I am trying to encode depth information as well as color, normal and other nifty things.
The problem is that on ATI, whenever I read from glFragCoord.z, the driver switches to software mode.
Short of throwing my card from the window and running the to store to make nVidia a little richer, is there another way?
It might be worth making sure point and line widths are set to 1 when trying to get the fragment position. I had a similar problem that was caused by this.