Update to Clipper 1.2+

Updates to Clipper2 742614f, which includes bug fixes for specific KiCad
boards beyond Clipper2 itself

Fixes https://gitlab.com/kicad/code/kicad/issues/14294

libs/kimath/include/geometry/shape_poly_set.h

@@ -1396,9 +1396,9 @@ private:
     void importPaths( Clipper2Lib::Paths64&               paths,
                      const std::vector<CLIPPER_Z_VALUE>& aZValueBuffer,
                      const std::vector<SHAPE_ARC>&       aArcBuffe );
-    void importPolyPath( Clipper2Lib::PolyPath64*        aPolyPath,
+    void importPolyPath( const std::unique_ptr<Clipper2Lib::PolyPath64>& aPolyPath,
-                     const std::vector<CLIPPER_Z_VALUE>& aZValueBuffer,
+                     const std::vector<CLIPPER_Z_VALUE>&                 aZValueBuffer,
-                     const std::vector<SHAPE_ARC>&       aArcBuffer );
+                     const std::vector<SHAPE_ARC>&                       aArcBuffer );
 
     void inflate1( int aAmount, int aCircleSegCount, CORNER_STRATEGY aCornerStrategy );
     void inflate2( int aAmount, int aCircleSegCount, CORNER_STRATEGY aCornerStrategy );

libs/kimath/src/geometry/shape_poly_set.cpp

@@ -1069,17 +1069,9 @@ void SHAPE_POLY_SET::inflate2( int aAmount, int aCircleSegCount, CORNER_STRATEGY
 
     c.ArcTolerance( std::abs( aAmount ) * coeff );
     c.MiterLimit( miterLimit );
-    c.MergeGroups( true );
-    Paths64 solution = c.Execute( aAmount );
 
-    // We get paths back but we need the tree to assign the holes to the correct
-    // outlines
-    Clipper64 c2;
     PolyTree64 tree;
-    c2.PreserveCollinear = false;
+    c.Execute( aAmount, tree );
-    c2.ReverseSolution = false;
-    c2.AddSubject( solution );
-    c2.Execute(ClipType::Union, FillRule::Positive, tree);
 
     importTree( tree, zValues, arcBuffer );
     tree.Clear();
@@ -1119,9 +1111,9 @@ void SHAPE_POLY_SET::importTree( ClipperLib::PolyTree*               tree,
 }
 
 
-void SHAPE_POLY_SET::importPolyPath( Clipper2Lib::PolyPath64*            aPolyPath,
+void SHAPE_POLY_SET::importPolyPath( const std::unique_ptr<Clipper2Lib::PolyPath64>& aPolyPath,
-                                     const std::vector<CLIPPER_Z_VALUE>& aZValueBuffer,
+                                     const std::vector<CLIPPER_Z_VALUE>&             aZValueBuffer,
-                                     const std::vector<SHAPE_ARC>&       aArcBuffer )
+                                     const std::vector<SHAPE_ARC>&                   aArcBuffer )
 {
     if( !aPolyPath->IsHole() )
     {
@@ -1129,11 +1121,11 @@ void SHAPE_POLY_SET::importPolyPath( Clipper2Lib::PolyPath64*            aPolyPa
         paths.reserve( aPolyPath->Count() + 1 );
         paths.emplace_back( aPolyPath->Polygon(), aZValueBuffer, aArcBuffer );
 
-        for( Clipper2Lib::PolyPath64* child : *aPolyPath )
+        for( const std::unique_ptr<Clipper2Lib::PolyPath64>& child : *aPolyPath )
         {
             paths.emplace_back( child->Polygon(), aZValueBuffer, aArcBuffer );
 
-            for( Clipper2Lib::PolyPath64* grandchild : *child )
+            for( const std::unique_ptr<Clipper2Lib::PolyPath64>& grandchild : *child )
                 importPolyPath( grandchild, aZValueBuffer, aArcBuffer );
         }
 
@@ -1148,7 +1140,7 @@ void SHAPE_POLY_SET::importTree( Clipper2Lib::PolyTree64&            tree,
 {
     m_polys.clear();
 
-    for( Clipper2Lib::PolyPath64* n : tree )
+    for( const std::unique_ptr<Clipper2Lib::PolyPath64>& n : tree )
         importPolyPath( n, aZValueBuffer, aArcBuffer );
 }
 

thirdparty/clipper2/Clipper2Lib/include/clipper2/clipper.engine.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  26 October 2022                                                 *
+* Date      :  2 March 2023                                                    *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  This is the main polygon clipping module                        *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -10,13 +10,16 @@
 #ifndef CLIPPER_ENGINE_H
 #define CLIPPER_ENGINE_H
 
-#define CLIPPER2_VERSION "1.0.6"
+constexpr auto CLIPPER2_VERSION = "1.2.1";
 
 #include <cstdlib>
+#include <iostream>
 #include <queue>
-#include <stdexcept>
 #include <vector>
 #include <functional>
+#include <numeric>
+#include <memory>
+
 #include "clipper.core.h"
 
 #ifdef None
@@ -31,12 +34,13 @@ namespace Clipper2Lib {
 	struct Vertex;
 	struct LocalMinima;
 	struct OutRec;
-	struct Joiner;
+	struct HorzSegment;
 
 	//Note: all clipping operations except for Difference are commutative.
 	enum class ClipType { None, Intersection, Union, Difference, Xor };
 	
 	enum class PathType { Subject, Clip };
+	enum class JoinWith { None, Left, Right };
 
 	enum class VertexFlags : uint32_t {
 		None = 0, OpenStart = 1, OpenEnd = 2, LocalMax = 4, LocalMin = 8
@@ -47,7 +51,7 @@ namespace Clipper2Lib {
 		return (enum VertexFlags)(uint32_t(a) & uint32_t(b));
 	}
 
-	constexpr enum VertexFlags operator |(enum VertexFlags a, enum VertexFlags b) 
+	constexpr enum VertexFlags operator |(enum VertexFlags a, enum VertexFlags b)
 	{
 		return (enum VertexFlags)(uint32_t(a) | uint32_t(b));
 	}
@@ -64,7 +68,7 @@ namespace Clipper2Lib {
 		OutPt*	next = nullptr;
 		OutPt*	prev = nullptr;
 		OutRec* outrec;
-		Joiner* joiner = nullptr;
+		HorzSegment* horz = nullptr;
 
 		OutPt(const Point64& pt_, OutRec* outrec_): pt(pt_), outrec(outrec_) {
 			next = this;
@@ -86,15 +90,20 @@ namespace Clipper2Lib {
 	struct OutRec {
 		size_t idx = 0;
 		OutRec* owner = nullptr;
-		OutRecList* splits = nullptr;
 		Active* front_edge = nullptr;
 		Active* back_edge = nullptr;
 		OutPt* pts = nullptr;
 		PolyPath* polypath = nullptr;
+		OutRecList* splits = nullptr;
 		Rect64 bounds = {};
 		Path64 path;
 		bool is_open = false;
-		~OutRec() { if (splits) delete splits; };
+		bool horz_done = false;
+		~OutRec() { 
+			if (splits) delete splits;
+			// nb: don't delete the split pointers
+			// as these are owned by ClipperBase's outrec_list_
+		};
 	};
 
 	///////////////////////////////////////////////////////////////////
@@ -126,6 +135,7 @@ namespace Clipper2Lib {
 		Vertex* vertex_top = nullptr;
 		LocalMinima* local_min = nullptr;  // the bottom of an edge 'bound' (also Vatti)
 		bool is_left_bound = false;
+		JoinWith join_with = JoinWith::None;
 	};
 
 	struct LocalMinima {
@@ -140,11 +150,24 @@ namespace Clipper2Lib {
 		Point64 pt;
 		Active* edge1;
 		Active* edge2;
-		IntersectNode() : pt(Point64(0, 0)), edge1(NULL), edge2(NULL) {}
+		IntersectNode() : pt(Point64(0,0)), edge1(NULL), edge2(NULL) {}
 			IntersectNode(Active* e1, Active* e2, Point64& pt_) :
-			pt(pt_), edge1(e1), edge2(e2)
+			pt(pt_), edge1(e1), edge2(e2) {}
-		{
+	};
-		}
+
+	struct HorzSegment {
+		OutPt* left_op;
+		OutPt* right_op = nullptr;
+		bool left_to_right = true;
+		HorzSegment() : left_op(nullptr) { }
+		explicit HorzSegment(OutPt* op) : left_op(op) { }
+	};
+
+	struct HorzJoin {
+		OutPt* op1 = nullptr;
+		OutPt* op2 = nullptr;
+		HorzJoin() {};
+		explicit HorzJoin(OutPt* ltr, OutPt* rtl) : op1(ltr), op2(rtl) { }
 	};
 
 #ifdef USINGZ
@@ -155,6 +178,11 @@ namespace Clipper2Lib {
 		const PointD& e2bot, const PointD& e2top, PointD& pt)> ZCallbackD;
 #endif
 
+	typedef std::vector<HorzSegment> HorzSegmentList;
+	typedef std::unique_ptr<LocalMinima> LocalMinima_ptr;
+	typedef std::vector<LocalMinima_ptr> LocalMinimaList;
+	typedef std::vector<IntersectNode> IntersectNodeList;
+
 	// ClipperBase -------------------------------------------------------------
 
 	class ClipperBase {
@@ -167,21 +195,21 @@ namespace Clipper2Lib {
 		bool using_polytree_ = false;
 		Active* actives_ = nullptr;
 		Active *sel_ = nullptr;
-		Joiner *horz_joiners_ = nullptr;
+		LocalMinimaList minima_list_;		//pointers in case of memory reallocs
-		std::vector<LocalMinima*> minima_list_;		//pointers in case of memory reallocs
+		LocalMinimaList::iterator current_locmin_iter_;
-		std::vector<LocalMinima*>::iterator current_locmin_iter_;
 		std::vector<Vertex*> vertex_lists_;
 		std::priority_queue<int64_t> scanline_list_;
-		std::vector<IntersectNode> intersect_nodes_; 
+		IntersectNodeList intersect_nodes_;
-		std::vector<Joiner*> joiner_list_;				//pointers in case of memory reallocs
+    HorzSegmentList horz_seg_list_;
+		std::vector<HorzJoin> horz_join_list_;
 		void Reset();
-		void InsertScanline(int64_t y);
+		inline void InsertScanline(int64_t y);
-		bool PopScanline(int64_t &y);
+		inline bool PopScanline(int64_t &y);
-		bool PopLocalMinima(int64_t y, LocalMinima *&local_minima);
+		inline bool PopLocalMinima(int64_t y, LocalMinima*& local_minima);
 		void DisposeAllOutRecs();
 		void DisposeVerticesAndLocalMinima();
 		void DeleteEdges(Active*& e);
-		void AddLocMin(Vertex &vert, PathType polytype, bool is_open);
+		inline void AddLocMin(Vertex &vert, PathType polytype, bool is_open);
 		bool IsContributingClosed(const Active &e) const;
 		inline bool IsContributingOpen(const Active &e) const;
 		void SetWindCountForClosedPathEdge(Active &edge);
@@ -200,38 +228,40 @@ namespace Clipper2Lib {
 		bool BuildIntersectList(const int64_t top_y);
 		void ProcessIntersectList();
 		void SwapPositionsInAEL(Active& edge1, Active& edge2);
+		OutRec* NewOutRec();
 		OutPt* AddOutPt(const Active &e, const Point64& pt);
 		OutPt* AddLocalMinPoly(Active &e1, Active &e2, 
 			const Point64& pt, bool is_new = false);
 		OutPt* AddLocalMaxPoly(Active &e1, Active &e2, const Point64& pt);
 		void DoHorizontal(Active &horz);
-		bool ResetHorzDirection(const Active &horz, const Active *max_pair,
+		bool ResetHorzDirection(const Active &horz, const Vertex* max_vertex,
 			int64_t &horz_left, int64_t &horz_right);
 		void DoTopOfScanbeam(const int64_t top_y);
 		Active *DoMaxima(Active &e);
 		void JoinOutrecPaths(Active &e1, Active &e2);
 		void CompleteSplit(OutPt* op1, OutPt* op2, OutRec& outrec);
-		bool ValidateClosedPathEx(OutPt*& outrec);
-		void CleanCollinear(OutRec* outrec);
 		void FixSelfIntersects(OutRec* outrec);
-		OutPt* DoSplitOp(OutPt* outRecOp, OutPt* splitOp);
+		void DoSplitOp(OutRec* outRec, OutPt* splitOp);
-		Joiner* GetHorzTrialParent(const OutPt* op);
+		
-		bool OutPtInTrialHorzList(OutPt* op);
+		inline void AddTrialHorzJoin(OutPt* op);
-		void SafeDisposeOutPts(OutPt*& op);
+		void ConvertHorzSegsToJoins();
-		void SafeDeleteOutPtJoiners(OutPt* op);
+		void ProcessHorzJoins();
-		void AddTrialHorzJoin(OutPt* op);
+
-		void DeleteTrialHorzJoin(OutPt* op);
+		void Split(Active& e, const Point64& pt);
-		void ConvertHorzTrialsToJoins();
+		inline void CheckJoinLeft(Active& e, 
-		void AddJoin(OutPt* op1, OutPt* op2);
+			const Point64& pt, bool check_curr_x = false);
-		void DeleteJoin(Joiner* joiner);
+		inline void CheckJoinRight(Active& e,
-		void ProcessJoinerList();
+			const Point64& pt, bool check_curr_x = false);
-		OutRec* ProcessJoin(Joiner* joiner);
 	protected:
+		int error_code_ = 0;
 		bool has_open_paths_ = false;
 		bool succeeded_ = true;
-		std::vector<OutRec*> outrec_list_; //pointers in case list memory reallocated
+		OutRecList outrec_list_; //pointers in case list memory reallocated
 		bool ExecuteInternal(ClipType ct, FillRule ft, bool use_polytrees);
-		bool DeepCheckOwner(OutRec* outrec, OutRec* owner);
+		void CleanCollinear(OutRec* outrec);
+		bool CheckBounds(OutRec* outrec);
+		void RecursiveCheckOwners(OutRec* outrec, PolyPath* polypath);
+		void DeepCheckOwners(OutRec* outrec, PolyPath* polypath);
 #ifdef USINGZ
 		ZCallback64 zCallback_ = nullptr;
 		void SetZ(const Active& e1, const Active& e2, Point64& pt);
@@ -241,9 +271,13 @@ namespace Clipper2Lib {
 		void AddPaths(const Paths64& paths, PathType polytype, bool is_open);
 	public:
 		virtual ~ClipperBase();
+		int ErrorCode() { return error_code_; };
 		bool PreserveCollinear = true;
 		bool ReverseSolution = false;
 		void Clear();
+#ifdef USINGZ
+		int64_t DefaultZ = 0;
+#endif
 	};
 
