Diffuse light comes from a particular direction and is reflected in various directions after collision with the surface of the object. In this section, we model this behavior by using the Phong Reflection Model, which was developed by Bui Tuong Phong in 1973. This model proposed an illumination shading technique that uses a normal surface and the direction of incident light. When light strikes on an object's surface, some of its parts are reflected and the rest is partially absorbed. Therefore, we can calculate either the intensity of light absorbed or reflected, if one of the components is given.

When 100 percent light intensity falls on a plain surface and 50 percent of it is reflected, it's obvious that 50 percent of light intensity is being absorbed or lost in the surroundings. In 3D graphics, we are only concerned with the reflected light intensity because...