1 way transparent, light blocking wall

[ravo]

Hello, does anyone know how I can make a transparant wall(preferably 1 way) block light.
I want a dark room that allows you to look into a bright room but not the other way around.

Pls if you know how, or if you have seen this somewhere let me know. Ty

[Ace]

To make anything invisible, just add the surface flags "sky" and "nodraw".

You'll see in the map attached that I leave a 1x1 unit hole in the wall. The wall WILL NOT WORK correctly if there isnt a gap. You won't notice the hole anyways.

[ravo]

Thanks, I had tried sky but didnt know about a little hole for it to render thing.