public Point2DList(Point2DList l)
        {
            int numPoints = l.Count;

            for (int i = 0; i < numPoints; ++i)
            {
                mPoints.Add(l [i]);
            }
            mBoundingBox.Set(l.BoundingBox);
            mEpsilon      = l.Epsilon;
            mWindingOrder = l.WindingOrder;
        }
        // From Eric Jordan's convex decomposition library
        /// <summary>
        /// Merges all parallel edges in the list of vertices
        /// </summary>
        /// <param name="tolerance"></param>
        public void MergeParallelEdges(double tolerance)
        {
            if (Count <= 3)
            {
                // Can't do anything useful here to a triangle
                return;
            }

            bool[] mergeMe      = new bool[Count];
            int    newNVertices = Count;

            //Gather points to process
            for (int i = 0; i < Count; ++i)
            {
                int lower  = (i == 0) ? (Count - 1) : (i - 1);
                int middle = i;
                int upper  = (i == Count - 1) ? (0) : (i + 1);

                double dx0   = this [middle].X - this [lower].X;
                double dy0   = this [middle].Y - this [lower].Y;
                double dx1   = this [upper].Y - this [middle].X;
                double dy1   = this [upper].Y - this [middle].Y;
                double norm0 = Math.Sqrt(dx0 * dx0 + dy0 * dy0);
                double norm1 = Math.Sqrt(dx1 * dx1 + dy1 * dy1);

                if (!(norm0 > 0.0 && norm1 > 0.0) && newNVertices > 3)
                {
                    //Merge identical points
                    mergeMe [i] = true;
                    --newNVertices;
                }

                dx0 /= norm0;
                dy0 /= norm0;
                dx1 /= norm1;
                dy1 /= norm1;
                double cross = dx0 * dy1 - dx1 * dy0;
                double dot   = dx0 * dx1 + dy0 * dy1;

                if (Math.Abs(cross) < tolerance && dot > 0 && newNVertices > 3)
                {
                    mergeMe [i] = true;
                    --newNVertices;
                }
                else
                {
                    mergeMe [i] = false;
                }
            }

            if (newNVertices == Count || newNVertices == 0)
            {
                return;
            }

            int currIndex = 0;

            // Copy the vertices to a new list and clear the old
            Point2DList oldVertices = new Point2DList(this);

            Clear();

            for (int i = 0; i < oldVertices.Count; ++i)
            {
                if (mergeMe [i] || newNVertices == 0 || currIndex == newNVertices)
                {
                    continue;
                }

                if (currIndex >= newNVertices)
                {
                    throw new Exception("Point2DList::MergeParallelEdges - currIndex[ " + currIndex.ToString() + "] >= newNVertices[" + newNVertices + "]");
                }

                mPoints.Add(oldVertices [i]);
                mBoundingBox.AddPoint(oldVertices [i]);
                ++currIndex;
            }
            mWindingOrder = CalculateWindingOrder();
            mEpsilon      = CalculateEpsilon();
        }
        /// <summary>
        /// Checks if polygon is valid for use in Box2d engine.
        /// Last ditch effort to ensure no invalid polygons are
        /// added to world geometry.
        ///
        /// Performs a full check, for simplicity, convexity,
        /// orientation, minimum angle, and volume.  This won't
        /// be very efficient, and a lot of it is redundant when
        /// other tools in this section are used.
        ///
        /// From Eric Jordan's convex decomposition library
        /// </summary>
        /// <param name="printErrors"></param>
        /// <returns></returns>
        public PolygonError CheckPolygon()
        {
            PolygonError error = PolygonError.None;

            if (Count < 3 || Count > Point2DList.kMaxPolygonVertices)
            {
                error |= PolygonError.NotEnoughVertices;
                // no other tests will be valid at this point, so just return
                return(error);
            }
            if (IsDegenerate())
            {
                error |= PolygonError.Degenerate;
            }
            //bool bIsConvex = IsConvex();
            //if (!IsConvex())
            //{
            //    error |= PolygonError.NotConvex;
            //}
            if (!IsSimple())
            {
                error |= PolygonError.NotSimple;
            }
            if (GetArea() < MathUtil.EPSILON)
            {
                error |= PolygonError.AreaTooSmall;
            }

            // the following tests don't make sense if the polygon is not simple
            if ((error & PolygonError.NotSimple) != PolygonError.NotSimple)
            {
                bool             bReversed            = false;
                WindingOrderType expectedWindingOrder = WindingOrderType.CCW;
                WindingOrderType reverseWindingOrder  = WindingOrderType.CW;
                if (WindingOrder == reverseWindingOrder)
                {
                    WindingOrder = expectedWindingOrder;
                    bReversed    = true;
                }

