I was reading this article: http://developer.download.nvidia.com/presentations/2007/D3DTutorial_Crytek.pdf on page 12 it mentions extracting world space position from a full screen quad.

Quote: For full screen effects have the distance from the camera's position to its four corner points at the far clipping plane interpolated Scale the pixel's normalized linear eye space depth by the interpolated distance and add the camera position (one mad instruction)

I wasn't quite sure what this meant, using varying vertex components etc. I thought I got it but now looking back over it I'm a bit hazy. could someone explain in terms of vertex/fragment shaders? [Edited by - LessBread on July 26, 2008 6:10:59 PM]

There's a good amount of discussion on this topic here in this thread. If you need anything explained further or cleared up, go ahead and ask.