Exemplo n.º 1
0
        /// <summary>
        /// Triangulate simple polygon with holes
        /// </summary>
        public static void Triangulate( DTSweepContext tcx )
        {
            tcx.CreateAdvancingFront();

            Sweep(tcx);

            // TODO: remove temporary
            // Check if the sweep algorithm is legalize robust
            // By doing a legalize on all triangles and see if anything happens
            // we know if the sweep algorithm missed some legalizations
            //        Console.WriteLine("============================");
            //        foreach ( DelaunayTriangle t in tcx.Triangles )
            //        {
            //            if( Legalize( tcx, t ) )
            //            {
            //                tcx.getDebugContext().setPrimaryTriangle( t );
            //                Console.WriteLine("[FIX] Triangle needed legalization after sweep");
            //            }
            //        }

            // Finalize triangulation
            if (tcx.TriangulationMode == TriangulationMode.Polygon) {
                FinalizationPolygon(tcx);
            } else {
                FinalizationConvexHull(tcx);
            }

            tcx.Done();
        }
Exemplo n.º 2
0
        /// <summary>
        /// Scan part of the FlipScan algorithm<br>
        /// When a triangle pair isn't flippable we will scan for the next 
        /// point that is inside the flip triangle scan area. When found 
        /// we generate a new flipEdgeEvent
        /// </summary>
        /// <param name="tcx"></param>
        /// <param name="ep">last point on the edge we are traversing</param>
        /// <param name="eq">first point on the edge we are traversing</param>
        /// <param name="flipTriangle">the current triangle sharing the point eq with edge</param>
        /// <param name="t"></param>
        /// <param name="p"></param>
        private static void FlipScanEdgeEvent( DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle flipTriangle, DelaunayTriangle t, TriangulationPoint p )
        {
            DelaunayTriangle ot;
            TriangulationPoint op, newP;
            bool inScanArea;

            ot = t.NeighborAcrossFrom(p);
            op = ot.OppositePoint(t, p);

            if (ot == null) {
                // If we want to integrate the fillEdgeEvent do it here
                // With current implementation we should never get here
                throw new Exception("[BUG:FIXME] FLIP failed due to missing triangle");
            }

            if (tcx.IsDebugEnabled) {
                Console.WriteLine("[FLIP:SCAN] - scan next point"); // TODO: remove
                tcx.DTDebugContext.PrimaryTriangle = t;
                tcx.DTDebugContext.SecondaryTriangle = ot;
            }

            inScanArea = TriangulationUtil.InScanArea(eq, flipTriangle.PointCCWFrom(eq), flipTriangle.PointCWFrom(eq), op);
            if (inScanArea) {
                // flip with new edge op->eq
                FlipEdgeEvent(tcx, eq, op, ot, op);
                // TODO: Actually I just figured out that it should be possible to
                //       improve this by getting the next ot and op before the the above
                //       flip and continue the flipScanEdgeEvent here
                // set new ot and op here and loop back to inScanArea test
                // also need to set a new flipTriangle first
                // Turns out at first glance that this is somewhat complicated
                // so it will have to wait.
            } else {
                newP = NextFlipPoint(ep, eq, ot, op);
                FlipScanEdgeEvent(tcx, ep, eq, flipTriangle, ot, newP);
            }
        }
Exemplo n.º 3
0
        private static void FlipEdgeEvent( DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle t, TriangulationPoint p )
        {
            DelaunayTriangle ot = t.NeighborAcrossFrom(p);
            TriangulationPoint op = ot.OppositePoint(t, p);

            if (ot == null) {
                // If we want to integrate the fillEdgeEvent do it here
                // With current implementation we should never get here
                throw new InvalidOperationException("[BUG:FIXME] FLIP failed due to missing triangle");
            }

            if (tcx.IsDebugEnabled) {
                tcx.DTDebugContext.PrimaryTriangle   = t;
                tcx.DTDebugContext.SecondaryTriangle = ot;
            } // TODO: remove

