Dorian - I have a small confusion some things and I just wanted to make sure I got it. First, why do needs to know about "diffuse reflection" in relation to shading? Isn't what makes the form 3d is where the light hits (reaches) its surface? 1. When you showed specular reflection, you used a mirror or chrome. Does it mean that all the lights gets the same value on every point of the ball because of the surface material? Does specular depends on the material or surface angle? 2. About the highlight. Why do we see highlight on rough surfaces (not chrome like) like body? I understood that it relates to specular reflection.