polygon is a set of PHP classes that can be used to perform different types of geometric operations with arbitary polygons. It provides generic polygon and vertex classes that support mixing lines and arc segments between vertices. Polygons may be self-intersecting, convex, or concave. It provides means to perform intersection and union operations with the shapes and to compute shape clipping.
A plane figure having many angles, and consequently many sides; esp., one whose perimeter consists of more than four sides; any figure having many angles.
Polygons are two-dimensional shapes with any number of corners. Polygons are used for display in VRML, amongst other things.