Vis Viva

You say photons are being absorbed and reemitted. Does'nt this affect their general direction? That can't be inside plain glass for example...

Ok, the way I get it is this: One can work out Maxwell's equations in conductive or nonconductive media, and find a slower characteristic wave speed for electromagnetic waves, than the value for this speed in vacuum. I'm having trouble however to see past these equations; how does this work on a subatomic scale? What does this picture look like? Is there constant absorbtion/reemission going on, slowing down the passage of the photon, or does the photon interfere somehow with the electrons wizzing around in the medium, or...? Any advise is welcome. (First time poster, please be gentle )