                //Compute normals
                Point2D[]   normals  = new Point2D[Count];
                Point2DList vertices = new Point2DList(Count);
                for (int i = 0; i < Count; ++i)
                {
                    vertices.Add(new Point2D(this [i].X, this [i].Y));
                    int     i1   = i;
                    int     i2   = NextIndex(i);
                    Point2D edge = new Point2D(this [i2].X - this [i1].X, this [i2].Y - this [i1].Y);
                    normals [i] = Point2D.Perpendicular(edge, 1.0);
                    normals [i].Normalize();
                }

                //Required side checks
                for (int i = 0; i < Count; ++i)
                {
                    int iminus = PreviousIndex(i);

                    //Parallel sides check
                    double cross = Point2D.Cross(normals [iminus], normals [i]);
                    cross = MathUtil.Clamp(cross, -1.0f, 1.0f);
                    float angle = (float)Math.Asin(cross);
                    if (Math.Abs(angle) <= Point2DList.kAngularSlop)
                    {
                        error |= PolygonError.SidesTooCloseToParallel;
                        break;
                    }

                    // For some reason, the following checks do not seem to work
                    // correctly in all cases - they return false positives.
                    //    //Too skinny check - only valid for convex polygons
                    //    if (bIsConvex)
                    //    {
                    //        for (int j = 0; j < Count; ++j)
                    //        {
                    //            if (j == i || j == NextIndex(i))
                    //            {
                    //                continue;
                    //            }
                    //            Point2D testVector = vertices[j] - vertices[i];
                    //            testVector.Normalize();
                    //            double s = Point2D.Dot(testVector, normals[i]);
                    //            if (s >= -Point2DList.kLinearSlop)
                    //            {
                    //                error |= PolygonError.TooThin;
                    //            }
                    //        }

                    //        Point2D centroid = vertices.GetCentroid();
                    //        Point2D n1 = normals[iminus];
                    //        Point2D n2 = normals[i];
                    //        Point2D v = vertices[i] - centroid;

                    //        Point2D d = new Point2D();
                    //        d.X = Point2D.Dot(n1, v); // - toiSlop;
                    //        d.Y = Point2D.Dot(n2, v); // - toiSlop;

                    //        // Shifting the edge inward by toiSlop should
                    //        // not cause the plane to pass the centroid.
                    //        if ((d.X < 0.0f) || (d.Y < 0.0f))
                    //        {
                    //            error |= PolygonError.TooThin;
                    //        }
                    //    }
                }

                if (bReversed)
                {
                    WindingOrder = reverseWindingOrder;
                }
            }

            //if (error != PolygonError.None)
            //{
            //    Console.WriteLine("Found invalid polygon: {0} {1}\n", Point2DList.GetErrorString(error), this.ToString());
            //}

            return(error);
        }
 public virtual void AddRange(Point2DList l)
 {
     AddRange(l.mPoints.GetEnumerator(), l.WindingOrder);
 }
        public static void InitializeHoles(List <Contour> holes, ITriangulatable parent, ConstrainedPointSet cps)
        {
            int numHoles = holes.Count;
            int holeIdx  = 0;

            // pass 1 - remove duplicates
            while (holeIdx < numHoles)
            {
                int hole2Idx = holeIdx + 1;
                while (hole2Idx < numHoles)
                {
                    bool bSamePolygon = PolygonUtil.PolygonsAreSame2D(holes [holeIdx], holes [hole2Idx]);
                    if (bSamePolygon)
                    {
                        // remove one of them
                        holes.RemoveAt(hole2Idx);
                        --numHoles;
                    }
                    else
                    {
                        ++hole2Idx;
                    }
                }
                ++holeIdx;
            }

