Restricting Z-Buffer

I’m working on a visualisation tool and would like to take a horizontal cross section of a 3D model. For our purposes, a good way to understand what I am trying to do is extract a floor plan of a house by placing a camera above it and limiting the Z-buffer to a very limited depth. The vertical position and depth of the Z-buffer would need to be updated in real time. I can’t find much in the way of documentation that will help me. I have looked into using shaders but it seems that is overkill for such a simple task. Can anyone give me a suggestion as to where I should be looking?

Hmm, sounds like you are looking for changing the frustum near plane.
It might not work as you expect, but you can always try. =)

Thanks kwando,
I’ll give that a crack and let you know how it goes!

Will that work though? You would just get hollow spaces where you are expecting to see walls surely?