 	// PolyPath / PolyTree --------------------------------------------------------
@@ -258,7 +292,7 @@ namespace Clipper2Lib {
 		PolyPath* parent_;
 	public:
 		PolyPath(PolyPath* parent = nullptr): parent_(parent){}
-		virtual ~PolyPath() { Clear(); };		
+		virtual ~PolyPath() {};
 		//https://en.cppreference.com/w/cpp/language/rule_of_three
 		PolyPath(const PolyPath&) = delete;
 		PolyPath& operator=(const PolyPath&) = delete;
@@ -273,145 +307,131 @@ namespace Clipper2Lib {
 
 		virtual PolyPath* AddChild(const Path64& path) = 0;
 
-		virtual void Clear() {};
+		virtual void Clear() = 0;
 		virtual size_t Count() const { return 0; }
 
 		const PolyPath* Parent() const { return parent_; }
 
 		bool IsHole() const 
 		{
-			const PolyPath* pp = parent_;
+			unsigned lvl = Level();
-			bool is_hole = pp;
+			//Even levels except level 0
-			while (pp) {
+			return lvl && !(lvl & 1);
-				is_hole = !is_hole;
+		}		
-				pp = pp->parent_;
-			}
-			return is_hole;
-		}
 	};
 
+	typedef typename std::vector<std::unique_ptr<PolyPath64>> PolyPath64List;
+	typedef typename std::vector<std::unique_ptr<PolyPathD>>  PolyPathDList;
+
 	class PolyPath64 : public PolyPath {
 	private:
-		std::vector<PolyPath64*> childs_;
+		PolyPath64List childs_;
 		Path64 polygon_;
-		typedef typename std::vector<PolyPath64*>::const_iterator pp64_itor;
 	public:
-		PolyPath64(PolyPath64* parent = nullptr) : PolyPath(parent) {}
+		explicit PolyPath64(PolyPath64* parent = nullptr) : PolyPath(parent) {}
-		PolyPath64* operator [] (size_t index) { return static_cast<PolyPath64*>(childs_[index]); }
+
-		pp64_itor begin() const { return childs_.cbegin(); }
+		~PolyPath64() {
-		pp64_itor end() const { return childs_.cend(); }
+			childs_.resize(0);
+		}
+
+		const PolyPath64* operator [] (size_t index) const
+		{ 
+			return childs_[index].get(); 
+		} 
+
+		const PolyPath64* Child(size_t index) const
+		{
+			return childs_[index].get();
+		}
+
+		PolyPath64List::const_iterator begin() const { return childs_.cbegin(); }
+		PolyPath64List::const_iterator end() const { return childs_.cend(); }
 
 		PolyPath64* AddChild(const Path64& path) override
 		{
-			PolyPath64* result = new PolyPath64(this);
+			auto p = std::make_unique<PolyPath64>(this);
-			childs_.push_back(result);
+			auto* result = childs_.emplace_back(std::move(p)).get();
 			result->polygon_ = path;
 			return result;
 		}
 
 		void Clear() override
 		{
-			for (PolyPath64* child : childs_)
-			{
-			    child->Clear();
-			    delete child;
-			}
 			childs_.resize(0);
 		}
 
-		size_t Count() const  override
+		size_t Count() const override
 		{
 			return childs_.size();
 		}
 
-		const Path64 Polygon() const { return polygon_; };
+		const Path64& Polygon() const { return polygon_; };
 
 		double Area() const
 		{
-			double result = Clipper2Lib::Area<int64_t>(polygon_);
+			return std::accumulate(childs_.cbegin(), childs_.cend(),
-			for (const PolyPath64* child : childs_)
+				Clipper2Lib::Area<int64_t>(polygon_),
-				result += child->Area();
+				[](double a, const auto& child) {return a + child->Area(); });
-			return result;
-		}
-
-		friend std::ostream& operator << (std::ostream& outstream, const PolyPath64& polypath)
-		{
-			const size_t level_indent = 4;
-			const size_t coords_per_line = 4;
-			const size_t last_on_line = coords_per_line - 1;
-			unsigned level = polypath.Level();
-			if (level > 0)
-			{
-				std::string level_padding;
-				level_padding.insert(0, (level - 1) * level_indent, ' ');
-				std::string caption = polypath.IsHole() ? "Hole " : "Outer Polygon ";
-				std::string childs = polypath.Count() == 1 ? " child" : " children";
-				outstream << level_padding.c_str() << caption << "with " << polypath.Count() << childs << std::endl;
-				outstream << level_padding;
-				size_t i = 0, highI = polypath.Polygon().size() - 1;
-				for (; i < highI; ++i)
-				{
-					outstream << polypath.Polygon()[i] << ' ';
-					if ((i % coords_per_line) == last_on_line)
-						outstream << std::endl << level_padding;
-				}
-				if (highI > 0) outstream << polypath.Polygon()[i];
-				outstream << std::endl;
-			}
-			for (auto child : polypath)
-				outstream << *child;
-			return outstream;
 		}
 
 	};
 
 	class PolyPathD : public PolyPath {
 	private:
-		std::vector<PolyPathD*> childs_;
+		PolyPathDList childs_;
 		double inv_scale_;
 		PathD polygon_;
-		typedef typename std::vector<PolyPathD*>::const_iterator ppD_itor;
 	public:
-		PolyPathD(PolyPathD* parent = nullptr) : PolyPath(parent) 
+		explicit PolyPathD(PolyPathD* parent = nullptr) : PolyPath(parent)
 		{
 			inv_scale_ = parent ? parent->inv_scale_ : 1.0;
 		}
-		PolyPathD* operator [] (size_t index) 
+
-		{ 
+		~PolyPathD() {
-			return static_cast<PolyPathD*>(childs_[index]); 
+			childs_.resize(0);
 		}
-		ppD_itor begin() const { return childs_.cbegin(); }
+
-		ppD_itor end() const { return childs_.cend(); }
+		const PolyPathD* operator [] (size_t index) const
+		{ 
+			return childs_[index].get();
+		}
+
+		const PolyPathD* Child(size_t index) const
+		{
+			return childs_[index].get();
+		}
+
+		PolyPathDList::const_iterator begin() const { return childs_.cbegin(); }
+		PolyPathDList::const_iterator end() const { return childs_.cend(); }
 
 		void SetInvScale(double value) { inv_scale_ = value; }
 		double InvScale() { return inv_scale_; }
 		PolyPathD* AddChild(const Path64& path) override
 		{
-			PolyPathD* result = new PolyPathD(this);
+			int error_code = 0;
-			childs_.push_back(result);
+			auto p = std::make_unique<PolyPathD>(this);
-			result->polygon_ = ScalePath<double, int64_t>(path, inv_scale_);
+			PolyPathD* result = childs_.emplace_back(std::move(p)).get();
+			result->polygon_ = ScalePath<double, int64_t>(path, inv_scale_, error_code);
 			return result;
 		}
 
 		void Clear() override
 		{
-			for (const PolyPathD* child : childs_) delete child;
 			childs_.resize(0);
 		}
 
-		size_t Count() const  override
+		size_t Count() const override
 		{
 			return childs_.size();
 		}
 
-		const PathD Polygon() const { return polygon_; };
+		const PathD& Polygon() const { return polygon_; };
 
 		double Area() const
 		{
-			double result = Clipper2Lib::Area<double>(polygon_);
+			return std::accumulate(childs_.begin(), childs_.end(),
-			for (const PolyPathD* child : childs_)
+				Clipper2Lib::Area<double>(polygon_),
-				result += child->Area();
+				[](double a, const auto& child) {return a + child->Area(); });
-			return result;
 		}
 	};
 
@@ -451,7 +471,7 @@ namespace Clipper2Lib {
 			closed_paths.clear();
 			open_paths.clear();
 			if (ExecuteInternal(clip_type, fill_rule, false))
-				BuildPaths64(closed_paths, &open_paths);
+					BuildPaths64(closed_paths, &open_paths);
 			CleanUp();
 			return succeeded_;
 		}
@@ -480,19 +500,23 @@ namespace Clipper2Lib {
 	private:
 		double scale_ = 1.0, invScale_ = 1.0;
 #ifdef USINGZ
-		ZCallbackD zCallback_ = nullptr;
+		ZCallbackD zCallbackD_ = nullptr;
 #endif
 		void BuildPathsD(PathsD& solutionClosed, PathsD* solutionOpen);
 		void BuildTreeD(PolyPathD& polytree, PathsD& open_paths);
 	public:
 		explicit ClipperD(int precision = 2) : ClipperBase()
 		{
-			scale_ = std::pow(10, precision);
+			CheckPrecision(precision, error_code_);
+			// to optimize scaling / descaling precision
+			// set the scale to a power of double's radix (2) (#25)
+			scale_ = std::pow(std::numeric_limits<double>::radix,
+				std::ilogb(std::pow(10, precision)) + 1);
 			invScale_ = 1 / scale_;
 		}
 
 #ifdef USINGZ
-		void SetZCallback(ZCallbackD cb) { zCallback_ = cb; };
+		void SetZCallback(ZCallbackD cb) { zCallbackD_ = cb; };
 
 		void ZCB(const Point64& e1bot, const Point64& e1top,
 			const Point64& e2bot, const Point64& e2top, Point64& pt)
@@ -506,13 +530,13 @@ namespace Clipper2Lib {
 			PointD e1t = PointD(e1top) * invScale_;
 			PointD e2b = PointD(e2bot) * invScale_;
 			PointD e2t = PointD(e2top) * invScale_;
-			zCallback_(e1b,e1t, e2b, e2t, tmp);
+			zCallbackD_(e1b,e1t, e2b, e2t, tmp);
 			pt.z = tmp.z; // only update 'z'
 		};
 
 		void CheckCallback()
 		{
-			if(zCallback_)
+			if(zCallbackD_)
 				// if the user defined float point callback has been assigned 
 				// then assign the proxy callback function
 				ClipperBase::zCallback_ = 
@@ -527,17 +551,17 @@ namespace Clipper2Lib {
 
 		void AddSubject(const PathsD& subjects)
 		{
-			AddPaths(ScalePaths<int64_t, double>(subjects, scale_), PathType::Subject, false);
+			AddPaths(ScalePaths<int64_t, double>(subjects, scale_, error_code_), PathType::Subject, false);
 		}
 
 		void AddOpenSubject(const PathsD& open_subjects)
 		{
-			AddPaths(ScalePaths<int64_t, double>(open_subjects, scale_), PathType::Subject, true);
+			AddPaths(ScalePaths<int64_t, double>(open_subjects, scale_, error_code_), PathType::Subject, true);
 		}
 
 		void AddClip(const PathsD& clips)
 		{
-			AddPaths(ScalePaths<int64_t, double>(clips, scale_), PathType::Clip, false);
+			AddPaths(ScalePaths<int64_t, double>(clips, scale_, error_code_), PathType::Clip, false);
 		}
 
 		bool Execute(ClipType clip_type, FillRule fill_rule, PathsD& closed_paths)

thirdparty/clipper2/Clipper2Lib/include/clipper2/clipper.export.h

@@ -1,23 +1,23 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  28 October 2022                                                 *
+* Date      :  22 March 2023                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  This module exports the Clipper2 Library (ie DLL/so)            *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
 
 // The exported functions below refer to simple structures that
 // can be understood across multiple languages. Consequently
-// Path64, PathD, Polytree64 etc are converted from classes
+// Path64, PathD, Polytree64 etc are converted from C++ classes
 // (std::vector<> etc) into the following data structures:
 //
 // CPath64 (int64_t*) & CPathD (double_t*):
 // Path64 and PathD are converted into arrays of x,y coordinates.
 // However in these arrays the first x,y coordinate pair is a
 // counter with 'x' containing the number of following coordinate
-// pairs. ('y' must always be 0.)
+// pairs. ('y' should be 0, with one exception explained below.)
-//__________________________________
+// __________________________________
 // |counter|coord1|coord2|...|coordN|
 // |N ,0   |x1, y1|x2, y2|...|xN, yN|
 // __________________________________
@@ -25,19 +25,15 @@
 // CPaths64 (int64_t**) & CPathsD (double_t**):
 // These are arrays of pointers to CPath64 and CPathD where
 // the first pointer is to a 'counter path'. This 'counter
-// path' has a single x,y coord pair where 'y' contains
+// path' has a single x,y coord pair with 'y' (not 'x')
-// the number of paths that follow (and with 'x' always 0).
+// containing the number of paths that follow. ('x' = 0).
 // _______________________________
 // |counter|path1|path2|...|pathN|
 // |addr0  |addr1|addr2|...|addrN| (*addr0[0]=0; *addr0[1]=N)
 // _______________________________
 //
 // The structures of CPolytree64 and CPolytreeD are defined
-// below and they don't need to be repeated or explained here.
+// below and these structures don't need to be explained here.
-//
-// Finally, the pointer structures created and exported through
-// these functions can't safely be destroyed externally, so
-// a number of 'dispose functions are also exported.
 
