How to make a screenshot of OpenGl ES on top of the live preview camera in iOS (Augmented Reality app)?

I am a very beginner in Objective-C and iOS programming. I spent a month to find out how to show a 3D model using OpenGL ES (version 1.1) on top of the live camera preview by using AvFoundation. I am doing a kind of augmented reality application on iPad. I process the input frames and show 3D object overlay with the camera preview in realtime. These was fine because there are so many site and tutorial about these things (Thanks to this website as well).

Now, I want to make a screen capture of the whole screen (the model with camera preview as the background) as the image and show in the next screen. I found a really good demonstration here, http://cocoacoderblog.com/2011/03/30/screenshots-a-legal-way-to-get-screenshots/. He did everything I want to do. But, as I said before, I am so beginner and don't understand the whole project without explanation in details. So, I'm stuck for a while because I don't know how to implement this.

Does any开发者_运维百科body know any of good tutorial or any kind of source in this topic or any suggestion that I should learn more in order to do this screen capture? This will help me a lot to moving on.

Thank you in advance.

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I'm currently attempting to solve this same problem to allow a user to take a screenshot of an Augmented Reality app. (We use Qualcomm's AR SDK plugged into Unity 3D to make our AR apps, which saved me from ever having to learn how to programmatically render OpenGL models)

For my solution I am first looking at implementing the second answer found here: How to take a screenshot programmatically

Barring that I will have to re-engineer the "Combined Screenshots" method found in CocoaCoder's Screenshots app.

I'll check back in when I figure out which one works better.

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Here are 3 very helpful links to capture screenshot:

OpenGL ES View Snapshot

How to capture video frames from the camera as images using AV Foundation

How do I take a screenshot of my app that contains both UIKit and Camera elements

Enjoy