Exemple #1
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        /// <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.NeighborAcross(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");
            }

            inScanArea = TriangulationUtil.InScanArea(eq, flipTriangle.PointCCW(eq), flipTriangle.PointCW(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);
            }
        }
 public abstract TriangulationConstraint NewConstraint(TriangulationPoint a, TriangulationPoint b);
Exemple #3
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 /// <summary>
 /// When we need to traverse from one triangle to the next we need 
 /// the point in current triangle that is the opposite point to the next
 /// triangle. 
 /// </summary>
 private static TriangulationPoint NextFlipPoint(TriangulationPoint ep, TriangulationPoint eq,
                                                 DelaunayTriangle ot, TriangulationPoint op)
 {
     Orientation o2d = TriangulationUtil.Orient2d(eq, op, ep);
     if (o2d == Orientation.CW)
     {
         // Right
         return ot.PointCCW(op);
     }
     else if (o2d == Orientation.CCW)
     {
         // Left
         return ot.PointCW(op);
     }
     else
     {
         // TODO: implement support for point on constraint edge
         throw new PointOnEdgeException("Point on constrained edge not supported yet");
     }
 }
Exemple #4
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 /// <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;
 }
Exemple #5
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        private static void EdgeEvent(DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq,
                                      DelaunayTriangle triangle, TriangulationPoint point)
        {
            TriangulationPoint p1, p2;

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

            p1 = triangle.PointCCW(point);
            Orientation o1 = TriangulationUtil.Orient2d(eq, p1, ep);
            if (o1 == Orientation.Collinear)
            {
                if (triangle.Contains(eq, p1))
                {
                    triangle.MarkConstrainedEdge(eq, p1);
                    // We are modifying the constraint maybe it would be better to 
                    // not change the given constraint and just keep a variable for the new constraint
                    tcx.EdgeEvent.ConstrainedEdge.Q = p1;
                    triangle = triangle.NeighborAcross(point);
                    EdgeEvent(tcx, ep, p1, triangle, p1);
                }
                else
                {
                    throw new PointOnEdgeException("EdgeEvent - Point on constrained edge not supported yet");
                }
                if (tcx.IsDebugEnabled)
                {
                    Debug.WriteLine("EdgeEvent - Point on constrained edge");
                }
                return;
            }

            p2 = triangle.PointCW(point);
            Orientation o2 = TriangulationUtil.Orient2d(eq, p2, ep);
            if (o2 == Orientation.Collinear)
            {
                if (triangle.Contains(eq, p2))
                {
                    triangle.MarkConstrainedEdge(eq, p2);
                    // We are modifying the constraint maybe it would be better to 
                    // not change the given constraint and just keep a variable for the new constraint
                    tcx.EdgeEvent.ConstrainedEdge.Q = p2;
                    triangle = triangle.NeighborAcross(point);
                    EdgeEvent(tcx, ep, p2, triangle, p2);
                }
                else
                {
                    throw new PointOnEdgeException("EdgeEvent - Point on constrained edge not supported yet");
                }
                if (tcx.IsDebugEnabled)
                {
                    Debug.WriteLine("EdgeEvent - Point on constrained edge");
                }
                return;
            }

            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.NeighborCCW(point);
                }
                else
                {
                    triangle = triangle.NeighborCW(point);
                }
                EdgeEvent(tcx, ep, eq, triangle, point);
            }
            else
            {
                // This triangle crosses constraint so lets flippin start!
                FlipEdgeEvent(tcx, ep, eq, triangle, point);
            }
        }
Exemple #6
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        private static void FlipEdgeEvent(DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq,
                                          DelaunayTriangle t, TriangulationPoint p)
        {
            TriangulationPoint op, newP;
            DelaunayTriangle ot;
            bool inScanArea;

            ot = t.NeighborAcross(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 InvalidOperationException("[BUG:FIXME] FLIP failed due to missing triangle");
            }

