title: Detecting which side touched in openGLES 3dbox in iphone
body: <p>i am working on a project that contains a 3d box that rotated by user touch and opens revelant page when clicked on a side. each side has link to another view so i need to know which side is clicked on the program. </p>
  
  <p>i am using Brad Larson's wonderfull example in my app and i can rotate the cube with touch, thanx to his code and time. </p>
  
  <p>( the code is linked in here: <a href="https://stackoverflow.com/questions/2857463/where-to-start-opengl-es-to-create-and-rotate-a-cube-in-an-iphone">Where to start openGL ES to create and rotate a cube in an iPhone?</a> )</p>
  
  <p>now i need to know how to detect whick side is clicked on the box. normally i develop view based applications, i really have no idea on openGL or things like that. </p>
  
  <p>i've searched the site but couldnt find a good answer (at least something that i can understand with my opengl knowledge) </p>
  
  <p>P.S: Here, the 3dCube code from Brad Larson: <a href="http://www.sunsetlakesoftware.com/sites/default/files/CubeExample.zip" rel="nofollow noreferrer">http://www.sunsetlakesoftware.com/sites/default/files/CubeExample.zip</a></p>