Fade screen black, but draw single objects above.

Ok I need a way to fade the screen black but keep drawing objects above it. What I did so far, was simply drawing a black rect on the HUD. This worked fine, however, I have no option to draw any 3dimensional objects above it.
Text would be enough already, but since I’m using the Rift, text which is drawn on the Hud is not displayed correctly (it is rendered twice for the left and the right screen).

How would I do this?
Thanks in advance.