            bool inScanArea = TriangulationUtil.InScanArea(p, t.PointCCWFrom(p), t.PointCWFrom(p), op);
            if (inScanArea) {
                // Lets rotate shared edge one vertex CW
                RotateTrianglePair(t, p, ot, op);
                tcx.MapTriangleToNodes(t);
                tcx.MapTriangleToNodes(ot);

                if (p == eq && op == ep) {
                    if (eq == tcx.EdgeEvent.ConstrainedEdge.Q
                        && ep == tcx.EdgeEvent.ConstrainedEdge.P) {
                        if (tcx.IsDebugEnabled) Console.WriteLine("[FLIP] - constrained edge done"); // TODO: remove
                        t.MarkConstrainedEdge(ep, eq);
                        ot.MarkConstrainedEdge(ep, eq);
                        Legalize(tcx, t);
                        Legalize(tcx, ot);
                    } else {
                        if (tcx.IsDebugEnabled) Console.WriteLine("[FLIP] - subedge done"); // TODO: remove
                        // XXX: I think one of the triangles should be legalized here?
                    }
                } else {
                    if (tcx.IsDebugEnabled) Console.WriteLine("[FLIP] - flipping and continuing with triangle still crossing edge"); // TODO: remove
                    Orientation o = TriangulationUtil.Orient2d(eq, op, ep);
                    t = NextFlipTriangle(tcx, o, t, ot, p, op);
                    FlipEdgeEvent(tcx, ep, eq, t, p);
                }
            } else {
                TriangulationPoint newP = NextFlipPoint(ep, eq, ot, op);
                FlipScanEdgeEvent(tcx, ep, eq, t, ot, newP);
                EdgeEvent(tcx, ep, eq, t, p);
            }
        }
Exemplo n.º 4
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        private static void FinalizationPolygon( DTSweepContext tcx )
        {
            // Get an Internal triangle to start with
            DelaunayTriangle t = tcx.Front.Head.Next.Triangle;
            TriangulationPoint p = tcx.Front.Head.Next.Point;
            while (!t.GetConstrainedEdgeCW(p)) t = t.NeighborCCWFrom(p);

            // Collect interior triangles constrained by edges
            tcx.MeshClean(t);
        }
Exemplo n.º 5
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        private static void EdgeEvent( DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle triangle, TriangulationPoint point )
        {
            TriangulationPoint p1, p2;

            if (tcx.IsDebugEnabled) tcx.DTDebugContext.PrimaryTriangle=triangle;

            if (IsEdgeSideOfTriangle(triangle, ep, eq)) return;

            p1 = triangle.PointCCWFrom(point);
            Orientation o1 = TriangulationUtil.Orient2d(eq, p1, ep);
            if (o1 == Orientation.Collinear) {
                // TODO: Split edge in two
                ////            splitEdge( ep, eq, p1 );
                //            edgeEvent( tcx, p1, eq, triangle, point );
                //            edgeEvent( tcx, ep, p1, triangle, p1 );
                //            return;
                throw new PointOnEdgeException("EdgeEvent - Point on constrained edge not supported yet",eq,p1,ep);
            }

            p2 = triangle.PointCWFrom(point);
            Orientation o2 = TriangulationUtil.Orient2d(eq, p2, ep);
            if (o2 == Orientation.Collinear) {
                // TODO: Split edge in two
                //            edgeEvent( tcx, p2, eq, triangle, point );
                //            edgeEvent( tcx, ep, p2, triangle, p2 );
                //            return;
                throw new PointOnEdgeException("EdgeEvent - Point on constrained edge not supported yet",eq,p2,ep);
            }

