예제 #1
0
        private static void FlipEdgeEvent(DTSweepContext tcx, PolygonPoint ep, PolygonPoint eq,
                                          DelaunayTriangle t, PolygonPoint p)
        {
            DelaunayTriangle ot = t.NeighborAcrossFrom(p);
            PolygonPoint     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");
            }

            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)
                    {
                        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
                {
                    Orientation o = TriangulationUtil.Orient2D(eq, op, ep);
                    t = NextFlipTriangle(tcx, o, t, ot, p, op);
                    FlipEdgeEvent(tcx, ep, eq, t, p);
                }
            }
            else
            {
                PolygonPoint newP = NextFlipPoint(ep, eq, ot, op);
                FlipScanEdgeEvent(tcx, ep, eq, t, ot, newP);
                EdgeEvent(tcx, ep, eq, t, p);
            }
        }
예제 #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, PolygonPoint ep, PolygonPoint eq,
                                              DelaunayTriangle flipTriangle, DelaunayTriangle t, PolygonPoint p)
        {
            DelaunayTriangle ot;
            PolygonPoint     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");
            }

            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);
            }
        }