This is one of the most creative aspects of 3-D graphics, both for the programmers developing the tools and for the artists using them. Think about it for a second. When an artist models in clay, he or she shapes the physical object in true 3-D space using his or her hands. Every 3-D application handles modeling differently. One of the most important factors in choosing an application is comfort with the modeling tools.
Some applications provide fabulous control in model building, at the cost of complexity.
Other applications are easier to use and more intuitive, but may not provide as much control. Yet, underlying all of the different implementations are some very basic concepts. We will review these concepts in the following two parts of this tutorial. Thus far, we have been describing a 3-D model as a mesh of polygons. Some applications, such as Lightwave 3D, model directly in polygons.