The window shows the mathematics used to compute the color of point 6 for a smooth shaded triangle. The computation uses weigthed averages and is sometimes called Gouraud interpolation. Since the color of point 6 is based on the colors of points 4 and 5, you can also view the computation of their colors. You make your choice of which computation is shown by clicking on a radio button in the selection panel. There are no interactive controls associated with this window.