I'm trying to figure out how the cracked and chipped glass effect in a Bioshock Infinite Burial at Sea Episode 2 works.
My current guess is that it is essentially a transparent shader with gloss. It would have a map defining the direction of reflections from the environment, with the cracks being significantly different from the mesh's normals. It would also include some kind of model of the angular dependence of the amount of refraction/transmission to reflection so that it can roughly approximate Fesnel's equations.
It doesn't appear to be a full refractive model, so I'm wondering how exactly this is implemented? Am I right with what I have said above?