Would it be possible to use some kind of pixel level testing .. ?
.. could this potentially all be done through vector math?
You're new to the site (and welcome!) so you should learn how to post an effective question.
First thing would be to read about posting to the forums. Although that link is about the Beginner's forum, there's a lot of good stuff that will help you get better answers to your questions. E.g., take a look under Asking Questions, at the line that begins "Be as descriptive as you can.."
The reason I'm redirecting you to that page is because your post so far is: "I'm drawing a shape. What's the distance from here to there?" See the problem?
Please don't PM me with questions. Post them in the forums for everyone's benefit, and I can embarrass myself publicly.
You don't forget how to play when you grow old; you grow old when you forget how to play.