 #ifndef CLIPPER2_EXPORT_H
 #define CLIPPER2_EXPORT_H
@@ -62,7 +58,7 @@ typedef struct CPolyPath64 {
   uint32_t      is_hole;
   uint32_t      child_count;
   CPolyPath64*  childs;
-} 
+}
 CPolyTree64;
 
 typedef struct CPolyPathD {
@@ -70,7 +66,7 @@ typedef struct CPolyPathD {
   uint32_t      is_hole;
   uint32_t      child_count;
   CPolyPathD*   childs;
-} 
+}
 CPolyTreeD;
 
 template <typename T>
@@ -101,6 +97,80 @@ inline Rect<T> CRectToRect(const CRect<T>& rect)
   return result;
 }
 
+#define EXTERN_DLL_EXPORT extern "C" __declspec(dllexport)
+
+//////////////////////////////////////////////////////
+// EXPORTED FUNCTION DEFINITIONS
+//////////////////////////////////////////////////////
+
+EXTERN_DLL_EXPORT const char* Version();
+
+// Some of the functions below will return data in the various CPath
+// and CPolyTree structures which are pointers to heap allocated
+// memory. Eventually this memory will need to be released with one
+// of the following 'DisposeExported' functions.  (This may be the
+// only safe way to release this memory since the executable
+// accessing these exported functions may use a memory manager that
+// allocates and releases heap memory in a different way. Also,
+// CPath structures that have been constructed by the executable
+// should not be destroyed using these 'DisposeExported' functions.)
+EXTERN_DLL_EXPORT void DisposeExportedCPath64(CPath64 p);
+EXTERN_DLL_EXPORT void DisposeExportedCPaths64(CPaths64& pp);
+EXTERN_DLL_EXPORT void DisposeExportedCPathD(CPathD p);
+EXTERN_DLL_EXPORT void DisposeExportedCPathsD(CPathsD& pp);
+EXTERN_DLL_EXPORT void DisposeExportedCPolyTree64(CPolyTree64*& cpt);
+EXTERN_DLL_EXPORT void DisposeExportedCPolyTreeD(CPolyTreeD*& cpt);
+
+// Boolean clipping:
+// cliptype: None=0, Intersection=1, Union=2, Difference=3, Xor=4
+// fillrule: EvenOdd=0, NonZero=1, Positive=2, Negative=3
+EXTERN_DLL_EXPORT int BooleanOp64(uint8_t cliptype,
+  uint8_t fillrule, const CPaths64 subjects,
+  const CPaths64 subjects_open, const CPaths64 clips,
+  CPaths64& solution, CPaths64& solution_open,
+  bool preserve_collinear = true, bool reverse_solution = false);
+EXTERN_DLL_EXPORT int BooleanOpPt64(uint8_t cliptype,
+  uint8_t fillrule, const CPaths64 subjects,
+  const CPaths64 subjects_open, const CPaths64 clips,
+  CPolyTree64*& solution, CPaths64& solution_open,
+  bool preserve_collinear = true, bool reverse_solution = false);
+EXTERN_DLL_EXPORT int BooleanOpD(uint8_t cliptype,
+  uint8_t fillrule, const CPathsD subjects,
+  const CPathsD subjects_open, const CPathsD clips,
+  CPathsD& solution, CPathsD& solution_open, int precision = 2,
+  bool preserve_collinear = true, bool reverse_solution = false);
+EXTERN_DLL_EXPORT int BooleanOpPtD(uint8_t cliptype,
+  uint8_t fillrule, const CPathsD subjects,
+  const CPathsD subjects_open, const CPathsD clips,
+  CPolyTreeD*& solution, CPathsD& solution_open, int precision = 2,
+  bool preserve_collinear = true, bool reverse_solution = false);
+
+// Polygon offsetting (inflate/deflate):
+// jointype: Square=0, Round=1, Miter=2
+// endtype: Polygon=0, Joined=1, Butt=2, Square=3, Round=4
+EXTERN_DLL_EXPORT CPaths64 InflatePaths64(const CPaths64 paths,
+  double delta, uint8_t jointype, uint8_t endtype, 
+  double miter_limit = 2.0, double arc_tolerance = 0.0, 
+  bool reverse_solution = false);
+EXTERN_DLL_EXPORT CPathsD InflatePathsD(const CPathsD paths,
+  double delta, uint8_t jointype, uint8_t endtype,
+  int precision = 2, double miter_limit = 2.0,
+  double arc_tolerance = 0.0, bool reverse_solution = false);
+
+// RectClip & RectClipLines:
+EXTERN_DLL_EXPORT CPaths64 RectClip64(const CRect64& rect,
+  const CPaths64 paths, bool convex_only = false);
+EXTERN_DLL_EXPORT CPathsD RectClipD(const CRectD& rect,
+  const CPathsD paths, int precision = 2, bool convex_only = false);
+EXTERN_DLL_EXPORT CPaths64 RectClipLines64(const CRect64& rect,
+  const CPaths64 paths);
+EXTERN_DLL_EXPORT CPathsD RectClipLinesD(const CRectD& rect,
+  const CPathsD paths, int precision = 2);
+
+//////////////////////////////////////////////////////
+// INTERNAL FUNCTIONS
+//////////////////////////////////////////////////////
+
 inline CPath64 CreateCPath64(size_t cnt1, size_t cnt2);
 inline CPath64 CreateCPath64(const Path64& p);
 inline CPaths64 CreateCPaths64(const Paths64& pp);
@@ -114,17 +184,14 @@ inline PathD ConvertCPathD(const CPathD& p);
 inline PathsD ConvertCPathsD(const CPathsD& pp);
 
 // the following function avoid multiple conversions
-inline Path64 ConvertCPathD(const CPathD& p, double scale);
-inline Paths64 ConvertCPathsD(const CPathsD& pp, double scale);
 inline CPathD CreateCPathD(const Path64& p, double scale);
 inline CPathsD CreateCPathsD(const Paths64& pp, double scale);
+inline Path64 ConvertCPathD(const CPathD& p, double scale);
+inline Paths64 ConvertCPathsD(const CPathsD& pp, double scale);
 
 inline CPolyTree64* CreateCPolyTree64(const PolyTree64& pt);
 inline CPolyTreeD* CreateCPolyTreeD(const PolyTree64& pt, double scale);
 
-#define EXTERN_DLL_EXPORT extern "C" __declspec(dllexport)
-
-
 EXTERN_DLL_EXPORT const char* Version()
 {
   return CLIPPER2_VERSION;
@@ -168,7 +235,7 @@ EXTERN_DLL_EXPORT int BooleanOp64(uint8_t cliptype,
   uint8_t fillrule, const CPaths64 subjects,
   const CPaths64 subjects_open, const CPaths64 clips,
   CPaths64& solution, CPaths64& solution_open,
-  bool preserve_collinear = true, bool reverse_solution = false)
+  bool preserve_collinear, bool reverse_solution)
 {
   if (cliptype > static_cast<uint8_t>(ClipType::Xor)) return -4;
   if (fillrule > static_cast<uint8_t>(FillRule::Negative)) return -3;
@@ -195,7 +262,7 @@ EXTERN_DLL_EXPORT int BooleanOpPt64(uint8_t cliptype,
   uint8_t fillrule, const CPaths64 subjects,
   const CPaths64 subjects_open, const CPaths64 clips,
   CPolyTree64*& solution, CPaths64& solution_open,
-  bool preserve_collinear = true, bool reverse_solution = false)
+  bool preserve_collinear, bool reverse_solution)
 {
   if (cliptype > static_cast<uint8_t>(ClipType::Xor)) return -4;
   if (fillrule > static_cast<uint8_t>(FillRule::Negative)) return -3;
@@ -222,8 +289,8 @@ EXTERN_DLL_EXPORT int BooleanOpPt64(uint8_t cliptype,
 EXTERN_DLL_EXPORT int BooleanOpD(uint8_t cliptype,
   uint8_t fillrule, const CPathsD subjects,
   const CPathsD subjects_open, const CPathsD clips,
-  CPathsD& solution, CPathsD& solution_open, int precision = 2,
+  CPathsD& solution, CPathsD& solution_open, int precision,
-  bool preserve_collinear = true, bool reverse_solution = false)
+  bool preserve_collinear, bool reverse_solution)
 {
   if (precision < -8 || precision > 8) return -5;
   if (cliptype > static_cast<uint8_t>(ClipType::Xor)) return -4;
@@ -254,8 +321,8 @@ EXTERN_DLL_EXPORT int BooleanOpD(uint8_t cliptype,
 EXTERN_DLL_EXPORT int BooleanOpPtD(uint8_t cliptype,
   uint8_t fillrule, const CPathsD subjects,
   const CPathsD subjects_open, const CPathsD clips,
-  CPolyTreeD*& solution, CPathsD& solution_open, int precision = 2,
+  CPolyTreeD*& solution, CPathsD& solution_open, int precision,
-  bool preserve_collinear = true, bool reverse_solution = false)
+  bool preserve_collinear, bool reverse_solution)
 {
   if (precision < -8 || precision > 8) return -5;
   if (cliptype > static_cast<uint8_t>(ClipType::Xor)) return -4;
@@ -285,84 +352,58 @@ EXTERN_DLL_EXPORT int BooleanOpPtD(uint8_t cliptype,
 }
 
 EXTERN_DLL_EXPORT CPaths64 InflatePaths64(const CPaths64 paths,
-  double delta, uint8_t jt, uint8_t et, double miter_limit = 2.0,
+  double delta, uint8_t jointype, uint8_t endtype, double miter_limit,
-  double arc_tolerance = 0.0, bool reverse_solution = false)
+  double arc_tolerance, bool reverse_solution)
 {
   Paths64 pp;
   pp = ConvertCPaths64(paths);
 
   ClipperOffset clip_offset( miter_limit, 
     arc_tolerance, reverse_solution);
-  clip_offset.AddPaths(pp, JoinType(jt), EndType(et));
+  clip_offset.AddPaths(pp, JoinType(jointype), EndType(endtype));
-  Paths64 result = clip_offset.Execute(delta);
+  Paths64 result; 
+  clip_offset.Execute(delta, result);
   return CreateCPaths64(result);
 }
 
 EXTERN_DLL_EXPORT CPathsD InflatePathsD(const CPathsD paths,
-  double delta, uint8_t jt, uint8_t et,
+  double delta, uint8_t jointype, uint8_t endtype,
-  double precision = 2, double miter_limit = 2.0,
+  int precision, double miter_limit,
-  double arc_tolerance = 0.0, bool reverse_solution = false)
+  double arc_tolerance, bool reverse_solution)
 {
   if (precision < -8 || precision > 8 || !paths) return nullptr;
   const double scale = std::pow(10, precision);
   ClipperOffset clip_offset(miter_limit, arc_tolerance, reverse_solution);
   Paths64 pp = ConvertCPathsD(paths, scale);
-  clip_offset.AddPaths(pp, JoinType(jt), EndType(et));
+  clip_offset.AddPaths(pp, JoinType(jointype), EndType(endtype));
-  Paths64 result = clip_offset.Execute(delta * scale);
+  Paths64 result;
+  clip_offset.Execute(delta * scale, result);
   return CreateCPathsD(result, 1/scale);
 }
 
 EXTERN_DLL_EXPORT CPaths64 RectClip64(const CRect64& rect,
-  const CPaths64 paths)
+  const CPaths64 paths, bool convex_only)
 {
-  log(rect.left);
-  log(rect.right);
   if (CRectIsEmpty(rect) || !paths) return nullptr;
   Rect64 r64 = CRectToRect(rect);
   class RectClip rc(r64);
   Paths64 pp = ConvertCPaths64(paths);
-  Paths64 result;
+  Paths64 result = rc.Execute(pp, convex_only);
-  result.reserve(pp.size());
-  for (const Path64& p : pp)
-  {
-    Rect64 pathRec = Bounds(p);
-    if (!r64.Intersects(pathRec)) continue;
-    
-    if (r64.Contains(pathRec))
-      result.push_back(p);
-    else
-    {
-      Path64 p2 = rc.Execute(p);
-      if (!p2.empty()) result.push_back(std::move(p2));
-    }
-  }
   return CreateCPaths64(result);
 }
 
