Using normal maps

Normal mapping is a technique for "faking" variations in a surface that doesn't really exist in the geometry of the surface. It is useful for producing surfaces that have bumps, dents, roughness, or wrinkles without actually providing enough position information (vertices) to fully define those deformations. The underlying surface is actually smooth, but is made to appear rough by varying the normal vectors using a texture (the normal map). The technique is closely related to bump mapping where the geometry of the surface is actually deformed based on a texture. With normal maps, instead of actually deforming the position, we modify the normal vectors. This creates the appearance of a bumpy surface without actually providing the geometry of the bumps.

A normal map is a texture in which the data stored within the texture is interpreted as normal vectors instead of colors. The normal vectors are typically encoded into the RGB information of the normal map such that the red...