Suppose I use glReadPixels() to read the depth of a pixel from the depth buffer. What are the units of this? Is it the distance from the camera? Or the distance from the near clip plane? And is the distance normalized to clip space, or in real units?

• Oh, so its not just (depth - near_plane) / (far_plane - near_plane)? – Karnivaurus Jul 29 '15 at 17:30