As we saw previously in our first part, a perfectly diffuse material will send incident light back uniformly in all directions. At the other side of the spectrum, a perfect mirror only sends light in the opposite direction of the incident ray.

Reality is not as black and white as that, real object surfaces are often complex and difficult to model simply. I will describe here two empirical models of "shiny" surfaces that are not pure mirror.

This is the second part of the our series of articles about ray tracing in C++. It follows the part called "First rays".