Editing Shading (section)

=====Phong shading=====
Phong shading is similar to Gouraud shading, except that instead of interpolating the light intensities the normals are interpolated between the vertices and the lighting is evaluated per-pixel. Thus, the specular highlights are computed much more precisely than in the Gouraud shading model.

# Compute a normal N for each vertex of the polygon.
# Using [[bilinear interpolation]] compute a normal, N<sub>i</sub> for each pixel. (Normal has to be renormalized each time.)
# Apply an [[illumination model]] to each pixel to calculate the light intensity from N<sub>i</sub>.