Is there a way to Partially Obscure Objects?

Layers, my Lemony son. Layers are the key.

Going off the assumption that you don't know what layers are, press Ctrl+K to bring up the Layers toolbar (why MMF2 hides it by default so people don't tend to know about it is beyond me) and then press the plus sign to add a new layer. the highest numbered layer is at the front.

Layers are a liiiiiittle hard to explain really, but it's like having multiple clear sheets of plastic placed on top of each other. You can still see through each one, but if you put something on one layer, it will obscure anything on any layer below it. Using layers, you can keep your object in the front of the order, but still have some objects over top of it.

BONUS TIP: Layers are also really useful for HUDs and the like, if you put all of your HUD elements on the higher layer and set the scrolling coefficient (in the Properties window when you click on the layer) to 0, it will follow the screen around so you'll have a perfectly functional HUD that follows you around.

Working off the opposite assumption that you DO know what layers are, I must not understand what you're saying. In that case, I am of little help, and I'm sorry that I could not be.

Hope this helps!
Ethan

I don't think that's what he's asking.
I believe he's looking for something like the "intersect" option here:

Please login to see this picture.

And no, it's not really possible (in some very simple cases, it could be done with pixel shaders).

So something like in Portal 2 or whatever where if you can't see a portal, it outlines it for you? Or just like a hole in the wall? Because by all rights, a hole in the wall should be possible.

Still not sure I'm getting what he's saying.