title: Illuminate a rotating sphere from a specific point in xcode
body: <p>I've started working on an app and the basic idea is to to display a sphere which the user can rotate. I had no problems importing the .dae file of my sphere.
  When I add a lighting of any sort(omni, area, directional etc.) in the scene graph, after running my app, the light only illuminates one specific part of the sphere and rotates with the sphere. 
  I want to be able to rotate my sphere and have the light stay at a specific place such that I have a similar effect to the sun and earth. Only the area which is showing towards the sun/light should be illuminated when the sphere is rotating.</p>
  
  <p><a href="https://i.stack.imgur.com/835Pd.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/835Pd.jpg" alt="enter image description here"></a></p>
  
  <pre><code>let scene = SCNScene(named: "art.scnassets/untitled")!
  
      let cameraNode = SCNNode()
      cameraNode.camera = SCNCamera()
      cameraNode.position = SCNVector3(x:0, y:0, z: 100)
      scene.rootNode.addChildNode(cameraNode)
  
      let sceneView = self.view as! SCNView
      sceneView.scene = scene
      sceneView.showsStatistics = true
      sceneView.backgroundColor = UIColor.white
      sceneView.allowsCameraControl = true
  </code></pre>