I have created a nice grungy glass material, using the technique from one of the tutorials on Blender Guru. The node set up is pretty much the same as the one in the tutorial.
I’d like to add a broken glass texture to it such as one of the following from CG Textures (or something similar). What I need to know is how to set it up, I’d like to do it in such a way that the hole in the glass does not show the grungy texture of the glass but allows the background to show through clearly.
If anyone can give me some pointers I’d be extremely grateful.