Computational Geometry

1. Computer Graphics
1 of 1
Lesson 3: Introduction to Polygons
Author: Kasun Ranga Wijeweera
Email: krw19870829@gmail.com
Date: 2020 August 15
Definition of a Polygon
Let v0, v1, v2,…, vn – 1 be n points in the plane. The index arithmetic is
MODULO n, implying a cyclic ordering of the points. Let e0 = v0v1,
e1 = v1v2,…, en – 1 = vn – 1v0 be straight line segments connecting the
points. Then these straight line segments bound a polygon if and only
if
1) The intersection of each pair of straight line segments adjacent in
the cyclic ordering is the single point shared between them.
2) Nonadjacent straight line segments do not intersect.
The points vi are called the “vertices” of the polygon, and the
straight line segments ei are called its “edges”. Note that a polygon of
n vertices has n edges.
v0
v1
v2vn - 1
e0
e1
en - 1