In effect, a point rotated around its normal vector will not change the way it reflects light.

Any hyperplane of a Euclidean space has exactly two unit normal vectors.

The normal vectors are the rays the light is traveling down in ray optics.

Since the normal vector is, by definition, a length of one, only the angles need to be recorded.

One can recognize the vector in the second line above as the normal vector to the surface.

This means that at some junction between two pieces will have normal vectors pointing in opposite directions.

Now we look at light rays that are directed outward, along these normal vectors.

A vertex is a position along with other information such as color, normal vector and texture coordinates.

First, the normal vector for each plane is computed using some orthogonalization technique.

More specifically, the angle between the normal vectors can be computed.