iPhone OpenGL : Adding a background image

Right so I got all my lovely openGL stuff working and I can开发者_如何学Go change the background colour via the property of the view or even the window however for the love of god I cant change it to an image.

• I have tried adding it to the nib
• I have tried adding a UIImageView as a subview.
• I have tried addiing it as a UIColor with Pattern
• I tried making the OpenGL view have a clear background and setting the

  image on the actual window.

Still no joy!

Issue a glClear then render 2 triangles (ie a quad) to the screen with the appropriate image texture mapped onto them.