OpenGL/D3D: How do I get a screen grab of a game running full screen in Windows?

Question

Suppose I have an OpenGL game running full screen (Left 4 Dead 2). I\'d like to programmatically get a screen grab of it and then write it to a video file.

I\'ve tr

Answer 1

I've written screen grabbers in the past (DirectX7-9 era). I found good old DirectDraw worked remarkably well and would reliably grab bits of hardware-accelerated/video screen content which other methods (D3D, GDI, OpenGL) seemed to leave blank or scrambled. It was very fast too.