In order to look solid, a polygon must be “shaded” with color.

This happens when the polygon is rendered. There are several ways to shade a polygon. These have varying degrees of realism and cost. A polygon’s shading depends on its surface properties, the properties and location of the lights with which it is lit. The shading methods (types) available on PictureMaker are constant, flat, Gouraud, and Phong. The latter two are “smooth” shading types.