If the surface within the material tended to fall more than one compound and light reflection and external surfaces will affect West and tends to reflect light in the same plane with the internal surface.
If the surface of the material, with vertical and horizontal reed reflection of light and the surface is oriented vertically incident and reflected on the same plane with the inner surface.
If the surface material inside the fall than the reflection of light and the impact and the outside surface is the impact of landscape reflect light in the same plane with the surface inside.