/// <summary>
        /// True if it crosses the line. Provides the intersection points.
        /// </summary>
        /// <param name="Line">The other line.</param>
        /// <param name="IntersectionPts">Output. The intersection points.</param>
        public bool Crosses(C2DLineBase Line, List <C2DPoint> IntersectionPts)
        {
            var LineRect = new C2DRect();

            Line.GetBoundingRect(LineRect);

            if (!BoundingRect.Overlaps(LineRect))
            {
                return(false);
            }

            Debug.Assert(Lines.Count == LineRects.Count);

            if (Lines.Count != LineRects.Count)
            {
                return(false);
            }

            var IntersectionTemp = new C2DPointSet();

            var bResult = false;

            for (var i = 0; i < this.Lines.Count; i++)
            {
                if (LineRects[i].Overlaps(LineRect) &&
                    Lines[i].Crosses(Line, IntersectionTemp as List <C2DPoint>))
                {
                    bResult = true;
                }
            }

            IntersectionPts.InsertRange(0, IntersectionTemp);

            return(bResult);
        }
        /// <summary>
        /// True if it crosses the other.
        /// </summary>
        /// <param name="Other">The other polygon.</param>
        public bool Crosses(C2DPolyBase Other)
        {
            if (!BoundingRect.Overlaps(Other.BoundingRect))
            {
                return(false);
            }

            var Temp = new List <C2DPoint>();

            for (var i = 0; i < Lines.Count; i++)
            {
                if (Other.Crosses(Lines[i], Temp))
                {
                    return(true);
                }
            }
            return(false);
        }
        /// <summary>
        /// Intersection with another.
        /// </summary>
        /// <param name="Other">The other polygon.</param>
        /// <param name="IntersectionPts">Output. The intersection points.</param>
        public bool Crosses(C2DPolyBase Other, List <C2DPoint> IntersectionPts)
        {
            if (!BoundingRect.Overlaps(Other.BoundingRect))
            {
                return(false);
            }

            var IntPtsTemp = new List <C2DPoint>();
            var Index1     = new List <int>();
            var Index2     = new List <int>();

            Lines.GetIntersections(Other.Lines, IntPtsTemp, Index1, Index2,
                                   BoundingRect, Other.BoundingRect);

            var bResult = IntPtsTemp.Count > 0;

            IntersectionPts.InsertRange(0, IntPtsTemp);

            return(bResult);
        }
        /// <summary>
        /// Gets the boolean operation with the other. e.g. union / intersection.
        /// </summary>
        /// <param name="Other">The other polygon.</param>
        /// <param name="HoledPolys">The set to recieve the result.</param>
        /// <param name="bThisInside">The flag to indicate routes inside.</param>
        /// <param name="bOtherInside">The flag to indicate routes inside for the other.</param>
        /// <param name="grid">The degenerate settings.</param>
        public void GetBoolean(C2DPolyBase Other, List <C2DHoledPolyBase> HoledPolys,
                               bool bThisInside, bool bOtherInside,
                               CGrid grid)
        {
            if (BoundingRect.Overlaps(Other.BoundingRect))
            {
                switch (grid.DegenerateHandling)
                {
                case CGrid.eDegenerateHandling.None:
                {
                    var Routes1 = new C2DLineBaseSetSet();
                    var Routes2 = new C2DLineBaseSetSet();
                    C2DPolyBase.GetRoutes(this, bThisInside, Other, bOtherInside, Routes1, Routes2);
                    Routes1.ExtractAllOf(Routes2);

                    if (Routes1.Count > 0)
                    {
                        // Add all the joining routes together to form closed routes
                        Routes1.MergeJoining();
                        // Set up some temporary polygons.
                        var Polygons = new List <C2DPolyBase>();
                        // Turn the routes into polygons.
                        for (var i = Routes1.Count - 1; i >= 0; i--)
                        {
                            if (Routes1[i].IsClosed(true) && Routes1[i].Count > 2)
                            {
                                Polygons.Add(new C2DPolyBase());
                                Polygons[Polygons.Count - 1].CreateDirect(Routes1[i]);
                            }
                            else
                            {
                                //   Debug.Assert(false);
                                grid.LogDegenerateError();
                            }
                        }


