken': getToken,
      };
      var viewerElement = document.getElementById('viewer');
      var viewer = new Autodesk.Viewing.Private.GuiViewer3D(viewerElement,
          {
              extensions: ['Autodesk.ADN.Viewing.Extension.ModelStructure'],
              apiUrl: 'tt/extensions',
              extensionsUrl: 'extensions',
              extensionsSourceUrl: 'extensions',
              model : 'urn:dXJuOmFkc2sub2JqZWN0czpvcy5vYmplY3Q6cmVkYnVja2V0L2N5bGluZGVyLmYzZA=='
          });
      Autodesk.Viewing.Initializer(
          options,
          function() {
              viewer.start();
              loadDocument(viewer, options.document);
          }
      );
  }
  
  function getToken() {
      var accessToken;
  
      $.ajax({
          type: "GET",
          url: "../../tt/auth",
          async: false,
          success : function(data) {
              accessToken = data.access_token;
          }
      });
  
      return accessToken;
  }
  
  function loadDocument(viewer, documentId) {
      Autodesk.Viewing.Document.load(
          documentId,
          function(doc) {
              var geometryItems = [];
              geometryItems = Autodesk.Viewing.Document.getSubItemsWithProperties(doc.getRootItem(), {
                  'type' : 'geometry',
                  'role' : '3d'
              }, true);
              if (geometryItems.length > 0) {
                  viewer.load(doc.getViewablePath(geometryItems[0]));
              }
          },
          function(errorMsg) {
              alert("Load Error: " + errorMsg);
          }
      );
  }
  
  $(document).ready(function() {
      initialize();
      console.log("css");
  })