Commands.cs

@@ -111,12 +111,7 @@ namespace Boprs
 			
 			BooleanOperation bopr = new BooleanOperation(subject, clip, type);
 
-			List <Contour> contours = bopr.Result.GetContourCopies();
-
-			foreach (Contour contour in contours)
-			{
-				contour.Draw();
-			}
+			bopr.Result.Draw();
 		}
 	}
 }

Contour.cs

@@ -20,17 +20,17 @@ namespace Boprs
 	/// <summary>
 	/// Simple closed polygon.
 	/// </summary>
-	public class Contour : ICloneable
+	public class Contour
 	{
-		public object Clone()
-		{
-			return new Contour() { Vertices = new List<Point2d>(Vertices) }; 
-		}
+		/// <summary>
+		/// Depth of the contour within the region.
+		/// </summary>
+		internal int ContourDepth { get; set; }
 
 		/// <summary>
 		/// Vertices of the contour.
 		/// </summary>
-		public List<Point2d> Vertices { get; private set; }
+		public List<Point2d> Vertices { get; }
 
 		/// <summary>
 		/// Are the vertices of the contour arranged in clockwise manner?
@@ -70,6 +70,7 @@ namespace Boprs
 		/// </summary>
 		public Contour()
 		{
+			ContourDepth = 0;
 			Vertices = new List<Point2d>();
 		}
 

Region.cs

@@ -151,33 +151,40 @@ namespace Boprs
 			// Lexico-graphically sort the vertices.
 			vertices.Sort();
 
+			// Sweepline to keep track of edges.
+			SweepLine sweepLine = new SweepLine();
+
 			bool[] processed = new bool[vertices.Count]; 
 			List<Contour> contours = new List<Contour>();
 
 			for(int i = 0; i < vertices.Count; i++)
 			{
-				// If we already traversed this vertex, skip it.
+				SweepVertex acVx = vertices[i];
+
+				if (acVx.IsLeft())
+				{
+					sweepLine.Add(acVx.Edge, false);
+				}
+				else
+				{ 
+					sweepLine.Remove(acVx.Edge);
+				}
+
 				if (processed[i])
 				{
 					continue;
 				}
 
-				// Otherwise this is an edge on an indiscovered contour, create it.
 				Contour contour = new Contour();
 				contours.Add(contour);
 
-				// acVx should be guaranteed to be the lowest and leftest vertex of the new polygon.
-				// Thus it cannot be vertical.
-				// if it is transition inside, it is a positive contour and should wind counter-clockwise,
-				// if it is transition outside, it is a negative contour and should wind clockwise.
-				SweepVertex acVx = vertices[i];
-				bool shouldBeCW = !acVx.Edge.TransitionInside;
+				SweepEdge prev = sweepLine.PrevEdge(acVx.Edge);
+				bool shouldBeCW = prev == null ? false : prev.TransitionInside;
+
+				Point2d target = acVx.Point;
 
-				// Traverse connected edges, and mark taversed vertices as processed,
-				// until we loop back to the first discovered vertex on the contour.
 				int pos = i;
 				processed[i] = true;
-				Point2d target = acVx.Point;
 				contour.Vertices.Add(vertices[pos].Point);
 				acVx.Edge.ParentContour = contour;
 				while (!Utils.DoubleEquals(vertices[pos].OtherVertex().Point.GetDistanceTo(target), 0))
@@ -193,7 +200,6 @@ namespace Boprs
 				}
 				processed[vertices.IndexOf(vertices[pos].OtherVertex())] = true;
 				
-				// If the contour is a hole and winds ccw, or positive and winds cw, flip it.
 				if (shouldBeCW != contour.IsClockwise())
 				{
 					contour.Reverse();
@@ -224,14 +230,7 @@ namespace Boprs
 		/// <returns>List of copies of the regions contours.</returns>
 		public List<Contour> GetContourCopies()
 		{
-			List<Contour> copies = new List<Contour>();
-
-			foreach (Contour contour in Contours)
-			{
-				copies.Add((Contour)contour.Clone());
-			}
-
-			return copies;
+			throw new NotImplementedException();
 		}
 
 		/// <summary>
@@ -258,5 +257,15 @@ namespace Boprs
 
 			return region;
 		}
+
+#if DEBUG
+		internal void Draw()
+		{
+			foreach (Contour contour in Contours)
+			{
+				contour.Draw();
+			}
+		}
+#endif
 	}
 }