Beispiel #1
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);
            }
        }
Beispiel #2
0
        /// <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);
        }