There are several ways to create 2D polygons. Single-line polygons, double-line polygons, and regular polygons can be created; a polygon always has square vertices and is composed of a series of straight line segments. A polygon that represents a curve will require more vertices (and more complexity) than a polyline.
Polygons can be created automatically from existing geometry, which is especially useful for illustrating the elements of a hidden-line rendered viewport.
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