This shading is just a working hypothesis, that is not
Even when the illumination equation is applied at each point of the faceted
nature of the polygonal nature is still apparent. The issue is the dicontinuity
of normals !
To overcome this limitation normals are introduced at each vertex.
Usually different than the polygon normal
Used only for shading (not backface culling or other geometric computations)
Better approximates the "real" surface
Assumes the polygons were a piecewise approximation of the real surface
Normals provide information about the tangent plane at each point (C1)
Usually the average of the tangent of the neighbour facets
- not always (real discontinuity or more straightforwards value (sphere for