            if (o1 == o2) {
                // Need to decide if we are rotating CW or CCW to get to a triangle
                // that will cross edge
                if (o1 == Orientation.CW) {
                    triangle = triangle.NeighborCCWFrom(point);
                } else {
                    triangle = triangle.NeighborCWFrom(point);
                }
                EdgeEvent(tcx, ep, eq, triangle, point);
            } else {
                // This triangle crosses constraint so lets flippin start!
                FlipEdgeEvent(tcx, ep, eq, triangle, point);
            }
        }
Exemplo n.º 6
0
        /// <summary>
        /// Start sweeping the Y-sorted point set from bottom to top
        /// </summary>
        private static void Sweep( DTSweepContext tcx )
        {
            var points = tcx.Points;
            TriangulationPoint point;
            AdvancingFrontNode node;

            for (int i = 1; i < points.Count; i++) {
                point = points[i];

                node = PointEvent(tcx, point);

                if (point.HasEdges) foreach (DTSweepConstraint e in point.Edges) {
                    if (tcx.IsDebugEnabled) tcx.DTDebugContext.ActiveConstraint = e;
                    EdgeEvent(tcx, e, node);
                }
                tcx.Update(null);
            }
        }
Exemplo n.º 7
0
 /// <summary>
 /// After a flip we have two triangles and know that only one will still be
 /// intersecting the edge. So decide which to contiune with and legalize the other
 /// </summary>
 /// <param name="tcx"></param>
 /// <param name="o">should be the result of an TriangulationUtil.orient2d( eq, op, ep )</param>
 /// <param name="t">triangle 1</param>
 /// <param name="ot">triangle 2</param>
 /// <param name="p">a point shared by both triangles</param>
 /// <param name="op">another point shared by both triangles</param>
 /// <returns>returns the triangle still intersecting the edge</returns>
 private static DelaunayTriangle NextFlipTriangle( DTSweepContext tcx, Orientation o, DelaunayTriangle t, DelaunayTriangle ot, TriangulationPoint p, TriangulationPoint op )
 {
     int edgeIndex;
     if (o == Orientation.CCW) {
         // ot is not crossing edge after flip
         edgeIndex = ot.EdgeIndex(p, op);
         ot.EdgeIsDelaunay[edgeIndex] = true;
         Legalize(tcx, ot);
         ot.EdgeIsDelaunay.Clear();
         return t;
     }
     // t is not crossing edge after flip
     edgeIndex = t.EdgeIndex(p, op);
     t.EdgeIsDelaunay[edgeIndex] = true;
     Legalize(tcx, t);
     t.EdgeIsDelaunay.Clear();
     return ot;
 }
Exemplo n.º 8
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 private static void FillLeftConcaveEdgeEvent( DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node )
 {
     Fill(tcx, node.Prev);
     if (node.Prev.Point != edge.P) {
         // Next above or below edge?
         if (TriangulationUtil.Orient2d(edge.Q, node.Prev.Point, edge.P) == Orientation.CW) {
             // Below
             if (TriangulationUtil.Orient2d(node.Point, node.Prev.Point, node.Prev.Prev.Point) == Orientation.CW) {
                 // Next is concave
                 FillLeftConcaveEdgeEvent(tcx, edge, node);
             } else {
                 // Next is convex
             }
         }
     }
 }
Exemplo n.º 9
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        /// <summary>
        /// Recursive algorithm to fill a Basin with triangles
        /// </summary>
        private static void FillBasinReq( DTSweepContext tcx, AdvancingFrontNode node )
        {
            if (IsShallow(tcx, node)) return; // if shallow stop filling