                        // Set up some temporary holed polygons
                        var NewComPolys = new C2DHoledPolyBaseSet();
                        // Turn the set of polygons into holed polygons. Not needed for intersection.
                        if (!(bThisInside && bOtherInside))
                        {
                            C2DHoledPolyBase.PolygonsToHoledPolygons(NewComPolys, Polygons);
                            if (NewComPolys.Count != 1)
                            {
                                //   Debug.Assert(false);
                                grid.LogDegenerateError();
                            }
                        }
                        else
                        {
                            for (var i = 0; i < Polygons.Count; i++)
                            {
                                HoledPolys.Add(new C2DHoledPolyBase(Polygons[i]));
                            }
                        }

                        // Now add them all to the provided set.
                        for (var i = 0; i < NewComPolys.Count; i++)
                        {
                            HoledPolys.Add(NewComPolys[i]);
                        }
                    }
                }
                break;

                case CGrid.eDegenerateHandling.RandomPerturbation:
                {
                    var OtherCopy = new C2DPolyBase(Other);
                    OtherCopy.RandomPerturb();
                    grid.DegenerateHandling = CGrid.eDegenerateHandling.None;
                    GetBoolean(OtherCopy, HoledPolys, bThisInside, bOtherInside, grid);
                    grid.DegenerateHandling = CGrid.eDegenerateHandling.RandomPerturbation;
                }
                break;

                case CGrid.eDegenerateHandling.DynamicGrid:
                {
                    var Rect = new C2DRect();
                    if (this.BoundingRect.Overlaps(Other.BoundingRect, Rect))
                    {
                        var dOldGrid = grid.GridSize;
                        grid.SetToMinGridSize(Rect, false);
                        grid.DegenerateHandling = CGrid.eDegenerateHandling.PreDefinedGrid;
                        GetBoolean(Other, HoledPolys, bThisInside, bOtherInside, grid);
                        grid.DegenerateHandling = CGrid.eDegenerateHandling.DynamicGrid;
                    }
                }
                break;

                case CGrid.eDegenerateHandling.PreDefinedGrid:
                {
                    var P1 = new C2DPolyBase(this);
                    var P2 = new C2DPolyBase(Other);
                    P1.SnapToGrid(grid);
                    P2.SnapToGrid(grid);
                    var V1            = new C2DVector(P1.BoundingRect.TopLeft, P2.BoundingRect.TopLeft);
                    var dPerturbation = grid.GridSize;                     // ensure it snaps back to original grid positions.
                    if (V1.i > 0)
                    {
                        V1.i = dPerturbation;
                    }
                    else
                    {
                        V1.i = -dPerturbation;          // move away slightly if possible
                    }
                    if (V1.j > 0)
                    {
                        V1.j = dPerturbation;
                    }
                    else
                    {
                        V1.j = -dPerturbation;     // move away slightly if possible
                    }
                    V1.i *= 0.411923;              // ensure it snaps back to original grid positions.
                    V1.j *= 0.313131;              // ensure it snaps back to original grid positions.

                    P2.Move(V1);
                    grid.DegenerateHandling = CGrid.eDegenerateHandling.None;
                    P1.GetBoolean(P2, HoledPolys, bThisInside, bOtherInside, grid);

                    for (var i = 0; i < HoledPolys.Count; i++)
                    {
                        HoledPolys[i].SnapToGrid(grid);
                    }

                    grid.DegenerateHandling = CGrid.eDegenerateHandling.PreDefinedGrid;
                }
                break;

                case CGrid.eDegenerateHandling.PreDefinedGridPreSnapped:
                {
                    var P2            = new C2DPolyBase(Other);
                    var V1            = new C2DVector(this.BoundingRect.TopLeft, P2.BoundingRect.TopLeft);
                    var dPerturbation = grid.GridSize;                     // ensure it snaps back to original grid positions.
                    if (V1.i > 0)
                    {
                        V1.i = dPerturbation;
                    }
                    else
                    {
                        V1.i = -dPerturbation;     // move away slightly if possible
                    }
                    if (V1.j > 0)
                    {
                        V1.j = dPerturbation;
                    }
                    else
                    {
                        V1.j = -dPerturbation;     // move away slightly if possible
                    }
                    V1.i *= 0.411923;              // ensure it snaps back to original grid positions.
                    V1.j *= 0.313131;              // ensure it snaps back to original grid positions.

                    P2.Move(V1);
                    grid.DegenerateHandling = CGrid.eDegenerateHandling.None;
                    GetBoolean(P2, HoledPolys, bThisInside, bOtherInside, grid);

                    for (var i = 0; i < HoledPolys.Count; i++)
                    {
                        HoledPolys[i].SnapToGrid(grid);
                    }
                    grid.DegenerateHandling = CGrid.eDegenerateHandling.PreDefinedGridPreSnapped;
                }
                break;
                }
            }
        }