Realistic Topdown Camera

This is what I need help with:

<img src="http://i43.tinypic.com/2v9sls4.png" border="0" />

I want it so that if the camera Line of Sight hits the wall, it won't be seen. So if you are behind the corner (as in the picture) you won't be seen unless you step in the pink part.

My question is:

Are there any tutorials for this?

Sorry for some weird english.

There is a new behavior since r134 that does that for you : line of sight. There is also an example doing exactly what you describe in the example folder. Its name ? "line of sight" !

Enjoy :)

Guizmus is right; use the line of sight behavior to then order when/where the light should be shown.

I will try it out.

Thanks!