For example this is what this angle should kind of look like
The blue area will be culled/transparented away, while only the small area in the be visible according to the characters sight line, and same with the area on the right
EDIT: ofcourse when you turn the camera to the right, the blue area will become solid and the wall on the left next to the player with the ladder will become culled, but the black parts will still remain until you move ofcourse