Glass Cage

I was wondering how to break the glass in the glass cage object. The glass comes as one whole piece so ..yea
I was trying to make a pic of broken glass but then i dont know how to make, what size and everthing. Plus how to make pieces of broken glass.

[gabe]

An object's subparts cannot change their structural properties (as an example, a piece of glass cannot shatter if it is a single subpart). It looks like the sides of the glass are separate subparts so you can move each piece. Apart from that, there is no simple way of creating a cage with broken glass.