In the previous part, we’ve fixed a random color per face to be able to see the mesh. We’re now going to change that to compute the angle between a light and each face to have a better illumination. The first algorithm reviewed is named the Flat Shading. It’s using per face normals. We will still see the polygons using this approach. But thanks to Gouraud Shading, we will go one step further. This one uses per vertex normals. It will then interpolate the color per pixel using 3 normals.