Read off-screen pixles

OpenGL OpenGL: Advanced Coding
1

I have a window shows about a 7th of my world. I would like to render to a texture a small area of my world that may or may not be visible on screen. I believe glReadPixels() will only capture what appears on-screen.

Please could someone either point me towards a related post, or shed some light on how I might solve this.

Cheers
C

2

http://www.gamedev.net/reference/articles/article2331.asp

3

Look likes just what I need.

Thanks for the link.