            Fill(tcx, node);
            if (node.Prev == tcx.Basin.leftNode && node.Next == tcx.Basin.rightNode) {
                return;
            } else if (node.Prev == tcx.Basin.leftNode) {
                Orientation o = TriangulationUtil.Orient2d(node.Point, node.Next.Point, node.Next.Next.Point);
                if (o == Orientation.CW) return;
                node = node.Next;
            } else if (node.Next == tcx.Basin.rightNode) {
                Orientation o = TriangulationUtil.Orient2d(node.Point, node.Prev.Point, node.Prev.Prev.Point);
                if (o == Orientation.CCW) return;
                node = node.Prev;
            } else {
                // Continue with the neighbor node with lowest Y value
                if (node.Prev.Point.Y < node.Next.Point.Y) {
                    node = node.Prev;
                } else {
                    node = node.Next;
                }
            }
            FillBasinReq(tcx, node);
        }
Exemplo n.º 10
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 private static void FillEdgeEvent( DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node )
 {
     if (tcx.EdgeEvent.Right) {
         FillRightAboveEdgeEvent(tcx, edge, node);
     } else {
         FillLeftAboveEdgeEvent(tcx, edge, node);
     }
 }
Exemplo n.º 11
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        /// <summary>
        /// Fills a basin that has formed on the Advancing Front to the right
        /// of given node.<br>
        /// First we decide a left,bottom and right node that forms the 
        /// boundaries of the basin. Then we do a reqursive fill.
        /// </summary>
        /// <param name="tcx"></param>
        /// <param name="node">starting node, this or next node will be left node</param>
        private static void FillBasin( DTSweepContext tcx, AdvancingFrontNode node )
        {
            if (TriangulationUtil.Orient2d(node.Point, node.Next.Point, node.Next.Next.Point) == Orientation.CCW) {
                // tcx.basin.leftNode = node.next.next;
                tcx.Basin.leftNode = node;
            } else {
                tcx.Basin.leftNode = node.Next;
            }

            // Find the bottom and right node
            tcx.Basin.bottomNode = tcx.Basin.leftNode;
            while (tcx.Basin.bottomNode.HasNext && tcx.Basin.bottomNode.Point.Y >= tcx.Basin.bottomNode.Next.Point.Y) tcx.Basin.bottomNode = tcx.Basin.bottomNode.Next;

            if (tcx.Basin.bottomNode == tcx.Basin.leftNode) return; // No valid basin

            tcx.Basin.rightNode = tcx.Basin.bottomNode;
            while (tcx.Basin.rightNode.HasNext && tcx.Basin.rightNode.Point.Y < tcx.Basin.rightNode.Next.Point.Y) tcx.Basin.rightNode = tcx.Basin.rightNode.Next;

            if (tcx.Basin.rightNode == tcx.Basin.bottomNode) return; // No valid basins

            tcx.Basin.width = tcx.Basin.rightNode.Point.X - tcx.Basin.leftNode.Point.X;
            tcx.Basin.leftHighest = tcx.Basin.leftNode.Point.Y > tcx.Basin.rightNode.Point.Y;

            FillBasinReq(tcx, tcx.Basin.bottomNode);
        }
Exemplo n.º 12
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        /// <summary>
        /// Fills holes in the Advancing Front
        /// </summary>
        private static void FillAdvancingFront( DTSweepContext tcx, AdvancingFrontNode n )
        {
            AdvancingFrontNode node;
            double angle;

            // Fill right holes
            node = n.Next;
            while (node.HasNext) {
                angle = HoleAngle(node);
                if (angle > PiDiv2 || angle < -PiDiv2) break;
                Fill(tcx, node);
                node = node.Next;
            }

            // Fill left holes
            node = n.Prev;
            while (node.HasPrev) {
                angle = HoleAngle(node);
                if (angle > PiDiv2 || angle < -PiDiv2) break;
                Fill(tcx, node);
                node = node.Prev;
            }

            // Fill right basins
            if (n.HasNext && n.Next.HasNext) {
                angle = BasinAngle(n);
                if (angle < PI_3div4) FillBasin(tcx, n);
            }
        }
Exemplo n.º 13
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        /// <summary>
        /// Adds a triangle to the advancing front to fill a hole.
        /// </summary>
        /// <param name="tcx"></param>
        /// <param name="node">middle node, that is the bottom of the hole</param>
        private static void Fill( DTSweepContext tcx, AdvancingFrontNode node )
        {
            DelaunayTriangle triangle = new DelaunayTriangle(node.Prev.Point, node.Point, node.Next.Point);
            // TODO: should copy the cEdge value from neighbor triangles
            //       for now cEdge values are copied during the legalize
            triangle.MarkNeighbor(node.Prev.Triangle);
            triangle.MarkNeighbor(node.Triangle);
            tcx.Triangles.Add(triangle);

