Question

Difference between smooth and flat shading

Answer 1

Answer:

flat shading gives a single colour to a whole whole face whereas smooth shading inter polates across a single face or many faces depending on lighting

Answer 2

Answer:

For smooth shading, two adjacent triangle must share common vertex normal. The reason is interpolation. The normal from one vertex is smoothly interpolated to the normal on the second vertex. You need the ensure that the normal of triangle at all adjacent triangle at particular vertex matches the normal of all adjacent triangle at that same vertex.

With a flat shading, the normal of each vertex on every triangle must be the same so that when interpolated the value is same across the whole surface. This means that if a single vertex is shared by multiple triangle then the vertex must be duplicated for each triangle in order to have an independent normal for each triangle.