title: How to use environment map in ARKit?
body: <p>ARKit 2.0 added a new class named AREnvironmentProbeAnchor. Reading it's instructions, it seems that ARKit can automatically collect environment texture (cubemap?). I believe that we can now create some virtual objects reflecting the real environment.</p>
  
  <p>But I am still not clear how this work, particularly how the environment texture is generated. Does anyone have simple sample code demonstrating this cool feature?</p>