            // Update the advancing front
            node.Prev.Next = node.Next;
            node.Next.Prev = node.Prev;
            tcx.RemoveNode(node);

            // If it was legalized the triangle has already been mapped
            if (!Legalize(tcx, triangle)) tcx.MapTriangleToNodes(triangle);
        }
Exemplo n.º 14
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        private static bool IsShallow( DTSweepContext tcx, AdvancingFrontNode node )
        {
            double height;

            if (tcx.Basin.leftHighest) {
                height = tcx.Basin.leftNode.Point.Y - node.Point.Y;
            } else {
                height = tcx.Basin.rightNode.Point.Y - node.Point.Y;
            }
            if (tcx.Basin.width > height) {
                return true;
            }
            return false;
        }
Exemplo n.º 15
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 private static void FillRightAboveEdgeEvent( DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node )
 {
     while (node.Next.Point.X < edge.P.X) {
         if (tcx.IsDebugEnabled) { tcx.DTDebugContext.ActiveNode = node; }
         // Check if next node is below the edge
         Orientation o1 = TriangulationUtil.Orient2d(edge.Q, node.Next.Point, edge.P);
         if (o1 == Orientation.CCW) {
             FillRightBelowEdgeEvent(tcx, edge, node);
         } else {
             node = node.Next;
         }
     }
 }
Exemplo n.º 16
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        /// <summary>
        /// Returns true if triangle was legalized
        /// </summary>
        private static bool Legalize( DTSweepContext tcx, DelaunayTriangle t )
        {
            // To legalize a triangle we start by finding if any of the three edges
            // violate the Delaunay condition
            for (int i = 0; i < 3; i++) {
                // TODO: fix so that cEdge is always valid when creating new triangles then we can check it here
                //       instead of below with ot
                if (t.EdgeIsDelaunay[i]) continue;

                DelaunayTriangle ot = t.Neighbors[i];
                if (ot == null) continue;

                TriangulationPoint p = t.Points[i];
                TriangulationPoint op = ot.OppositePoint(t, p);
                int oi = ot.IndexOf(op);
                // If this is a Constrained Edge or a Delaunay Edge(only during recursive legalization)
                // then we should not try to legalize
                if (ot.EdgeIsConstrained[oi] || ot.EdgeIsDelaunay[oi]) {
                    t.EdgeIsConstrained[i] = ot.EdgeIsConstrained[oi]; // XXX: have no good way of setting this property when creating new triangles so lets set it here
                    continue;
                }

                if (!TriangulationUtil.SmartIncircle(p,t.PointCCWFrom(p),t.PointCWFrom(p),op)) continue;

                // Lets mark this shared edge as Delaunay
                t.EdgeIsDelaunay[i] = true;
                ot.EdgeIsDelaunay[oi] = true;

                // Lets rotate shared edge one vertex CW to legalize it
                RotateTrianglePair(t, p, ot, op);

                // We now got one valid Delaunay Edge shared by two triangles
                // This gives us 4 new edges to check for Delaunay

                // Make sure that triangle to node mapping is done only one time for a specific triangle
                if (!Legalize(tcx, t)) tcx.MapTriangleToNodes(t);
                if (!Legalize(tcx, ot)) tcx.MapTriangleToNodes(ot);

                // Reset the Delaunay edges, since they only are valid Delaunay edges
                // until we add a new triangle or point.
                // XXX: need to think about this. Can these edges be tried after we
                //      return to previous recursive level?
                t.EdgeIsDelaunay[i] = false;
                ot.EdgeIsDelaunay[oi] = false;

