Surface Finishes

### 3.8.1 Surface Finishes

One of the main features of a ray-tracer is its ability to do interesting things with surface finishes such as highlights and reflection. Let's add a nice little Phong highlight (shiny spot) to a sphere. To do this we need to add a `finish` keyword followed by a parameter. We change the definition of the sphere to this:

      sphere {
        <0, 1, 2>, 2
        texture {
          pigment { color Yellow } //Yellow is pre-defined in COLORS.INC
          finish { phong 1 }
        }
      }

We render the scene. The `phong` keyword adds a highlight the same color of the light shining on the object. It adds a lot of credibility to the picture and makes the object look smooth and shiny. Lower values of phong will make the highlight less bright (values should be between 0 and 1).