            // pass 2: Intersections and Containment
            holeIdx = 0;
            while (holeIdx < numHoles)
            {
                bool bIncrementHoleIdx = true;
                int  hole2Idx          = holeIdx + 1;
                while (hole2Idx < numHoles)
                {
                    if (PolygonUtil.PolygonContainsPolygon(holes [holeIdx], holes [holeIdx].Bounds, holes [hole2Idx], holes [hole2Idx].Bounds, false))
                    {
                        holes [holeIdx].AddHole(holes [hole2Idx]);
                        holes.RemoveAt(hole2Idx);
                        --numHoles;
                    }
                    else if (PolygonUtil.PolygonContainsPolygon(holes [hole2Idx], holes [hole2Idx].Bounds, holes [holeIdx], holes [holeIdx].Bounds, false))
                    {
                        holes [hole2Idx].AddHole(holes [holeIdx]);
                        holes.RemoveAt(holeIdx);
                        --numHoles;
                        bIncrementHoleIdx = false;
                        break;
                    }
                    else
                    {
                        bool bIntersect = PolygonUtil.PolygonsIntersect2D(holes [holeIdx], holes [holeIdx].Bounds, holes [hole2Idx], holes [hole2Idx].Bounds);
                        if (bIntersect)
                        {
                            // this is actually an error condition
                            // fix by merging hole1 and hole2 into hole1 (including the holes inside hole2!) and delete hole2
                            // Then, because hole1 is now changed, restart it's check.
                            PolygonOperationContext ctx = new PolygonOperationContext();
                            if (!ctx.Init(PolygonUtil.PolyOperation.Union | PolygonUtil.PolyOperation.Intersect, holes [holeIdx], holes [hole2Idx]))
                            {
                                if (ctx.mError == PolygonUtil.PolyUnionError.Poly1InsidePoly2)
                                {
                                    holes [hole2Idx].AddHole(holes [holeIdx]);
                                    holes.RemoveAt(holeIdx);
                                    --numHoles;
                                    bIncrementHoleIdx = false;
                                    break;
                                }
                                else
                                {
                                    throw new Exception("PolygonOperationContext.Init had an error during initialization");
                                }
                            }
                            PolygonUtil.PolyUnionError pue = PolygonUtil.PolygonOperation(ctx);
                            if (pue == PolygonUtil.PolyUnionError.None)
                            {
                                Point2DList union        = ctx.Union;
                                Point2DList intersection = ctx.Intersect;

                                // create a new contour for the union
                                Contour c = new Contour(parent);
                                c.AddRange(union);
                                c.Name         = "(" + holes [holeIdx].Name + " UNION " + holes [hole2Idx].Name + ")";
                                c.WindingOrder = Point2DList.WindingOrderType.Default;

                                // add children from both of the merged contours
                                int numChildHoles = holes [holeIdx].GetNumHoles();
                                for (int i = 0; i < numChildHoles; ++i)
                                {
                                    c.AddHole(holes [holeIdx].GetHole(i));
                                }
                                numChildHoles = holes [hole2Idx].GetNumHoles();
                                for (int i = 0; i < numChildHoles; ++i)
                                {
                                    c.AddHole(holes [hole2Idx].GetHole(i));
                                }

                                // make sure we preserve the contours of the intersection
                                Contour cInt = new Contour(c);
                                cInt.AddRange(intersection);
                                cInt.Name         = "(" + holes [holeIdx].Name + " INTERSECT " + holes [hole2Idx].Name + ")";
                                cInt.WindingOrder = Point2DList.WindingOrderType.Default;
                                c.AddHole(cInt);

                                // replace the current contour with the merged contour
                                holes [holeIdx] = c;

                                // toss the second contour
                                holes.RemoveAt(hole2Idx);
                                --numHoles;

                                // current hole is "examined", so move to the next one
                                hole2Idx = holeIdx + 1;
                            }
                            else
                            {
                                throw new Exception("PolygonOperation had an error!");
                            }
                        }
                        else
                        {
                            ++hole2Idx;
                        }
                    }
                }
                if (bIncrementHoleIdx)
                {
                    ++holeIdx;
                }
            }

            numHoles = holes.Count;
            holeIdx  = 0;
            while (holeIdx < numHoles)
            {
                int numPoints = holes [holeIdx].Count;
                for (int i = 0; i < numPoints; ++i)
                {
                    int  j = holes [holeIdx].NextIndex(i);
                    uint constraintCode        = TriangulationConstraint.CalculateContraintCode(holes [holeIdx] [i], holes [holeIdx] [j]);
                    TriangulationConstraint tc = null;
                    if (!cps.TryGetConstraint(constraintCode, out tc))
                    {
                        tc = new TriangulationConstraint(holes [holeIdx] [i], holes [holeIdx] [j]);
                        cps.AddConstraint(tc);
                    }

                    // replace the points in the holes with valid points
                    if (holes [holeIdx] [i].VertexCode == tc.P.VertexCode)
                    {
                        holes [holeIdx] [i] = tc.P;
                    }
                    else if (holes [holeIdx] [j].VertexCode == tc.P.VertexCode)
                    {
                        holes [holeIdx] [j] = tc.P;
                    }
                    if (holes [holeIdx] [i].VertexCode == tc.Q.VertexCode)
                    {
                        holes [holeIdx] [i] = tc.Q;
                    }
                    else if (holes [holeIdx] [j].VertexCode == tc.Q.VertexCode)
                    {
                        holes [holeIdx] [j] = tc.Q;
                    }
                }
                ++holeIdx;
            }
        }