title: Can't render video texture on iOS app using Kudan AR Unity plugin w/ Cardboard SDK
body: <p>I'm trying to replace my own SLAM code with Kudan Unity Plugin (1.2.1, native 1.2).
  I've already succeeded in building and running sample app on my iPhone.
  I also checked the plugin works on my Unity project on the editor.
  But when I build it on my iPhone, it does not render the video background as like in the <a href="http://i.stack.imgur.com/qH0Eq.jpg" rel="nofollow">picture</a>.</p>
  
  <p>I attached:</p>
  
  <ul>
  <li>KudanTracker to a camera, </li>
  </ul>
  
  <p>added:</p>
  
  <ul>
  <li>MarkerlessTransformDriver,  </li>
  <li>MarkerlessTracking,  </li>
  <li>and BackgroundRender
  as like in the sample.</li>
  </ul>
  
  <p>I appreciate if someone give me some suggestions for what I'm missing.
  Thank you in advance.</p>
  
  <p>UPDATE (7/13):</p>
  
  <p>I found that KudanSample scene also have same problem when Google Cardboard SDK plugin is added as shown in the <a href="http://i.stack.imgur.com/QVMcL.jpg" rel="nofollow">screenshot</a>.
  In this case, I just imported Cardboard plugin and didn't add any prefabs in it to the scene hierarchy. It seems some plugin parts of Kudan and Cardboard are conflicting.</p>
  
  <p>For trial, I deleted Cardboard's static library, libvrunity.a (and CardboardAppController.mm/h and entire "Cardboard" folder as they are referencing the library).
  As the result, Kudan could render video background.</p>
  
  <p>I also try to use the latest Google VR instead of Cardboard SDK, but the result was totally same as in the case of Cardboard.</p>
  
  <p>I'd appreciate if someone knows how to fix it. Any suggestions are very welcome.</p>
  
  <p>UPDATE (7/14):</p>
  
  <p>As the signing problem of Xcode is now fixed, I'm checking the debug log.
  It says "[KudanAR] Failed to create external textures".
  It indicates _textureYp or _textureCbCr is null in TrackeriOS.cs.
  _textureYpID and _textureCbCrId do not change whether I remove libvrunity.a or not.
  Therefore, maybe there are something wrong with GetTextureForPlane().
  I will keep you updated.</p>
  
  <p>UPDATE (7/15):</p>
  
  <p>I found that _textureYp and _textureCbCr are both null in TrackeriOS.
  As they are results of GetTextureForPlane(), I hope it can be solved by changing parameters for the function. Since I could't find the documents for the function, I would be very happy if someone give me the information about it.</p>