Plot clipping ffmatlib

Hi again!

Sorry to be bugging you all again, but I’ve got another question, this time regarding ffmatlib.
I would like to generate (and save) a plot in Matlab using ffmatlib displaying my function using colours on a 3D domain, something like this:

(this is a screenshot out of medit of something different).
I have seen the demos example capacitor_3d in the download of ffmatlib, but as far as I understand this only plots the “outside view” of the 3D body and I would like to know the function values inside (since my function has zero boundary, not the above).
I’ve been looking in this forum as well as in Matlab Help, but I’m not sure which of the two could solve this problem.

Thanks in advance for any inputs and ideas!

Of course, the obvious thing to do is an xlim in Matlab, as I did in the blow picture, but the problem is that the figure seems to be hollow… Does ffSaveData only save the boundary values or did I choose the wrong way to plot this?