Recognizing a logged in forum member

[astonishedman]

I have seen a few topics discussing this but no real concrete answers. What I am after is a little simpler than some of the other questions.

I have a feature or two that reside outside of the forum, but on the same domain and server. I simply want to recognize if the visitor on the page is logged into their forum account. I know vB doesn't use session variables and I've dug into the code a little to see how it is they recognize the member, but haven't had much luck.

Here is basically what I want to do in PHP:
if( condition to determine if they are logged in ){
present feature
}else{
display message requesting they login
}

I was hoping to not have to load the whole vB engine and such. Maybe include a file or two and check a variable.

What is the most straight forward approach to program this check? Necessary files? Variable to poll?

Thanks.

[ChristianAlfred]

I also need to know