Polygon Modeling
Polygons are made up of faces. A single polygon face is a flat surface made when three or more points called vertices are connected. The position of each vertex defines the shape and size of the face, usually a triangle. The line that connects one vertex to another is called an edge. Some polygonal faces have four vertices instead of three, creating a square face instead of a triangular one.
Polygonal faces are attached along their polygonal edges to make up a more complex surface that constitutes your model (as shown with the polygonal sphere in Figure 4.2). A camping tent is a perfect example. The intersections of the poles are the faces' vertices. The poles are the edges of the faces, and the cloth draped over the tent's frame is the resultant surface.
Polygon models are the simplest for a computer to render, so they are used for gaming applications, which need to render the models as the game is running. Gaming artists create models with a small number of polygons—called low-count poly models—that a PC or game console can render in real time. Higher-resolution polygon models are frequently used in television and film work. In fact, a number of science fiction TV shows use polygonal models almost exclusively for their special effects. Because even complex polygon models can be made of a single surface, they are useful for character animation work as well. Models in character animation bend and warp a good deal, so having a single surface
Figure 4.2 A polygonal sphere and its components that will not separate at the seams can be advantageous. You'll get hands-on practice with polygon modeling later in this chapter.
Figure 4.2 A polygonal sphere and its components
Vertex Edge
Face (with selection handle visible)
Vertex Edge
Face (with selection handle visible)
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