 EXTERN_DLL_EXPORT CPathsD RectClipD(const CRectD& rect,
-  const CPathsD paths, int precision = 2)
+  const CPathsD paths, int precision, bool convex_only)
 {
   if (CRectIsEmpty(rect) || !paths) return nullptr;
   if (precision < -8 || precision > 8) return nullptr;
   const double scale = std::pow(10, precision);
-  Rect64 r = ScaleRect<int64_t, double>(CRectToRect(rect), scale);
+
+  RectD r = CRectToRect(rect);
+  Rect64 rec = ScaleRect<int64_t, double>(r, scale);
   Paths64 pp = ConvertCPathsD(paths, scale);
-  class RectClip rc(r);
+  class RectClip rc(rec);
-  Paths64 result;
+  Paths64 result = rc.Execute(pp, convex_only);
-  result.reserve(pp.size());
-  for (const Path64& p : pp)
-  {
-    Rect64 pathRec = Bounds(p);
-    if (!r.Intersects(pathRec)) continue;
-    
-    if (r.Contains(pathRec))
-      result.push_back(p);
-    else
-    {
-      Path64 p2 = rc.Execute(p);
-      if (!p2.empty()) result.push_back(std::move(p2));
-    }
-  }
   return CreateCPathsD(result, 1/scale);
 }
 
@@ -373,58 +414,27 @@ EXTERN_DLL_EXPORT CPaths64 RectClipLines64(const CRect64& rect,
   Rect64 r = CRectToRect(rect);
   class RectClipLines rcl (r);
   Paths64 pp = ConvertCPaths64(paths);
-  Paths64 result;
+  Paths64 result = rcl.Execute(pp);
-  result.reserve(pp.size());
-
-  for (const Path64& p : pp)
-  {
-    Rect64 pathRec = Bounds(p);
-    if (!r.Intersects(pathRec)) continue;
-    
-    if (r.Contains(pathRec))
-      result.push_back(p);
-    else
-    {
-      Paths64 pp2 = rcl.Execute(p);
-      if (!pp2.empty())
-        result.insert(result.end(), pp2.begin(), pp2.end());
-    }
-  }
   return CreateCPaths64(result);
 }
 
 EXTERN_DLL_EXPORT CPathsD RectClipLinesD(const CRectD& rect, 
-  const CPathsD paths, int precision = 2)
+  const CPathsD paths, int precision)
 {
-  Paths64 result;
   if (CRectIsEmpty(rect) || !paths) return nullptr;
   if (precision < -8 || precision > 8) return nullptr;
   const double scale = std::pow(10, precision);
   Rect64 r = ScaleRect<int64_t, double>(CRectToRect(rect), scale);
   class RectClipLines rcl(r);
   Paths64 pp = ConvertCPathsD(paths, scale);
-
+  Paths64 result = rcl.Execute(pp);
-  result.reserve(pp.size());
-  for (const Path64& p : pp)
-  {
-    Rect64 pathRec = Bounds(p);
-    if (!r.Intersects(pathRec)) continue;
-    
-    if (r.Contains(pathRec))
-      result.push_back(p);
-    else
-    {
-      Paths64 pp2 = rcl.Execute(p);
-      if (pp2.empty()) continue;
-      result.insert(result.end(), pp2.begin(), pp2.end());
-    }
-  }
   return CreateCPathsD(result, 1/scale);
 }
 
 inline CPath64 CreateCPath64(size_t cnt1, size_t cnt2)
 {
-  // create a dummy counter path 
+  // allocates memory for CPath64, fills in the counter, and
+  // returns the structure ready to be filled with path data
   CPath64 result = new int64_t[2 + cnt1 *2];
   result[0] = cnt1;
   result[1] = cnt2;
@@ -433,6 +443,8 @@ inline CPath64 CreateCPath64(size_t cnt1, size_t cnt2)
 
 inline CPath64 CreateCPath64(const Path64& p)
 {
+  // allocates memory for CPath64, fills the counter
+  // and returns the memory filled with path data
   size_t cnt = p.size();
   if (!cnt) return nullptr;
   CPath64 result = CreateCPath64(cnt, 0);
@@ -469,6 +481,8 @@ inline Path64 ConvertCPath64(const CPath64& p)
 
 inline CPaths64 CreateCPaths64(const Paths64& pp)
 {
+  // allocates memory for multiple CPath64 and
+  // and returns this memory filled with path data
   size_t cnt = pp.size(), cnt2 = cnt;
 
   // don't allocate space for empty paths
@@ -505,7 +519,8 @@ inline Paths64 ConvertCPaths64(const CPaths64& pp)
 
 inline CPathD CreateCPathD(size_t cnt1, size_t cnt2)
 {
-  // create a dummy path counter
+  // allocates memory for CPathD, fills in the counter, and
+  // returns the structure ready to be filled with path data
   CPathD result = new double[2 + cnt1 * 2];
   result[0] = static_cast<double>(cnt1);
   result[1] = static_cast<double>(cnt2);
@@ -514,6 +529,8 @@ inline CPathD CreateCPathD(size_t cnt1, size_t cnt2)
 
 inline CPathD CreateCPathD(const PathD& p)
 {
+  // allocates memory for CPath, fills the counter
+  // and returns the memory fills with path data
   size_t cnt = p.size();
   if (!cnt) return nullptr; 
   CPathD result = CreateCPathD(cnt, 0);
@@ -621,6 +638,8 @@ inline Paths64 ConvertCPathsD(const CPathsD& pp, double scale)
 
 inline CPathD CreateCPathD(const Path64& p, double scale)
 {
+  // allocates memory for CPathD, fills in the counter, and
+  // returns the structure filled with *scaled* path data
   size_t cnt = p.size();
   if (!cnt) return nullptr;
   CPathD result = CreateCPathD(cnt, 0);
@@ -636,6 +655,8 @@ inline CPathD CreateCPathD(const Path64& p, double scale)
 
 inline CPathsD CreateCPathsD(const Paths64& pp, double scale)
 {
+  // allocates memory for *multiple* CPathD, and
+  // returns the structure filled with scaled path data
   size_t cnt = pp.size(), cnt2 = cnt;
   // don't allocate space for empty paths
   for (size_t i = 0; i < cnt; ++i)
@@ -653,17 +674,17 @@ inline CPathsD CreateCPathsD(const Paths64& pp, double scale)
 }
 
 inline void InitCPolyPath64(CPolyTree64* cpt, 
-  bool is_hole, const PolyPath64* pp)
+  bool is_hole, const std::unique_ptr <PolyPath64>& pp)
 {
   cpt->polygon = CreateCPath64(pp->Polygon());
   cpt->is_hole = is_hole;
   size_t child_cnt = pp->Count();
-  cpt->child_count = child_cnt;
+  cpt->child_count = static_cast<uint32_t>(child_cnt);
   cpt->childs = nullptr;
   if (!child_cnt) return;
   cpt->childs = new CPolyPath64[child_cnt];
   CPolyPath64* child = cpt->childs;
-  for (const PolyPath64* pp_child : *pp)
+  for (const std::unique_ptr <PolyPath64>& pp_child : *pp)
     InitCPolyPath64(child++, !is_hole, pp_child);  
 }
 
@@ -674,11 +695,11 @@ inline CPolyTree64* CreateCPolyTree64(const PolyTree64& pt)
   result->is_hole = false;
   size_t child_cnt = pt.Count();
   result->childs = nullptr;
-  result->child_count = child_cnt;
+  result->child_count = static_cast<uint32_t>(child_cnt);
   if (!child_cnt) return result;
   result->childs = new CPolyPath64[child_cnt];
   CPolyPath64* child = result->childs;
-  for (const PolyPath64* pp : pt)
+  for (const std::unique_ptr <PolyPath64>& pp : pt)
     InitCPolyPath64(child++, true, pp);
   return result;
 }
@@ -701,17 +722,17 @@ EXTERN_DLL_EXPORT void DisposeExportedCPolyTree64(CPolyTree64*& cpt)
 }
 
 inline void InitCPolyPathD(CPolyTreeD* cpt,
-  bool is_hole, const PolyPath64* pp, double scale)
+  bool is_hole, const std::unique_ptr <PolyPath64>& pp, double scale)
 {
   cpt->polygon = CreateCPathD(pp->Polygon(), scale);
   cpt->is_hole = is_hole;
   size_t child_cnt = pp->Count();
-  cpt->child_count = child_cnt;
+  cpt->child_count = static_cast<uint32_t>(child_cnt);
   cpt->childs = nullptr;
   if (!child_cnt) return;
   cpt->childs = new CPolyPathD[child_cnt];
   CPolyPathD* child = cpt->childs;
-  for (const PolyPath64* pp_child : *pp)
+  for (const std::unique_ptr <PolyPath64>& pp_child : *pp)
     InitCPolyPathD(child++, !is_hole, pp_child, scale);
 }
 
@@ -726,7 +747,7 @@ inline CPolyTreeD* CreateCPolyTreeD(const PolyTree64& pt, double scale)
   if (!child_cnt) return result;
   result->childs = new CPolyPathD[child_cnt];
   CPolyPathD* child = result->childs;
-  for (const PolyPath64* pp : pt)
+  for (const std::unique_ptr <PolyPath64>& pp : pt)
     InitCPolyPathD(child++, true, pp, scale);
   return result;
 }

thirdparty/clipper2/Clipper2Lib/include/clipper2/clipper.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  26 October 2022                                                 *
+* Date      :  9 February 2023                                                 *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  This module provides a simple interface to the Clipper Library  *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -11,6 +11,7 @@
 #define CLIPPER_H
 
 #include <cstdlib>
+#include <type_traits>
 #include <vector>
 
 #include "clipper.core.h"
@@ -21,21 +22,6 @@
 
 namespace Clipper2Lib {
 
-  static const char* precision_error = 
-    "Precision exceeds the permitted range";
-
-  static const Rect64 MaxInvalidRect64 = Rect64(
-    (std::numeric_limits<int64_t>::max)(),
-    (std::numeric_limits<int64_t>::max)(),
-    (std::numeric_limits<int64_t>::lowest)(),
-    (std::numeric_limits<int64_t>::lowest)());
-
-  static const RectD MaxInvalidRectD = RectD(
-      (std::numeric_limits<double>::max)(),
-      (std::numeric_limits<double>::max)(),
-      (std::numeric_limits<double>::lowest)(),
-      (std::numeric_limits<double>::lowest)());
-
   inline Paths64 BooleanOp(ClipType cliptype, FillRule fillrule,
     const Paths64& subjects, const Paths64& clips)
   {    
@@ -58,12 +44,13 @@ namespace Clipper2Lib {
   }
 
   inline PathsD BooleanOp(ClipType cliptype, FillRule fillrule,
-    const PathsD& subjects, const PathsD& clips, int decimal_prec = 2)
+    const PathsD& subjects, const PathsD& clips, int precision = 2)
   {
-    if (decimal_prec > 8 || decimal_prec < -8)
+    int error_code = 0;
-      throw Clipper2Exception(precision_error);
+    CheckPrecision(precision, error_code);
     PathsD result;
-    ClipperD clipper(decimal_prec);
+    if (error_code) return result;
+    ClipperD clipper(precision);
     clipper.AddSubject(subjects);
     clipper.AddClip(clips);
     clipper.Execute(cliptype, fillrule, result);
@@ -72,12 +59,13 @@ namespace Clipper2Lib {
 
   inline void BooleanOp(ClipType cliptype, FillRule fillrule,
     const PathsD& subjects, const PathsD& clips, 
-    PolyTreeD& polytree, int decimal_prec = 2)
+    PolyTreeD& polytree, int precision = 2)
   {
-    if (decimal_prec > 8 || decimal_prec < -8)
+    polytree.Clear();
-      throw Clipper2Exception(precision_error);
+    int error_code = 0;
-    PathsD result;
+    CheckPrecision(precision, error_code);
-    ClipperD clipper(decimal_prec);
+    if (error_code) return;
+    ClipperD clipper(precision);
     clipper.AddSubject(subjects);
     clipper.AddClip(clips);
     clipper.Execute(cliptype, fillrule, polytree);
@@ -112,12 +100,13 @@ namespace Clipper2Lib {
     return result;
   }
 
