title: Graph not displayed while plotting 3D graph using vis.js
body: <p>I have started using vis.js javascript library. I came some problem while plotting using the following code:</p>
  
  <pre><code>var mydataset = new vis.DataSet();
  var counter =0;
  var steps = 50;  // number of datapoints will be steps*steps
  var thetaStep = 180/steps;
  var phiStep = 360/steps;
  for (var mytheta = -90; mytheta &lt;= 90; mytheta+=thetaStep)
  {
      for (var myphi = 0; myphi&lt;=360; myphi+=phiStep) 
      {
          var xcord = (Math.asin(Math.sin(mytheta*(Math.PI/180))*Math.cos(myphi*(Math.PI/180))))*(180/Math.PI);
          var ycord = (Math.asin(Math.sin(mytheta*(Math.PI/180))*Math.sin(myphi*(Math.PI/180))))*(180/Math.PI);
          var fvalue = Some_random_function(mytheta,myphi);
          var zcord = 20*Math.log10(fvalue);
          var style = zcord;
          mydataset.add({id:counter++,x:xcord,y:ycord,z:zcord,style:style}); 
      }
  }
  
  var options = {
      width:  '1200px',
      height: '1000px',
      style: 'surface',
      showPerspective: true,
      showGrid: true,
      showShadow: false,
      keepAspectRatio: true,
      verticalRatio: 0.5,
      tooltip:function(point){
          return 'value: &lt;b&gt;'+point.z+'&lt;/b&gt;';
      }
  };
  
  var container = document.getElementById('graph');
  var graph3d = new vis.Graph3d(container, mydataset, options);
  </code></pre>
  
  <p>I get no graph/chart displayed. But when I hover the mouse on the canvas region I get the tooltip indication as normally. Where did I go wrong.. No Graph but still tool tip is displayed. Need to change any options..??</p>
  
  <p>But when I plotted the graph using the below following code (by changing the xcord and ycord assignments)</p>
  
  <pre><code>var xcord = mytheta; //line #10
  var ycord = myphi; //line #11
  </code></pre>
  
  <p>There is some graph and nice tooltip indication. </p>
  
  <p>Is there anywhere I am going wrong.. Please help.. Thanks in advance</p>
  
  <p>Is there anyother javascript library where I can plot Nice Interactive ( panning and zooming ) 3D graphs.</p>