                // If triangle have been legalized no need to check the other edges since
                // the recursive legalization will handles those so we can end here.
                return true;
            }
            return false;
        }
Exemplo n.º 17
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        private static void FillRightBelowEdgeEvent( DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node )
        {
            if (tcx.IsDebugEnabled) tcx.DTDebugContext.ActiveNode = node;

            if (node.Point.X < edge.P.X) { // needed?
                if (TriangulationUtil.Orient2d(node.Point, node.Next.Point, node.Next.Next.Point) == Orientation.CCW) {
                    // Concave
                    FillRightConcaveEdgeEvent(tcx, edge, node);
                } else {
                    // Convex
                    FillRightConvexEdgeEvent(tcx, edge, node);
                    // Retry this one
                    FillRightBelowEdgeEvent(tcx, edge, node);
                }

            }
        }
Exemplo n.º 18
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        /// <summary>
        /// Creates a new front triangle and legalize it
        /// </summary>
        private static AdvancingFrontNode NewFrontTriangle( DTSweepContext tcx, TriangulationPoint point, AdvancingFrontNode node )
        {
            AdvancingFrontNode newNode;
            DelaunayTriangle triangle;

            triangle = new DelaunayTriangle(point, node.Point, node.Next.Point);
            triangle.MarkNeighbor(node.Triangle);
            tcx.Triangles.Add(triangle);

            newNode = new AdvancingFrontNode(point) {Next = node.Next, Prev = node};
            node.Next.Prev = newNode;
            node.Next = newNode;

            tcx.AddNode(newNode); // XXX: BST

            if (tcx.IsDebugEnabled) tcx.DTDebugContext.ActiveNode = newNode;

            if (!Legalize(tcx, triangle)) tcx.MapTriangleToNodes(triangle);

            return newNode;
        }
Exemplo n.º 19
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 private static void FillRightConvexEdgeEvent( DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node )
 {
     // Next concave or convex?
     if (TriangulationUtil.Orient2d(node.Next.Point, node.Next.Next.Point, node.Next.Next.Next.Point) == Orientation.CCW) {
         // Concave
         FillRightConcaveEdgeEvent(tcx, edge, node.Next);
     } else {
         // Convex
         // Next above or below edge?
         if (TriangulationUtil.Orient2d(edge.Q, node.Next.Next.Point, edge.P) == Orientation.CCW) {
             // Below
             FillRightConvexEdgeEvent(tcx, edge, node.Next);
         } else {
             // Above
         }
     }
 }
Exemplo n.º 20
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        /// <summary>
        /// Find closes node to the left of the new point and
        /// create a new triangle. If needed new holes and basins
        /// will be filled to.
        /// </summary>
        private static AdvancingFrontNode PointEvent( DTSweepContext tcx, TriangulationPoint point )
        {
            AdvancingFrontNode node, newNode;

            node = tcx.LocateNode(point);
            if (tcx.IsDebugEnabled) tcx.DTDebugContext.ActiveNode = node;
            newNode = NewFrontTriangle(tcx, point, node);

            // Only need to check +epsilon since point never have smaller
            // x value than node due to how we fetch nodes from the front
            if (point.X <= node.Point.X + TriangulationUtil.Epsilon) Fill(tcx, node);

            tcx.AddNode(newNode);

            FillAdvancingFront(tcx, newNode);
            return newNode;
        }
Exemplo n.º 21
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        /// <summary>
        /// If this is a Delaunay Triangulation of a pointset we need to fill so the triangle mesh gets a ConvexHull 
        /// </summary>
        private static void FinalizationConvexHull( DTSweepContext tcx )
        {
            AdvancingFrontNode n1, n2, n3;
            DelaunayTriangle t1;
            TriangulationPoint first, p1;

            n1 = tcx.Front.Head.Next;
            n2 = n1.Next;
            n3 = n2.Next;
            first = n1.Point;