-  inline PathsD Union(const PathsD& subjects, FillRule fillrule, int decimal_prec = 2)
+  inline PathsD Union(const PathsD& subjects, FillRule fillrule, int precision = 2)
   {
-    if (decimal_prec > 8 || decimal_prec < -8)
-      throw Clipper2Exception(precision_error);
     PathsD result;
-    ClipperD clipper(decimal_prec);
+    int error_code = 0;
+    CheckPrecision(precision, error_code);
+    if (error_code) return result;
+    ClipperD clipper(precision);
     clipper.AddSubject(subjects);
     clipper.Execute(ClipType::Union, fillrule, result);
     return result;
@@ -144,31 +133,40 @@ namespace Clipper2Lib {
   }
 
   inline Paths64 InflatePaths(const Paths64& paths, double delta,
-    JoinType jt, EndType et, double miter_limit = 2.0)
+    JoinType jt, EndType et, double miter_limit = 2.0,
+    double arc_tolerance = 0.0)
   {
-    ClipperOffset clip_offset(miter_limit);
+    if (!delta) return paths;
+    ClipperOffset clip_offset(miter_limit, arc_tolerance);
     clip_offset.AddPaths(paths, jt, et);
-    return clip_offset.Execute(delta);
+    Paths64 solution;
+    clip_offset.Execute(delta, solution);
+    return solution;
   }
 
   inline PathsD InflatePaths(const PathsD& paths, double delta,
-    JoinType jt, EndType et, double miter_limit = 2.0, double precision = 2)
+    JoinType jt, EndType et, double miter_limit = 2.0, 
+    int precision = 2, double arc_tolerance = 0.0)
   {
-    if (precision < -8 || precision > 8)
+    int error_code = 0;
-      throw Clipper2Exception(precision_error);
+    CheckPrecision(precision, error_code);
+    if (!delta) return paths;
+    if (error_code) return PathsD();
     const double scale = std::pow(10, precision);
-    ClipperOffset clip_offset(miter_limit);
+    ClipperOffset clip_offset(miter_limit, arc_tolerance);
-    clip_offset.AddPaths(ScalePaths<int64_t,double>(paths, scale), jt, et);
+    clip_offset.AddPaths(ScalePaths<int64_t,double>(paths, scale, error_code), jt, et);
-    Paths64 tmp = clip_offset.Execute(delta * scale);
+    if (error_code) return PathsD();
-    return ScalePaths<double, int64_t>(tmp, 1 / scale);
+    Paths64 solution;
+    clip_offset.Execute(delta * scale, solution);
+    return ScalePaths<double, int64_t>(solution, 1 / scale, error_code);
   }
 
   inline Path64 TranslatePath(const Path64& path, int64_t dx, int64_t dy)
   {
     Path64 result;
     result.reserve(path.size());
-    for (const Point64& pt : path)
+    std::transform(path.begin(), path.end(), back_inserter(result),
-      result.push_back(Point64(pt.x + dx, pt.y + dy));
+      [dx, dy](const auto& pt) { return Point64(pt.x + dx, pt.y +dy); });
     return result;
   }
 
@@ -176,8 +174,8 @@ namespace Clipper2Lib {
   {
     PathD result;
     result.reserve(path.size());
-    for (const PointD& pt : path)
+    std::transform(path.begin(), path.end(), back_inserter(result),
-      result.push_back(PointD(pt.x + dx, pt.y + dy));
+      [dx, dy](const auto& pt) { return PointD(pt.x + dx, pt.y + dy); });
     return result;
   }
 
@@ -185,8 +183,8 @@ namespace Clipper2Lib {
   {
     Paths64 result;
     result.reserve(paths.size());
-    for (const Path64& path : paths)
+    std::transform(paths.begin(), paths.end(), back_inserter(result),
-      result.push_back(TranslatePath(path, dx, dy));
+      [dx, dy](const auto& path) { return TranslatePath(path, dx, dy); });
     return result;
   }
 
@@ -194,220 +192,79 @@ namespace Clipper2Lib {
   {
     PathsD result;
     result.reserve(paths.size());
-    for (const PathD& path : paths)
+    std::transform(paths.begin(), paths.end(), back_inserter(result),
-      result.push_back(TranslatePath(path, dx, dy));
+      [dx, dy](const auto& path) { return TranslatePath(path, dx, dy); });
     return result;
   }
 
-  inline Rect64 Bounds(const Path64& path)
+  inline Paths64 RectClip(const Rect64& rect, 
-  {
+    const Paths64& paths, bool convex_only = false)
-    Rect64 rec = MaxInvalidRect64;
-    for (const Point64& pt : path)
-    {
-      if (pt.x < rec.left) rec.left = pt.x;
-      if (pt.x > rec.right) rec.right = pt.x;
-      if (pt.y < rec.top) rec.top = pt.y;
-      if (pt.y > rec.bottom) rec.bottom = pt.y;
-    }
-    if (rec.IsEmpty()) return Rect64();
-    return rec;
-  }
-  
-  inline Rect64 Bounds(const Paths64& paths)
-  {
-    Rect64 rec = MaxInvalidRect64;
-    for (const Path64& path : paths)
-      for (const Point64& pt : path)
-      {
-        if (pt.x < rec.left) rec.left = pt.x;
-        if (pt.x > rec.right) rec.right = pt.x;
-        if (pt.y < rec.top) rec.top = pt.y;
-        if (pt.y > rec.bottom) rec.bottom = pt.y;
-      }
-    if (rec.IsEmpty()) return Rect64();
-    return rec;
-  }
-
-  inline RectD Bounds(const PathD& path)
-  {
-    RectD rec = MaxInvalidRectD;
-    for (const PointD& pt : path)
-    {
-      if (pt.x < rec.left) rec.left = pt.x;
-      if (pt.x > rec.right) rec.right = pt.x;
-      if (pt.y < rec.top) rec.top = pt.y;
-      if (pt.y > rec.bottom) rec.bottom = pt.y;
-    }
-    if (rec.IsEmpty()) return RectD();
-    return rec;
-  }
-
-  inline RectD Bounds(const PathsD& paths)
-  {
-    RectD rec = MaxInvalidRectD;
-    for (const PathD& path : paths)
-      for (const PointD& pt : path)
-      {
-        if (pt.x < rec.left) rec.left = pt.x;
-        if (pt.x > rec.right) rec.right = pt.x;
-        if (pt.y < rec.top) rec.top = pt.y;
-        if (pt.y > rec.bottom) rec.bottom = pt.y;
-      }
-    if (rec.IsEmpty()) return RectD();
-    return rec;
-  }
-
-  inline Path64 ClipRect(const Rect64& rect, const Path64& path)
-  {
-    if (rect.IsEmpty() || path.empty()) return Path64();
-    Rect64 pathRec = Bounds(path);
-    if (!rect.Intersects(pathRec)) return Path64();
-    if (rect.Contains(pathRec)) return path;
-    class RectClip rc(rect);
-    return rc.Execute(path);
-  }
-  
-  inline Paths64 ClipRect(const Rect64& rect, const Paths64& paths)
   {
     if (rect.IsEmpty() || paths.empty()) return Paths64();
     class RectClip rc(rect);
-    Paths64 result;
+    return rc.Execute(paths, convex_only);
-    result.reserve(paths.size());
-
-    for (const Path64& p : paths)
-    {
-      Rect64 pathRec = Bounds(p);
-      if (!rect.Intersects(pathRec)) 
-        continue;
-      else if (rect.Contains(pathRec))
-        result.push_back(p);
-      else
-      {
-        Path64 p2 = rc.Execute(p);
-        if (!p2.empty()) result.push_back(std::move(p2));
-      }
-    }
-    return result;
   }
 
-  inline PathD ClipRect(const RectD& rect, const PathD& path, int precision = 2)
+  inline Paths64 RectClip(const Rect64& rect, 
+    const Path64& path, bool convex_only = false)
   {
-    if (rect.IsEmpty() || path.empty() ||
+    if (rect.IsEmpty() || path.empty()) return Paths64();
-      !rect.Contains(Bounds(path))) return PathD();
+    class RectClip rc(rect);
-    if (precision < -8 || precision > 8)
+    return rc.Execute(Paths64{ path }, convex_only);
-      throw Clipper2Exception(precision_error);
-    const double scale = std::pow(10, precision);
-    Rect64 r = ScaleRect<int64_t, double>(rect, scale);
-    class RectClip rc(r);
-    Path64 p = ScalePath<int64_t, double>(path, scale);
-    return ScalePath<double, int64_t>(rc.Execute(p), 1 / scale);
   }
 
-  inline PathsD ClipRect(const RectD& rect, const PathsD& paths, int precision = 2)
+  inline PathsD RectClip(const RectD& rect, 
+    const PathsD& paths, bool convex_only = false, int precision = 2)
   {
     if (rect.IsEmpty() || paths.empty()) return PathsD();
-    if (precision < -8 || precision > 8)
+    int error_code = 0;
-      throw Clipper2Exception(precision_error);
+    CheckPrecision(precision, error_code);
+    if (error_code) return PathsD();
     const double scale = std::pow(10, precision);
     Rect64 r = ScaleRect<int64_t, double>(rect, scale);
     class RectClip rc(r);
-    PathsD result;
+    Paths64 pp = ScalePaths<int64_t, double>(paths, scale, error_code);
-    result.reserve(paths.size());
+    if (error_code) return PathsD(); // ie: error_code result is lost 
-    for (const PathD& path : paths) 
+    return ScalePaths<double, int64_t>(
-    {
+      rc.Execute(pp, convex_only), 1 / scale, error_code);
-      RectD pathRec = Bounds(path);
-      if (!rect.Intersects(pathRec))
-        continue;
-      else if (rect.Contains(pathRec))
-        result.push_back(path);
-      else
-      {
-        Path64 p = ScalePath<int64_t, double>(path, scale);
-        p = rc.Execute(p);
-        if (!p.empty()) 
-          result.push_back(ScalePath<double, int64_t>(p, 1 / scale));
-      }
-    }
-    return result;
   }
 
-  inline Paths64 ClipLinesRect(const Rect64& rect, const Path64& path)
+  inline PathsD RectClip(const RectD& rect, 
+    const PathD& path, bool convex_only = false, int precision = 2)
   {
-    Paths64 result;
+    return RectClip(rect, PathsD{ path }, convex_only, precision);
-    if (rect.IsEmpty() || path.empty()) return result;
+  }
-    Rect64 pathRec = Bounds(path);
+
-    if (!rect.Intersects(pathRec)) return result;
+  inline Paths64 RectClipLines(const Rect64& rect, const Paths64& lines)
-    if (rect.Contains(pathRec)) 
+  {
-    {
+    if (rect.IsEmpty() || lines.empty()) return Paths64();
-      result.push_back(path);
-      return result;
-    }
     class RectClipLines rcl(rect);
-    return rcl.Execute(path);
+    return rcl.Execute(lines);
   }
 
-  inline Paths64 ClipLinesRect(const Rect64& rect, const Paths64& paths)
+  inline Paths64 RectClipLines(const Rect64& rect, const Path64& line)
   {
-    Paths64 result;
+    return RectClipLines(rect, Paths64{ line });
-    if (rect.IsEmpty() || paths.empty()) return result;
-    class RectClipLines rcl(rect);
-    for (const Path64& p : paths)
-    {
-      Rect64 pathRec = Bounds(p);
-      if (!rect.Intersects(pathRec))
-        continue;
-      else if (rect.Contains(pathRec))
-        result.push_back(p);
-      else
-      {
-        Paths64 pp = rcl.Execute(p);
-        if (!pp.empty()) 
-          result.insert(result.end(), pp.begin(), pp.end());
-      }
-    }
-    return result;
   }
 
-  inline PathsD ClipLinesRect(const RectD& rect, const PathD& path, int precision = 2)
+  inline PathsD RectClipLines(const RectD& rect, const PathD& line, int precision = 2)
   {
-    if (rect.IsEmpty() || path.empty() ||
+    return RectClip(rect, PathsD{ line }, precision);
-      !rect.Contains(Bounds(path))) return PathsD();
+  }
-    if (precision < -8 || precision > 8)
+
-      throw Clipper2Exception(precision_error);
+  inline PathsD RectClipLines(const RectD& rect, const PathsD& lines, int precision = 2)
+  {
+    if (rect.IsEmpty() || lines.empty()) return PathsD();
+    int error_code = 0;
+    CheckPrecision(precision, error_code);
+    if (error_code) return PathsD();
     const double scale = std::pow(10, precision);
     Rect64 r = ScaleRect<int64_t, double>(rect, scale);
     class RectClipLines rcl(r);
-    Path64 p = ScalePath<int64_t, double>(path, scale);
+    Paths64 p = ScalePaths<int64_t, double>(lines, scale, error_code);
-    return ScalePaths<double, int64_t>(rcl.Execute(p), 1 / scale);
+    if (error_code) return PathsD();
-  }
+    p = rcl.Execute(p);
-
+    return ScalePaths<double, int64_t>(p, 1 / scale, error_code);
-  inline PathsD ClipLinesRect(const RectD& rect, const PathsD& paths, int precision = 2)
-  {
-    PathsD result;
-    if (rect.IsEmpty() || paths.empty()) return result;
-    if (precision < -8 || precision > 8)
-      throw Clipper2Exception(precision_error);
-    const double scale = std::pow(10, precision);
-    Rect64 r = ScaleRect<int64_t, double>(rect, scale);
-    class RectClipLines rcl(r);
-    result.reserve(paths.size());
-    for (const PathD& path : paths)
-    {
-      RectD pathRec = Bounds(path);
-      if (!rect.Intersects(pathRec))
-        continue;
-      else if (rect.Contains(pathRec))
-        result.push_back(path);
-      else
-      {
-        Path64 p = ScalePath<int64_t, double>(path, scale);
-        Paths64 pp = rcl.Execute(p);
-        if (pp.empty()) continue;
-        PathsD ppd = ScalePaths<double, int64_t>(pp, 1 / scale);
-        result.insert(result.end(), ppd.begin(), ppd.end());
-      }
-    }
-    return result;
   }
 
