With separate cameras for UI & 3D scene sections
 - Double-tap to toggle between 3D models (teapot & cube)
 - Pan up/down on left side of screen to change roughness
 - Pan up/down on right side of screen to change metalness
 - Pan anywhere else to rotate scene

Change-Id: I51ec8436700c4e970221184d6875e4e9c501fafb