            TurnAdvancingFrontConvex(tcx, n1, n2);

            n1 = tcx.Front.Tail.Prev;
            if (n1.Triangle.Contains(n1.Next.Point) && n1.Triangle.Contains(n1.Prev.Point)) {
                t1 = n1.Triangle.NeighborAcrossFrom(n1.Point);
                RotateTrianglePair(n1.Triangle, n1.Point, t1, t1.OppositePoint(n1.Triangle, n1.Point));
                tcx.MapTriangleToNodes(n1.Triangle);
                tcx.MapTriangleToNodes(t1);
            }
            n1 = tcx.Front.Head.Next;
            if (n1.Triangle.Contains(n1.Prev.Point) && n1.Triangle.Contains(n1.Next.Point)) {
                t1 = n1.Triangle.NeighborAcrossFrom(n1.Point);
                RotateTrianglePair(n1.Triangle, n1.Point, t1, t1.OppositePoint(n1.Triangle, n1.Point));
                tcx.MapTriangleToNodes(n1.Triangle);
                tcx.MapTriangleToNodes(t1);
            }

            // TODO: implement ConvexHull for lower right and left boundary
            // Lower right boundary
            first = tcx.Front.Head.Point;
            n2 = tcx.Front.Tail.Prev;
            t1 = n2.Triangle;
            p1 = n2.Point;
            do {
                tcx.RemoveFromList(t1);
                p1 = t1.PointCCWFrom(p1);
                if (p1 == first) break;
                t1 = t1.NeighborCCWFrom(p1);
            } while (true);

            // Lower left boundary
            first = tcx.Front.Head.Next.Point;
            p1 = t1.PointCWFrom(tcx.Front.Head.Point);
            t1 = t1.NeighborCWFrom(tcx.Front.Head.Point);
            do {
                tcx.RemoveFromList(t1);
                p1 = t1.PointCCWFrom(p1);
                t1 = t1.NeighborCCWFrom(p1);
            } while (p1 != first);

            tcx.FinalizeTriangulation();
        }
Exemplo n.º 22
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        /// <summary>
        /// We will traverse the entire advancing front and fill it to form a convex hull.
        /// </summary>
        private static void TurnAdvancingFrontConvex( DTSweepContext tcx, AdvancingFrontNode b, AdvancingFrontNode c )
        {
            AdvancingFrontNode first = b;
            while (c != tcx.Front.Tail) {
                if (tcx.IsDebugEnabled) tcx.DTDebugContext.ActiveNode = c;

                if (TriangulationUtil.Orient2d(b.Point, c.Point, c.Next.Point) == Orientation.CCW) {
                    // [b,c,d] Concave - fill around c
                    Fill(tcx, c);
                    c = c.Next;
                } else {
                    // [b,c,d] Convex
                    if (b != first && TriangulationUtil.Orient2d(b.Prev.Point, b.Point, c.Point) == Orientation.CCW) {
                        // [a,b,c] Concave - fill around b
                        Fill(tcx, b);
                        b = b.Prev;
                    } else {
                        // [a,b,c] Convex - nothing to fill
                        b = c;
                        c = c.Next;
                    }
                }
            }
        }
Exemplo n.º 23
0
        private static void EdgeEvent( DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node )
        {
            try {
                tcx.EdgeEvent.ConstrainedEdge = edge;
                tcx.EdgeEvent.Right = edge.P.X > edge.Q.X;

                if (tcx.IsDebugEnabled) { tcx.DTDebugContext.PrimaryTriangle = node.Triangle; }

                if (IsEdgeSideOfTriangle(node.Triangle, edge.P, edge.Q)) return;

                // For now we will do all needed filling
                // TODO: integrate with flip process might give some better performance
                //       but for now this avoid the issue with cases that needs both flips and fills
                FillEdgeEvent(tcx, edge, node);

                EdgeEvent(tcx, edge.P, edge.Q, node.Triangle, edge.Q);
            } catch ( PointOnEdgeException e) {
                //Debug.WriteLine( String.Format( "Warning: Skipping Edge: {0}", e.Message ) );
                throw;
            }
        }