   namespace details
@@ -416,179 +273,219 @@ namespace Clipper2Lib {
     inline void PolyPathToPaths64(const PolyPath64& polypath, Paths64& paths)
     {
       paths.push_back(polypath.Polygon());
-      for (const PolyPath* child : polypath)
+      for (const auto& child : polypath)
-        PolyPathToPaths64(*(PolyPath64*)(child), paths);
+        PolyPathToPaths64(*child, paths);
     }
 
     inline void PolyPathToPathsD(const PolyPathD& polypath, PathsD& paths)
     {
       paths.push_back(polypath.Polygon());
-      for (const PolyPath* child : polypath)
+      for (const auto& child : polypath)
-        PolyPathToPathsD(*(PolyPathD*)(child), paths);
+        PolyPathToPathsD(*child, paths);
     }
 
     inline bool PolyPath64ContainsChildren(const PolyPath64& pp)
     {
-      for (auto ch : pp)
+      for (const auto& child : pp)
       {
-        PolyPath64* child = (PolyPath64*)ch;
+        // return false if this child isn't fully contained by its parent
+
+        // the following algorithm is a bit too crude, and doesn't account
+        // for rounding errors. A better algorithm is to return false when
+        // consecutive vertices are found outside the parent's polygon.
+
+        //const Path64& path = pp.Polygon();
+        //if (std::any_of(child->Polygon().cbegin(), child->Polygon().cend(),
+        //  [path](const auto& pt) {return (PointInPolygon(pt, path) ==
+        //    PointInPolygonResult::IsOutside); })) return false;
+
+        int outsideCnt = 0;
         for (const Point64& pt : child->Polygon())
-          if (PointInPolygon(pt, pp.Polygon()) == PointInPolygonResult::IsOutside)
+        {
-            return false;
+          PointInPolygonResult result = PointInPolygon(pt, pp.Polygon());
+          if (result == PointInPolygonResult::IsInside) --outsideCnt;
+          else if (result == PointInPolygonResult::IsOutside) ++outsideCnt;
+          if (outsideCnt > 1) return false;
+          else if (outsideCnt < -1) break;
+        }
+
+        // now check any nested children too
         if (child->Count() > 0 && !PolyPath64ContainsChildren(*child))
           return false;
       }
       return true;
     }
 
-    inline bool GetInt(std::string::const_iterator& iter, const
+    static void OutlinePolyPath(std::ostream& os, 
-      std::string::const_iterator& end_iter, int64_t& val)
+      bool isHole, size_t count, const std::string& preamble)
     {
-      val = 0;
+      std::string plural = (count == 1) ? "." : "s.";
-      bool is_neg = *iter == '-';
+      if (isHole)
-      if (is_neg) ++iter;
-      std::string::const_iterator start_iter = iter;
-      while (iter != end_iter &&
-        ((*iter >= '0') && (*iter <= '9')))
       {
-        val = val * 10 + (static_cast<int64_t>(*iter++) - '0');
+        if (count)
+          os << preamble << "+- Hole with " << count <<
+          " nested polygon" << plural << std::endl;
+        else
+          os << preamble << "+- Hole" << std::endl;
       }
-      if (is_neg) val = -val;
+      else
-      return (iter != start_iter);
-    }
-
-    inline bool GetFloat(std::string::const_iterator& iter, const 
-      std::string::const_iterator& end_iter, double& val)
-    {
-      val = 0;
-      bool is_neg = *iter == '-';
-      if (is_neg) ++iter;
-      int dec_pos = 1;
-      const std::string::const_iterator start_iter = iter;
-      while (iter != end_iter && (*iter == '.' ||
-        ((*iter >= '0') && (*iter <= '9'))))
       {
-        if (*iter == '.')
+        if (count)
-        {
+          os << preamble << "+- Polygon with " << count <<
-          if (dec_pos != 1) break;
+          " hole" << plural << std::endl;
-          dec_pos = 0;
+        else
-          ++iter;
+          os << preamble << "+- Polygon" << std::endl;
-          continue;
-        }
-        if (dec_pos != 1) --dec_pos;
-        val = val * 10 + ((int64_t)(*iter++) - '0');
-      }
-      if (iter == start_iter || dec_pos == 0) return false;
-      if (dec_pos < 0)
-        val *= std::pow(10, dec_pos);
-      if (is_neg)
-        val *= -1;
-      return true;
-    }
-
-    inline void SkipWhiteSpace(std::string::const_iterator& iter, 
-      const std::string::const_iterator& end_iter)
-    {
-      while (iter != end_iter && *iter <= ' ') ++iter;
-    }
-
-    inline void SkipSpacesWithOptionalComma(std::string::const_iterator& iter, 
-      const std::string::const_iterator& end_iter)
-    {
-      bool comma_seen = false;
-      while (iter != end_iter)
-      {
-        if (*iter == ' ') ++iter;
-        else if (*iter == ',')
-        {
-          if (comma_seen) return; // don't skip 2 commas!
-          comma_seen = true;
-          ++iter;
-        }
-        else return;                
       }
     }
 
-    inline bool has_one_match(const char c, char* chrs)
+    static void OutlinePolyPath64(std::ostream& os, const PolyPath64& pp,
+      std::string preamble, bool last_child)
     {
-      while (*chrs > 0 && c != *chrs) ++chrs;
+      OutlinePolyPath(os, pp.IsHole(), pp.Count(), preamble);
-      if (!*chrs) return false;
+      preamble += (!last_child) ? "|  " : "   ";
-      *chrs = ' '; // only match once per char
+      if (pp.Count())
-      return true;
+      {
+        PolyPath64List::const_iterator it = pp.begin();
+        for (; it < pp.end() - 1; ++it)
+          OutlinePolyPath64(os, **it, preamble, false);
+        OutlinePolyPath64(os, **it, preamble, true);
+      }
     }
 
-
+    static void OutlinePolyPathD(std::ostream& os, const PolyPathD& pp,
-    inline void SkipUserDefinedChars(std::string::const_iterator& iter,
+      std::string preamble, bool last_child)
-      const std::string::const_iterator& end_iter, const std::string& skip_chars)
     {
-      const size_t MAX_CHARS = 16;
+      OutlinePolyPath(os, pp.IsHole(), pp.Count(), preamble);
-      char buff[MAX_CHARS] = {0};
+      preamble += (!last_child) ? "|  " : "   ";
-      std::copy(skip_chars.cbegin(), skip_chars.cend(), &buff[0]);
+      if (pp.Count())
-      while (iter != end_iter && 
+      {
-        (*iter <= ' ' || has_one_match(*iter, buff))) ++iter;
+        PolyPathDList::const_iterator it = pp.begin();
-      return;
+        for (; it < pp.end() - 1; ++it)
+          OutlinePolyPathD(os, **it, preamble, false);
+        OutlinePolyPathD(os, **it, preamble, true);
+      }
     }
 
   } // end details namespace 
 
+  inline std::ostream& operator<< (std::ostream& os, const PolyTree64& pp)
+  {
+    PolyPath64List::const_iterator it = pp.begin();
+    for (; it < pp.end() - 1; ++it)
+      details::OutlinePolyPath64(os, **it, "   ", false);
+    details::OutlinePolyPath64(os, **it, "   ", true);
+    os << std::endl << std::endl;
+    if (!pp.Level()) os << std::endl;
+    return os;
+  }
+
+  inline std::ostream& operator<< (std::ostream& os, const PolyTreeD& pp)
+  {
+    PolyPathDList::const_iterator it = pp.begin();
+    for (; it < pp.end() - 1; ++it)
+      details::OutlinePolyPathD(os, **it, "   ", false);
+    details::OutlinePolyPathD(os, **it, "   ", true);
+    os << std::endl << std::endl;
+    if (!pp.Level()) os << std::endl;
+    return os;
+  }
+
   inline Paths64 PolyTreeToPaths64(const PolyTree64& polytree)
   {
     Paths64 result;
-    for (auto child : polytree)
+    for (const auto& child : polytree)
-      details::PolyPathToPaths64(*(PolyPath64*)(child), result);
+      details::PolyPathToPaths64(*child, result);
     return result;
   }
 
   inline PathsD PolyTreeToPathsD(const PolyTreeD& polytree)
   {
     PathsD result;
-    for (auto child : polytree)
+    for (const auto& child : polytree)
-      details::PolyPathToPathsD(*(PolyPathD*)(child), result);
+      details::PolyPathToPathsD(*child, result);
     return result;
   }
 
   inline bool CheckPolytreeFullyContainsChildren(const PolyTree64& polytree)
   {
-    for (auto child : polytree)
+    for (const auto& child : polytree)
       if (child->Count() > 0 && 
-        !details::PolyPath64ContainsChildren(*(PolyPath64*)(child)))
+        !details::PolyPath64ContainsChildren(*child))
           return false;
     return true;
   }
 
-  inline Path64 MakePath(const std::string& s)
+  namespace details {
-  {
+
-    const std::string skip_chars = " ,(){}[]";
+    template<typename T, typename U>
-    Path64 result;
+    inline constexpr void MakePathGeneric(const T list, size_t size,
-    std::string::const_iterator s_iter = s.cbegin();
+      std::vector<U>& result)
-    details::SkipUserDefinedChars(s_iter, s.cend(), skip_chars);
-    while (s_iter != s.cend())
     {
-      int64_t y = 0, x = 0;
+      for (size_t i = 0; i < size; ++i)
-      if (!details::GetInt(s_iter, s.cend(), x)) break;
+#ifdef USINGZ
-      details::SkipSpacesWithOptionalComma(s_iter, s.cend());
+        result[i / 2] = U{list[i], list[++i], 0};
-      if (!details::GetInt(s_iter, s.cend(), y)) break;
+#else
-      result.push_back(Point64(x, y));
+        result[i / 2] = U{list[i], list[++i]};
-      details::SkipUserDefinedChars(s_iter, s.cend(), skip_chars);
+#endif
     }
+
+  } // end details namespace
+
+  template<typename T,
+    typename std::enable_if<
+      std::is_integral<T>::value &&
+      !std::is_same<char, T>::value, bool
+    >::type = true>
+  inline Path64 MakePath(const std::vector<T>& list)
+  {
+    const auto size = list.size() - list.size() % 2;
+    if (list.size() != size)
+      DoError(non_pair_error_i);  // non-fatal without exception handling
+    Path64 result(size / 2);      // else ignores unpaired value
+    details::MakePathGeneric(list, size, result);
     return result;
   }
-  
+
-  inline PathD MakePathD(const std::string& s)
+  template<typename T, std::size_t N,
+    typename std::enable_if<
+      std::is_integral<T>::value &&
+      !std::is_same<char, T>::value, bool
+    >::type = true>
+  inline Path64 MakePath(const T(&list)[N])
   {
-    const std::string skip_chars = " ,(){}[]";
+    // Make the compiler error on unpaired value (i.e. no runtime effects).
-    PathD result;
+    static_assert(N % 2 == 0, "MakePath requires an even number of arguments");
-    std::string::const_iterator s_iter = s.cbegin();
+    Path64 result(N / 2);
-    details::SkipUserDefinedChars(s_iter, s.cend(), skip_chars);
+    details::MakePathGeneric(list, N, result);
-    while (s_iter != s.cend())
+    return result;
-    {
+  }
-      double y = 0, x = 0;
+
-      if (!details::GetFloat(s_iter, s.cend(), x)) break;
+  template<typename T,
-      details::SkipSpacesWithOptionalComma(s_iter, s.cend());
+    typename std::enable_if<
-      if (!details::GetFloat(s_iter, s.cend(), y)) break;
+      std::is_arithmetic<T>::value &&
-      result.push_back(PointD(x, y));
+      !std::is_same<char, T>::value, bool
-      details::SkipUserDefinedChars(s_iter, s.cend(), skip_chars);
+    >::type = true>
-    }
+  inline PathD MakePathD(const std::vector<T>& list)
+  {
+    const auto size = list.size() - list.size() % 2;
+    if (list.size() != size)
+      DoError(non_pair_error_i);  // non-fatal without exception handling
+    PathD result(size / 2);       // else ignores unpaired value
+    details::MakePathGeneric(list, size, result);
+    return result;
+  }
+
+  template<typename T, std::size_t N,
+    typename std::enable_if<
+      std::is_arithmetic<T>::value &&
+      !std::is_same<char, T>::value, bool
+    >::type = true>
+  inline PathD MakePathD(const T(&list)[N])
+  {
+    // Make the compiler error on unpaired value (i.e. no runtime effects).
+    static_assert(N % 2 == 0, "MakePath requires an even number of arguments");
+    PathD result(N / 2);
+    details::MakePathGeneric(list, N, result);
     return result;
   }
 
