1.-I am making some low poly objects with normal maps in cycles. All of them are working correctly but when I plug a normal map in a object with a glass shader it becomes opaque with some reflections on the surface. Is there an additional step to make normal maps work with a glass shader?
2.-I discover something weird. The fact is that I am using a tangent space normal map(purple map), but if I change the setting in the normal node from tangent to object space(blue and yellow map) it seems to work fine.
I uploaded a zip folder with the blend file and the normal map here: https://copy.com/ADi3bvAGpR9o