C# DelaunayTriangle.PointCW方法代码示例

        /// <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)
                {
                    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;
                    }

                    bool inside = TriangulationUtil.SmartIncircle(p, t.PointCCW(p), t.PointCW(p), op);

                    if (inside)
                    {
                        // 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
                        bool notLegalized = !Legalize(tcx, t);

                        if (notLegalized)
                        {
                            tcx.MapTriangleToNodes(t);
                        }
                        notLegalized = !Legalize(tcx, ot);
                        if (notLegalized)
                        {
                            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;
        }

 /// <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");
     }
 }

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

            bool 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
            {
                TriangulationPoint newP = NextFlipPoint(ep, eq, ot, op);
                FlipScanEdgeEvent(tcx, ep, eq, flipTriangle, ot, newP);
            }
        }

        private static void FlipEdgeEvent(DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle t, TriangulationPoint p)
        {
            DelaunayTriangle ot = t.NeighborAcross(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 (t.GetConstrainedEdgeAcross(p))
            {
                throw new Exception("Intersecting Constraints");
            }

            bool 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)
                    {
                        t.MarkConstrainedEdge(ep, eq);
                        ot.MarkConstrainedEdge(ep, eq);
                        Legalize(tcx, t);
                        Legalize(tcx, ot);
                    }
                    else
                    {
                        // XXX: I think one of the triangles should be legalized here?
                    }
                }
                else
                {
                    // 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);
            }
        }

        private static void EdgeEvent(DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle triangle, TriangulationPoint point)
        {
            if (IsEdgeSideOfTriangle(triangle, ep, eq))
                return;

            TriangulationPoint 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");
                }
                return;
            }

            TriangulationPoint 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");
                }
                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);
            }
        }

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

        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)
                        {
            #if NETFX_CORE
                            Debug.WriteLine("[FLIP] - constrained edge done");
            #else
                            Console.WriteLine("[FLIP] - constrained edge done"); // TODO: remove
            #endif
                        }
                        t.MarkConstrainedEdge(ep, eq);
                        ot.MarkConstrainedEdge(ep, eq);
                        Legalize(tcx, t);
                        Legalize(tcx, ot);
                    }
                    else
                    {
                        if (tcx.IsDebugEnabled)
            #if NETFX_CORE
                          Debug.WriteLine("[FLIP] - subedge done"); // TODO: remove
            #else
                         Console.WriteLine("[FLIP] - subedge done"); // TODO: remove
            #endif
                        // XXX: I think one of the triangles should be legalized here?
                    }
                }
                else
                {
                    if (tcx.IsDebugEnabled)
            #if NETFX_CORE
                        Debug.WriteLine("[FLIP] - flipping and continuing with triangle still crossing edge"); // TODO: remove
            #else
                         Console.WriteLine("[FLIP] - flipping and continuing with triangle still crossing edge"); // TODO: remove
            #endif
                            // 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);
            }
        }