@@ -641,12 +538,14 @@ namespace Clipper2Lib {
 
   inline PathD TrimCollinear(const PathD& path, int precision, bool is_open_path = false)
   {
-    if (precision > 8 || precision < -8) 
+    int error_code = 0;
-      throw Clipper2Exception(precision_error);
+    CheckPrecision(precision, error_code);
+    if (error_code) return PathD();
     const double scale = std::pow(10, precision);
-    Path64 p = ScalePath<int64_t, double>(path, scale);
+    Path64 p = ScalePath<int64_t, double>(path, scale, error_code);
+    if (error_code) return PathD();
     p = TrimCollinear(p, is_open_path);
-    return ScalePath<double, int64_t>(p, 1/scale);
+    return ScalePath<double, int64_t>(p, 1/scale, error_code);
   }
 
   template <typename T>
@@ -721,6 +620,108 @@ namespace Clipper2Lib {
     return Sqr(a * d - c * b) / (c * c + d * d);
   }
 
+  inline size_t GetNext(size_t current, size_t high, 
+    const std::vector<bool>& flags)
+  {
+    ++current;
+    while (current <= high && flags[current]) ++current;
+    if (current <= high) return current;
+    current = 0;
+    while (flags[current]) ++current;
+    return current;
+  }
+
+  inline size_t GetPrior(size_t current, size_t high, 
+    const std::vector<bool>& flags)
+  {
+    if (current == 0) current = high;
+    else --current;
+    while (current > 0 && flags[current]) --current;
+    if (!flags[current]) return current;
+    current = high;
+    while (flags[current]) --current;
+    return current;
+  }
+
+  template <typename T>
+  inline Path<T> SimplifyPath(const Path<T> path, 
+    double epsilon, bool isOpenPath = false)
+  {
+    const size_t len = path.size(), high = len -1;
+    const double epsSqr = Sqr(epsilon);
+    if (len < 4) return Path<T>(path);
+
+    std::vector<bool> flags(len);
+    std::vector<double> distSqr(len);
+    size_t prior = high, curr = 0, start, next, prior2, next2;
+    if (isOpenPath)
+    {
+      distSqr[0] = MAX_DBL;
+      distSqr[high] = MAX_DBL;
+    }
+    else 
+    {
+      distSqr[0] = PerpendicDistFromLineSqrd(path[0], path[high], path[1]);
+      distSqr[high] = PerpendicDistFromLineSqrd(path[high], path[0], path[high - 1]);
+    }
+    for (size_t i = 1; i < high; ++i)
+      distSqr[i] = PerpendicDistFromLineSqrd(path[i], path[i - 1], path[i + 1]);
+
+    for (;;)
+    {
+      if (distSqr[curr] > epsSqr)
+      {
+        start = curr;
+        do
+        {
+          curr = GetNext(curr, high, flags);
+        } while (curr != start && distSqr[curr] > epsSqr);
+        if (curr == start) break;
+      }
+      
+      prior = GetPrior(curr, high, flags);
+      next = GetNext(curr, high, flags);
+      if (next == prior) break;
+
+      if (distSqr[next] < distSqr[curr])
+      {
+        flags[next] = true;
+        next = GetNext(next, high, flags);
+        next2 = GetNext(next, high, flags);
+        distSqr[curr] = PerpendicDistFromLineSqrd(path[curr], path[prior], path[next]);
+        if (next != high || !isOpenPath)
+          distSqr[next] = PerpendicDistFromLineSqrd(path[next], path[curr], path[next2]);
+        curr = next;
+      }
+      else
+      {
+        flags[curr] = true;
+        curr = next;
+        next = GetNext(next, high, flags);
+        prior2 = GetPrior(prior, high, flags);
+        distSqr[curr] = PerpendicDistFromLineSqrd(path[curr], path[prior], path[next]);
+        if (prior != 0 || !isOpenPath)
+          distSqr[prior] = PerpendicDistFromLineSqrd(path[prior], path[prior2], path[curr]);
+      }
+    }
+    Path<T> result;
+    result.reserve(len);
+    for (typename Path<T>::size_type i = 0; i < len; ++i)
+      if (!flags[i]) result.push_back(path[i]);
+    return result;
+  }
+
+  template <typename T>
+  inline Paths<T> SimplifyPaths(const Paths<T> paths, 
+    double epsilon, bool isOpenPath = false)
+  {
+    Paths<T> result;
+    result.reserve(paths.size());
+    for (const auto& path : paths)
+      result.push_back(SimplifyPath(path, epsilon, isOpenPath));
+    return result;
+  }
+
   template <typename T>
   inline void RDP(const Path<T> path, std::size_t begin,
     std::size_t end, double epsSqrd, std::vector<bool>& flags)
@@ -764,8 +765,9 @@ namespace Clipper2Lib {
   {
     Paths<T> result;
     result.reserve(paths.size());
-    for (const Path<T>& path : paths)
+    std::transform(paths.begin(), paths.end(), back_inserter(result),
-      result.push_back(RamerDouglasPeucker<T>(path, epsilon));
+      [epsilon](const auto& path)
+      { return RamerDouglasPeucker<T>(path, epsilon); });
     return result;
   }
 

thirdparty/clipper2/Clipper2Lib/include/clipper2/clipper.minkowski.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  15 October 2022                                                 *
+* Date      :  28 January 2023                                                 *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Minkowski Sum and Difference                                    *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -92,11 +92,12 @@ namespace Clipper2Lib
 
   inline PathsD MinkowskiSum(const PathD& pattern, const PathD& path, bool isClosed, int decimalPlaces = 2)
   {
+    int error_code = 0;
     double scale = pow(10, decimalPlaces);
-    Path64 pat64 = ScalePath<int64_t, double>(pattern, scale);
+    Path64 pat64 = ScalePath<int64_t, double>(pattern, scale, error_code);
-    Path64 path64 = ScalePath<int64_t, double>(path, scale);
+    Path64 path64 = ScalePath<int64_t, double>(path, scale, error_code);
     Paths64 tmp = detail::Union(detail::Minkowski(pat64, path64, true, isClosed), FillRule::NonZero);
-    return ScalePaths<double, int64_t>(tmp, 1 / scale);
+    return ScalePaths<double, int64_t>(tmp, 1 / scale, error_code);
   }
 
   inline Paths64 MinkowskiDiff(const Path64& pattern, const Path64& path, bool isClosed)
@@ -106,11 +107,12 @@ namespace Clipper2Lib
 
   inline PathsD MinkowskiDiff(const PathD& pattern, const PathD& path, bool isClosed, int decimalPlaces = 2)
   {
+    int error_code = 0;
     double scale = pow(10, decimalPlaces);
-    Path64 pat64 = ScalePath<int64_t, double>(pattern, scale); 
+    Path64 pat64 = ScalePath<int64_t, double>(pattern, scale, error_code);
-    Path64 path64 = ScalePath<int64_t, double>(path, scale);
+    Path64 path64 = ScalePath<int64_t, double>(path, scale, error_code);
     Paths64 tmp = detail::Union(detail::Minkowski(pat64, path64, false, isClosed), FillRule::NonZero);
-    return ScalePaths<double, int64_t>(tmp, 1 / scale);
+    return ScalePaths<double, int64_t>(tmp, 1 / scale, error_code);
   }
 
 } // Clipper2Lib namespace

thirdparty/clipper2/Clipper2Lib/include/clipper2/clipper.offset.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  15 October 2022                                                 *
+* Date      :  22 March 2023                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -11,6 +11,7 @@
 #define CLIPPER_OFFSET_H_
 
 #include "clipper.core.h"
+#include "clipper.engine.h"
 
 namespace Clipper2Lib {
 
@@ -23,47 +24,57 @@ enum class EndType {Polygon, Joined, Butt, Square, Round};
 //Joined : offsets both sides of a path, with joined ends
 //Polygon: offsets only one side of a closed path
 
+
 class ClipperOffset {
 private:
 
 	class Group {
 	public:
-		Paths64 paths_in_;
+		Paths64 paths_in;
-		Paths64 paths_out_;
+		Paths64 paths_out;
-		Path64 path_;
+		Path64 path;
-		bool is_reversed_ = false;
+		bool is_reversed = false;
-		JoinType join_type_;
+		JoinType join_type;
-		EndType end_type_;
+		EndType end_type;
-		Group(const Paths64& paths, JoinType join_type, EndType end_type) :
+		Group(const Paths64& _paths, JoinType _join_type, EndType _end_type) :
-			paths_in_(paths), join_type_(join_type), end_type_(end_type) {}
+			paths_in(_paths), join_type(_join_type), end_type(_end_type) {}
 	};
 
+	int   error_code_ = 0;
+	double delta_ = 0.0;
 	double group_delta_ = 0.0;
 	double abs_group_delta_ = 0.0;
 	double temp_lim_ = 0.0;
 	double steps_per_rad_ = 0.0;
+	double step_sin_ = 0.0;
+	double step_cos_ = 0.0;
 	PathD norms;
 	Paths64 solution;
 	std::vector<Group> groups_;
 	JoinType join_type_ = JoinType::Square;
-	
+	EndType end_type_ = EndType::Polygon;
+
 	double miter_limit_ = 0.0;
 	double arc_tolerance_ = 0.0;
-	bool merge_groups_ = true;
 	bool preserve_collinear_ = false;
 	bool reverse_solution_ = false;
 
+#ifdef USINGZ
+	ZCallback64 zCallback64_ = nullptr;
+#endif
+
 	void DoSquare(Group& group, const Path64& path, size_t j, size_t k);
 	void DoMiter(Group& group, const Path64& path, size_t j, size_t k, double cos_a);
 	void DoRound(Group& group, const Path64& path, size_t j, size_t k, double angle);
 	void BuildNormals(const Path64& path);
 	void OffsetPolygon(Group& group, Path64& path);
 	void OffsetOpenJoined(Group& group, Path64& path);
-	void OffsetOpenPath(Group& group, Path64& path, EndType endType);
+	void OffsetOpenPath(Group& group, Path64& path);
 	void OffsetPoint(Group& group, Path64& path, size_t j, size_t& k);
-	void DoGroupOffset(Group &group, double delta);
+	void DoGroupOffset(Group &group);
+	void ExecuteInternal(double delta);
 public:
-	ClipperOffset(double miter_limit = 2.0,
+	explicit ClipperOffset(double miter_limit = 2.0,
 		double arc_tolerance = 0.0,
 		bool preserve_collinear = false, 
 		bool reverse_solution = false) :
@@ -73,13 +84,13 @@ public:
 
 	~ClipperOffset() { Clear(); };
 
+	int ErrorCode() { return error_code_; };
 	void AddPath(const Path64& path, JoinType jt_, EndType et_);
 	void AddPaths(const Paths64& paths, JoinType jt_, EndType et_);
-	void AddPath(const PathD &p, JoinType jt_, EndType et_);
-	void AddPaths(const PathsD &p, JoinType jt_, EndType et_);
 	void Clear() { groups_.clear(); norms.clear(); };
 	
-	Paths64 Execute(double delta);
+	void Execute(double delta, Paths64& paths);
+	void Execute(double delta, PolyTree64& polytree);
 
 	double MiterLimit() const { return miter_limit_; }
 	void MiterLimit(double miter_limit) { miter_limit_ = miter_limit; }
@@ -88,19 +99,15 @@ public:
 	double ArcTolerance() const { return arc_tolerance_; }
 	void ArcTolerance(double arc_tolerance) { arc_tolerance_ = arc_tolerance; }
 
-	//MergeGroups: A path group is one or more paths added via the AddPath or
-	//AddPaths methods. By default these path groups will be offset
-	//independently of other groups and this may cause overlaps (intersections).
-	//However, when MergeGroups is enabled, any overlapping offsets will be
-	//merged (via a clipping union operation) to remove overlaps.
-	bool MergeGroups() const { return merge_groups_; }
-	void MergeGroups(bool merge_groups) { merge_groups_ = merge_groups; }
-
 	bool PreserveCollinear() const { return preserve_collinear_; }
 	void PreserveCollinear(bool preserve_collinear){preserve_collinear_ = preserve_collinear;}
 	
 	bool ReverseSolution() const { return reverse_solution_; }
 	void ReverseSolution(bool reverse_solution) {reverse_solution_ = reverse_solution;}
+
+#ifdef USINGZ
+	void SetZCallback(ZCallback64 cb) { zCallback64_ = cb; }
+#endif
 };
 
 }

thirdparty/clipper2/Clipper2Lib/include/clipper2/clipper.rectclip.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  26 October 2022                                                 *
+* Date      :  9 February 2023                                                 *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  FAST rectangular clipping                                       *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -12,38 +12,70 @@
 
 #include <cstdlib>
 #include <vector>
+#include <queue>
 #include "clipper.h"
 #include "clipper.core.h"
 
-namespace Clipper2Lib 
+namespace Clipper2Lib
 {
 
   enum class Location { Left, Top, Right, Bottom, Inside };
 
