Add static lables that fade in/out at the edge of view

Hi guys
I'd like to add static labels to a panorama, that would fade in when coming into view, and fade out when about to go out of view.
For example I have a scene with a public park. In front of me is a bench, and behind me is a swing. I want to label both those items. Then when I turn to see the swing, naturally the bench would go out of view since its behind me, so I want it's label to fade out as I turn away from it. As the swing comes into view, it's label should fade in.
How can I achieve something like that?

No clues from anybody?

Just before it goes out of view
So if you rotate clockwise, then new things come in from the right - they should fade in. Then as the move over to the left (because you are still rotating clockwise), it should fade out again as it gets near the left edge of the screen.

So no it should not fade out when not in view (that would have no point since you cant see it anyway). It should fade out just before it goes out of view.

If you then change rotation direction, things should fade in from the left and fade out from the right.
So if you can imagine a safeframe like in HD frame terms, in the center of the image, labels and hotspots etc are visible, but as soon as it goes out of the safeframe, it should fade out

Makes better sense now?