Polygon.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;


namespace PolygonIntersection {

	public class Polygon {

		private readonly List<Vector> points = new List<Vector>();
		private readonly List<Vector> edges = new List<Vector>();

		public void BuildEdges() {
			Vector p1;
			Vector p2;
			edges.Clear();
			for (int i = 0; i < points.Count; i++) {
				p1 = points[i];
				if (i + 1 >= points.Count) {
					p2 = points[0];
				} else {
					p2 = points[i + 1];
				}
				edges.Add(p2 - p1);
			}
		}

		public List<Vector> Edges {
			get { return edges; }
		}

		public List<Vector> Points {
			get { return points; }
		}

		public Vector Center {
			get {
				float totalX = 0;
				float totalY = 0;
				for (int i = 0; i < points.Count; i++) {
					totalX += points[i].X;
					totalY += points[i].Y;
				}

				return new Vector(totalX / (float)points.Count, totalY / (float)points.Count);
			}
		}

		public void Offset(Vector v) {
			Offset(v.X, v.Y);
		}

		public void Offset(float x, float y) {
			for (int i = 0; i < points.Count; i++) {
				Vector p = points[i];
				points[i] = new Vector(p.X + x, p.Y + y);
			}
		}

		public override string ToString() {
			string result = "";

			for (int i = 0; i < points.Count; i++) {
				if (result != "") result += " ";
				result += "{" + points[i].ToString(true) + "}";
			}

			return result;
		}

	}

}