            inScanArea = TriangulationUtil.InScanArea(p, t.PointCCW(p), t.PointCW(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
            {
                newP = NextFlipPoint(ep, eq, ot, op);
                FlipScanEdgeEvent(tcx, ep, eq, t, ot, newP);
                EdgeEvent(tcx, ep, eq, t, p);
            }
        }
Exemple #7
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 //TODO: Port note: There were some structural differences here.
 private static bool IsEdgeSideOfTriangle(DelaunayTriangle triangle, TriangulationPoint ep, TriangulationPoint eq)
 {
     int index;
     index = triangle.EdgeIndex(ep, eq);
     if (index != -1)
     {
         triangle.MarkConstrainedEdge(index);
         triangle = triangle.Neighbors[index];
         if (triangle != null)
         {
             triangle.MarkConstrainedEdge(ep, eq);
         }
         return true;
     }
     return false;
 }
Exemple #8
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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);
            newNode.Next = node.Next;
            newNode.Prev = node;
            node.Next.Prev = newNode;
            node.Next = newNode;

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

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

            return newNode;
        }
Exemple #9
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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);
            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;
        }
Exemple #10
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        /// <summary>
        /// Rotates a triangle pair one vertex CW
        ///       n2                    n2
        ///  P +-----+             P +-----+
        ///    | t  /|               |\  t |  
        ///    |   / |               | \   |
        ///  n1|  /  |n3           n1|  \  |n3
        ///    | /   |    after CW   |   \ |
        ///    |/ oT |               | oT \|
        ///    +-----+ oP            +-----+
        ///       n4                    n4
        /// </summary>
        private static void RotateTrianglePair(DelaunayTriangle t, TriangulationPoint p, DelaunayTriangle ot,
                                               TriangulationPoint op)
        {
            DelaunayTriangle n1, n2, n3, n4;
            n1 = t.NeighborCCW(p);
            n2 = t.NeighborCW(p);
            n3 = ot.NeighborCCW(op);
            n4 = ot.NeighborCW(op);

            bool ce1, ce2, ce3, ce4;
            ce1 = t.GetConstrainedEdgeCCW(p);
            ce2 = t.GetConstrainedEdgeCW(p);
            ce3 = ot.GetConstrainedEdgeCCW(op);
            ce4 = ot.GetConstrainedEdgeCW(op);

            bool de1, de2, de3, de4;
            de1 = t.GetDelaunayEdgeCCW(p);
            de2 = t.GetDelaunayEdgeCW(p);
            de3 = ot.GetDelaunayEdgeCCW(op);
            de4 = ot.GetDelaunayEdgeCW(op);

            t.Legalize(p, op);
            ot.Legalize(op, p);

            // Remap dEdge
            ot.SetDelaunayEdgeCCW(p, de1);
            t.SetDelaunayEdgeCW(p, de2);
            t.SetDelaunayEdgeCCW(op, de3);
            ot.SetDelaunayEdgeCW(op, de4);

            // Remap cEdge
            ot.SetConstrainedEdgeCCW(p, ce1);
            t.SetConstrainedEdgeCW(p, ce2);
            t.SetConstrainedEdgeCCW(op, ce3);
            ot.SetConstrainedEdgeCW(op, ce4);

            // Remap neighbors
            // XXX: might optimize the markNeighbor by keeping track of
            //      what side should be assigned to what neighbor after the 
            //      rotation. Now mark neighbor does lots of testing to find 
            //      the right side.
            t.Neighbors.Clear();
            ot.Neighbors.Clear();
            if (n1 != null) ot.MarkNeighbor(n1);
            if (n2 != null) t.MarkNeighbor(n2);
            if (n3 != null) t.MarkNeighbor(n3);
            if (n4 != null) ot.MarkNeighbor(n4);
            t.MarkNeighbor(ot);
        }
Exemple #11
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 public abstract TriangulationConstraint NewConstraint(TriangulationPoint a, TriangulationPoint b);