title: shadowRadius doesn't blur the shadow
body: <p>I'm trying to set a blurry shadow on my box. This is what I got so far.<img src="https://i.stack.imgur.com/OuboT.png" alt="enter image description here"> </p>
  
  <p>The documentation on shadowRadius says. </p>
  
  <blockquote>
    <p>SceneKit produces soft-edged shadows by rendering the silhouettes of
    geometry into a 2D shadow map and then using several weighted samples
    from the shadow map to determine the strength of the shadow at each
    pixel in the rendered scene. This property controls the radius of
    shadow map sampling. Lower numbers result in shadows with sharply
    defined, pixelated edges; higher numbers result in blurry shadows.</p>
  </blockquote>
  
  <p>this is my shadow setup code</p>
  
  <pre><code>func setupShadow(){
          spotLight.castsShadow = true
          spotLight.shadowRadius = 30000
          spotLight.shadowBias = 1
          spotLight.shadowColor = UIColor.blackColor()
      }
  </code></pre>
  
  <p>As you can see, the shadow radius is set to a huge number but the shadow remains edgy. In fact, blurriness does not even change if shadowRadius changes. What am I doing wrong?</p>