CentralizedControl/Veldrid.Common/Poly2Tri/Triangulation/Delaunay/Sweep/DTSweepContext.cs

/* Poly2Tri
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 * http://code.google.com/p/poly2tri/
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namespace Veldrid.Common.Poly2Tri.Triangulation.Delaunay.Sweep
{
	/**
	 * 
	 * @author Thomas Åhlén, thahlen@gmail.com
	 *
	 */
	public class DTSweepContext : TriangulationContext {
		// Inital triangle factor, seed triangle will extend 30% of 
		// PointSet width to both left and right.
		private readonly float ALPHA = 0.3f;

		public AdvancingFront     Front;
		public TriangulationPoint Head { get; set; }
		public TriangulationPoint Tail { get; set; }

		public DTSweepBasin     Basin     = new DTSweepBasin();
		public DTSweepEdgeEvent EdgeEvent = new DTSweepEdgeEvent();

		private DTSweepPointComparator _comparator = new DTSweepPointComparator();

		public DTSweepContext() {
			Clear();
		}

		public override bool IsDebugEnabled { get {
			return base.IsDebugEnabled;
		} protected set {
			if (value && DebugContext == null) DebugContext = new DTSweepDebugContext(this);
			base.IsDebugEnabled = value;
		}}

		public void RemoveFromList( DelaunayTriangle triangle ) {
			Triangles.Remove(triangle);
			// TODO: remove all neighbor pointers to this triangle
			//        for( int i=0; i<3; i++ )
			//        {
			//            if( triangle.neighbors[i] != null )
			//            {
			//                triangle.neighbors[i].clearNeighbor( triangle );
			//            }
			//        }
			//        triangle.clearNeighbors();
		}

		public void MeshClean( DelaunayTriangle triangle ) {
			MeshCleanReq(triangle);
		}

		private void MeshCleanReq( DelaunayTriangle triangle ) {
			if (triangle != null && !triangle.IsInterior) {
				triangle.IsInterior = true;
				Triangulatable.AddTriangle(triangle);

				for (int i = 0; i < 3; i++)
				if (!triangle.EdgeIsConstrained[i])
				{
					MeshCleanReq(triangle.Neighbors[i]);
				}
			}
		}

		public override void Clear() {
			base.Clear();
			Triangles.Clear();
		}

		public void AddNode( AdvancingFrontNode node ) {
			//        Console.WriteLine( "add:" + node.key + ":" + System.identityHashCode(node.key));
			//        m_nodeTree.put( node.getKey(), node );
			Front.AddNode(node);
		}

		public void RemoveNode( AdvancingFrontNode node ) {
			//        Console.WriteLine( "remove:" + node.key + ":" + System.identityHashCode(node.key));
			//        m_nodeTree.delete( node.getKey() );
			Front.RemoveNode(node);
		}

		public AdvancingFrontNode LocateNode( TriangulationPoint point ) {
			return Front.LocateNode(point);
		}

		public void CreateAdvancingFront() {
			AdvancingFrontNode head, tail, middle;
			// Initial triangle
			DelaunayTriangle iTriangle = new DelaunayTriangle(Points[0], Tail, Head);
			Triangles.Add(iTriangle);

			head = new AdvancingFrontNode(iTriangle.Points[1]);
			head.Triangle = iTriangle;
			middle = new AdvancingFrontNode(iTriangle.Points[0]);
			middle.Triangle = iTriangle;
			tail = new AdvancingFrontNode(iTriangle.Points[2]);

			Front = new AdvancingFront(head, tail);
			Front.AddNode(middle);

			// TODO: I think it would be more intuitive if head is middles next and not previous
			//       so swap head and tail
			Front.Head.Next = middle;
			middle.Next = Front.Tail;
			middle.Prev = Front.Head;
			Front.Tail.Prev = middle;
		}





		/// <summary>
		/// Try to map a node to all sides of this triangle that don't have 
		/// a neighbor.
		/// </summary>
		public void MapTriangleToNodes( DelaunayTriangle t ) {
			for (int i = 0; i < 3; i++)
			if (t.Neighbors[i] == null)
			{
				AdvancingFrontNode n = Front.LocatePoint(t.PointCWFrom(t.Points[i]));
				if (n != null) n.Triangle = t;
			}
		}

		public override void PrepareTriangulation( Triangulatable t ) {
			base.PrepareTriangulation(t);

			double xmax, xmin;
			double ymax, ymin;

			xmax = xmin = Points[0].X;
			ymax = ymin = Points[0].Y;

			// Calculate bounds. Should be combined with the sorting
			foreach (TriangulationPoint p in Points) {
				if (p.X > xmax) xmax = p.X;
				if (p.X < xmin) xmin = p.X;
				if (p.Y > ymax) ymax = p.Y;
				if (p.Y < ymin) ymin = p.Y;
			}

			double deltaX = ALPHA * (xmax - xmin);
			double deltaY = ALPHA * (ymax - ymin);
			TriangulationPoint p1 = new TriangulationPoint(xmax + deltaX, ymin - deltaY);
			TriangulationPoint p2 = new TriangulationPoint(xmin - deltaX, ymin - deltaY);

			Head = p1;
			Tail = p2;

			//        long time = System.nanoTime();
			// Sort the points along y-axis
			Points.Sort(_comparator);
			//        logger.info( "Triangulation setup [{}ms]", ( System.nanoTime() - time ) / 1e6 );
		}


		public void FinalizeTriangulation() {
			Triangulatable.AddTriangles(Triangles);
			Triangles.Clear();
		}

		public override TriangulationConstraint NewConstraint( TriangulationPoint a, TriangulationPoint b ) {
			return new DTSweepConstraint(a, b);
		}

		public override TriangulationAlgorithm Algorithm { get { return TriangulationAlgorithm.DTSweep; }}
	}
}