I'm trying to create a custom transition, to serve as a replacement for a default transition you would get here, for example:

[self.navigationController pushViewController:someController animated:YES];

I have prepared an OpenGL-based view that performs an effect on some static texture mapped to a plane (let's say it's a copy of the flip effect in Core Animation). What I don't know how to do is:

• grab current view content and make a texture out of it (I remember seeing a function that does just that, but can't find it)
• how to do the same for the view that is currently offscreen and is going to replace current view
• are there some APIs I can hook to in order to make my transition class as native as possible (make it a kind of Core Animation effect)?

Any thoughts or links are greatly appreciated!

UPDATE

Jeffrey Forbes's answer works great as a solution to capture the content of a view.

What I haven't figured out yet is how to capture the content of the view I want to transition to, which should be invisible until the transition is done.

Also, which method should I use to present the OpenGL view? For demonstration purposes I used pushViewController. That affects the navbar, though, which I actually want to go one item back, with animation, check this vid for explanation:

http://vimeo.com/4649397.

Another option would be to go with presentViewController, but that shows fullscreen. Do you think maybe creating another window (or view?) could be useful?