How to activate entities by looking at an area

[FlawlessHappiness]

It works like this:
When the cursor is inside the area, the function is calling.

Ex. if the function is "LookAtAreaFunc"

then it is:

void LookAtAreaFunc(string &in asEntity, int alState)
{
if(alState == 1) //Only if the player is look at the area
{
//Do stuff
}
}