+  class OutPt2;
+  typedef std::vector<OutPt2*> OutPt2List;
+
+  class OutPt2 {
+  public:
+    Point64 pt;
+    size_t owner_idx;
+    OutPt2List* edge;
+    OutPt2* next;
+    OutPt2* prev;
+  };
+
+  //------------------------------------------------------------------------------
+  // RectClip
+  //------------------------------------------------------------------------------
+
   class RectClip {
+  private:
+    void ExecuteInternal(const Path64& path);
+    Path64 GetPath(OutPt2*& op);
   protected:
     const Rect64 rect_;
-    const Point64 mp_;
+    const Path64 rect_as_path_;
-    const Path64 rectPath_;
+    const Point64 rect_mp_;
-    Path64 result_;
+    Rect64 path_bounds_;
+    std::deque<OutPt2> op_container_;
+    OutPt2List results_;  // each path can be broken into multiples
+    OutPt2List edges_[8]; // clockwise and counter-clockwise
     std::vector<Location> start_locs_;
-
+    void CheckEdges();
+    void TidyEdges(int idx, OutPt2List& cw, OutPt2List& ccw);
     void GetNextLocation(const Path64& path,
       Location& loc, int& i, int highI);
+    OutPt2* Add(Point64 pt, bool start_new = false);
     void AddCorner(Location prev, Location curr);
     void AddCorner(Location& loc, bool isClockwise);
   public:
-    RectClip(const Rect64& rect) :
+    explicit RectClip(const Rect64& rect) :
       rect_(rect),
-      mp_(rect.MidPoint()),
+      rect_as_path_(rect.AsPath()),
-      rectPath_(rect.AsPath()) {}
+      rect_mp_(rect.MidPoint()) {}
-    Path64 Execute(const Path64& path);
+    Paths64 Execute(const Paths64& paths, bool convex_only = false);
   };
 
+  //------------------------------------------------------------------------------
+  // RectClipLines
+  //------------------------------------------------------------------------------
+
   class RectClipLines : public RectClip {
+  private:
+    void ExecuteInternal(const Path64& path);
+    Path64 GetPath(OutPt2*& op);
   public:
-    RectClipLines(const Rect64& rect) : RectClip(rect) {};
+    explicit RectClipLines(const Rect64& rect) : RectClip(rect) {};
-    Paths64 Execute(const Path64& path);
+    Paths64 Execute(const Paths64& paths);
   };
 
 } // Clipper2Lib namespace

thirdparty/clipper2/Clipper2Lib/src/clipper.offset.cpp

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  15 October 2022                                                 *
+* Date      :  22 March 2023                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -20,20 +20,38 @@ const double floating_point_tolerance = 1e-12;
 // Miscellaneous methods
 //------------------------------------------------------------------------------
 
-Paths64::size_type GetLowestPolygonIdx(const Paths64& paths)
+void GetBoundsAndLowestPolyIdx(const Paths64& paths, Rect64& r, int & idx)
 {
-	Paths64::size_type result = 0;
+	idx = -1;
-	Point64 lp = Point64(static_cast<int64_t>(0), 
+	r = MaxInvalidRect64;
-		std::numeric_limits<int64_t>::min());
+	int64_t lpx = 0;
-
+	for (int i = 0; i < static_cast<int>(paths.size()); ++i)
-	for (Paths64::size_type i = 0 ; i < paths.size(); ++i)
 		for (const Point64& p : paths[i])
-		{ 
+		{
-			if (p.y < lp.y || (p.y == lp.y && p.x >= lp.x)) continue;
+			if (p.y >= r.bottom)
-			result = i;
+			{
-			lp = p;
+				if (p.y > r.bottom || p.x < lpx)
-		}	
+				{
-	return result;
+					idx = i;
+					lpx = p.x;
+					r.bottom = p.y;
+				}
+			}
+			else if (p.y < r.top) r.top = p.y;
+			if (p.x > r.right) r.right = p.x;
+			else if (p.x < r.left) r.left = p.x;
+		}
+	//if (idx < 0) r = Rect64(0, 0, 0, 0);
+	//if (r.top == INT64_MIN) r.bottom = r.top;
+	//if (r.left == INT64_MIN) r.left = r.right;
+}
+
+bool IsSafeOffset(const Rect64& r, double abs_delta)
+{
+	return r.left > min_coord + abs_delta &&
+		r.right < max_coord - abs_delta &&
+		r.top > min_coord + abs_delta &&
+		r.bottom < max_coord - abs_delta;
 }
 
 PointD GetUnitNormal(const Point64& pt1, const Point64& pt2)
@@ -80,12 +98,32 @@ inline bool IsClosedPath(EndType et)
 
 inline Point64 GetPerpendic(const Point64& pt, const PointD& norm, double delta)
 {
+#ifdef USINGZ
+	return Point64(pt.x + norm.x * delta, pt.y + norm.y * delta, pt.z);
+#else
 	return Point64(pt.x + norm.x * delta, pt.y + norm.y * delta);
+#endif
 }
 
 inline PointD GetPerpendicD(const Point64& pt, const PointD& norm, double delta)
 {
+#ifdef USINGZ
+	return PointD(pt.x + norm.x * delta, pt.y + norm.y * delta, pt.z);
+#else
 	return PointD(pt.x + norm.x * delta, pt.y + norm.y * delta);
+#endif
+}
+
+inline void NegatePath(PathD& path)
+{
+	for (PointD& pt : path)
+	{
+		pt.x = -pt.x;
+		pt.y = -pt.y;
+#ifdef USINGZ
+		pt.z = pt.z;
+#endif
+	}
 }
 
 //------------------------------------------------------------------------------
@@ -105,19 +143,6 @@ void ClipperOffset::AddPaths(const Paths64 &paths, JoinType jt_, EndType et_)
 	groups_.push_back(Group(paths, jt_, et_));
 }
 
-void ClipperOffset::AddPath(const Clipper2Lib::PathD& path, JoinType jt_, EndType et_)
-{
-	PathsD paths;
-	paths.push_back(path);
-	AddPaths(paths, jt_, et_);
-}
-
-void ClipperOffset::AddPaths(const PathsD& paths, JoinType jt_, EndType et_)
-{
-	if (paths.size() == 0) return;
-	groups_.push_back(Group(PathsDToPaths64(paths), jt_, et_));
-}
-
 void ClipperOffset::BuildNormals(const Path64& path)
 {
 	norms.clear();
@@ -131,12 +156,20 @@ void ClipperOffset::BuildNormals(const Path64& path)
 
 inline PointD TranslatePoint(const PointD& pt, double dx, double dy)
 {
+#ifdef USINGZ
+	return PointD(pt.x + dx, pt.y + dy, pt.z);
+#else
 	return PointD(pt.x + dx, pt.y + dy);
+#endif
 }
 
 inline PointD ReflectPoint(const PointD& pt, const PointD& pivot)
 {
+#ifdef USINGZ
+	return PointD(pivot.x + (pivot.x - pt.x), pivot.y + (pivot.y - pt.y), pt.z);
+#else
 	return PointD(pivot.x + (pivot.x - pt.x), pivot.y + (pivot.y - pt.y));
+#endif
 }
 
 PointD IntersectPoint(const PointD& pt1a, const PointD& pt1b,
@@ -190,47 +223,68 @@ void ClipperOffset::DoSquare(Group& group, const Path64& path, size_t j, size_t
 	{
 		PointD pt4 = PointD(pt3.x + vec.x * group_delta_, pt3.y + vec.y * group_delta_);
 		PointD pt = IntersectPoint(pt1, pt2, pt3, pt4);
+#ifdef USINGZ
+		pt.z = ptQ.z;
+#endif
 		//get the second intersect point through reflecion
-		group.path_.push_back(Point64(ReflectPoint(pt, ptQ)));
+		group.path.push_back(Point64(ReflectPoint(pt, ptQ)));
-		group.path_.push_back(Point64(pt));
+		group.path.push_back(Point64(pt));
 	}
 	else
 	{
 		PointD pt4 = GetPerpendicD(path[j], norms[k], group_delta_);
 		PointD pt = IntersectPoint(pt1, pt2, pt3, pt4);
-		group.path_.push_back(Point64(pt));
+#ifdef USINGZ
+		pt.z = ptQ.z;
+#endif
+		group.path.push_back(Point64(pt));
 		//get the second intersect point through reflecion
-		group.path_.push_back(Point64(ReflectPoint(pt, ptQ)));
+		group.path.push_back(Point64(ReflectPoint(pt, ptQ)));
 	}
 }
 
 void ClipperOffset::DoMiter(Group& group, const Path64& path, size_t j, size_t k, double cos_a)
 {
 	double q = group_delta_ / (cos_a + 1);
-	group.path_.push_back(Point64(
+#ifdef USINGZ
+	group.path.push_back(Point64(
+		path[j].x + (norms[k].x + norms[j].x) * q,
+		path[j].y + (norms[k].y + norms[j].y) * q,
+		path[j].z));
+#else
+	group.path.push_back(Point64(
 		path[j].x + (norms[k].x + norms[j].x) * q,
 		path[j].y + (norms[k].y + norms[j].y) * q));
+#endif
 }
 
 void ClipperOffset::DoRound(Group& group, const Path64& path, size_t j, size_t k, double angle)
 {
-	//even though angle may be negative this is a convex join
 	Point64 pt = path[j];
-	int steps = static_cast<int>(std::ceil(steps_per_rad_ * std::abs(angle)));
+	PointD offsetVec = PointD(norms[k].x * group_delta_, norms[k].y * group_delta_);
-	double step_sin = std::sin(angle / steps);
-	double step_cos = std::cos(angle / steps);
-	
-	PointD pt2 = PointD(norms[k].x * group_delta_, norms[k].y * group_delta_);
-	if (j == k) pt2.Negate();
 
-	group.path_.push_back(Point64(pt.x + pt2.x, pt.y + pt2.y));
+	if (j == k) offsetVec.Negate();
-	for (int i = 0; i < steps; i++)
+#ifdef USINGZ
+	group.path.push_back(Point64(pt.x + offsetVec.x, pt.y + offsetVec.y, pt.z));
+#else
+	group.path.push_back(Point64(pt.x + offsetVec.x, pt.y + offsetVec.y));
+#endif
+	if (angle > -PI + 0.01)	// avoid 180deg concave
 	{
-		pt2 = PointD(pt2.x * step_cos - step_sin * pt2.y,
+		int steps = static_cast<int>(std::ceil(steps_per_rad_ * std::abs(angle))); // #448, #456
-			pt2.x * step_sin + pt2.y * step_cos);
+		for (int i = 1; i < steps; ++i) // ie 1 less than steps
-		group.path_.push_back(Point64(pt.x + pt2.x, pt.y + pt2.y));
+		{
+			offsetVec = PointD(offsetVec.x * step_cos_ - step_sin_ * offsetVec.y,
+				offsetVec.x * step_sin_ + offsetVec.y * step_cos_);
+#ifdef USINGZ
+			group.path.push_back(Point64(pt.x + offsetVec.x, pt.y + offsetVec.y, pt.z));
+#else
+			group.path.push_back(Point64(pt.x + offsetVec.x, pt.y + offsetVec.y));
+#endif
+
+		}
 	}
-	group.path_.push_back(GetPerpendic(path[j], norms[j], group_delta_));
+	group.path.push_back(GetPerpendic(path[j], norms[j], group_delta_));
 }
 
 void ClipperOffset::OffsetPoint(Group& group, Path64& path, size_t j, size_t& k)
@@ -248,72 +302,78 @@ void ClipperOffset::OffsetPoint(Group& group, Path64& path, size_t j, size_t& k)
 	if (sin_a > 1.0) sin_a = 1.0;
 	else if (sin_a < -1.0) sin_a = -1.0;
 
-	bool almostNoAngle = AlmostZero(sin_a) && cos_a > 0;
+	if (cos_a > 0.99) // almost straight - less than 8 degrees
-	// when there's almost no angle of deviation or it's concave
-	if (almostNoAngle || (sin_a * group_delta_ < 0))
 	{
-		Point64 p1 = Point64(
+		group.path.push_back(GetPerpendic(path[j], norms[k], group_delta_));
-			path[j].x + norms[k].x * group_delta_,
+		if (cos_a < 0.9998) // greater than 1 degree (#424)
-			path[j].y + norms[k].y * group_delta_);
+			group.path.push_back(GetPerpendic(path[j], norms[j], group_delta_)); // (#418)
-		Point64 p2 = Point64(
-			path[j].x + norms[j].x * group_delta_,
-			path[j].y + norms[j].y * group_delta_);
-		group.path_.push_back(p1);
-		if (p1 != p2)
-		{
-			// when concave add an extra vertex to ensure neat clipping
-			if (!almostNoAngle) group.path_.push_back(path[j]);
-			group.path_.push_back(p2);
-		}
 	}
-	else // it's convex 
+	else if (cos_a > -0.99 && (sin_a * group_delta_ < 0))
 	{
-		if (join_type_ == JoinType::Round)
+		// is concave
-			DoRound(group, path, j, k, std::atan2(sin_a, cos_a));
+		group.path.push_back(GetPerpendic(path[j], norms[k], group_delta_));
-		else if (join_type_ == JoinType::Miter)
+		// this extra point is the only (simple) way to ensure that
-		{
+		// path reversals are fully cleaned with the trailing clipper
-			// miter unless the angle is so acute the miter would exceeds ML
+		group.path.push_back(path[j]); // (#405)
-			if (cos_a > temp_lim_ - 1) DoMiter(group, path, j, k, cos_a);
+		group.path.push_back(GetPerpendic(path[j], norms[j], group_delta_));
-			else DoSquare(group, path, j, k);
+	}	
-		}
+	else if (join_type_ == JoinType::Round)
-		// don't bother squaring angles that deviate < ~20 degrees because
+		DoRound(group, path, j, k, std::atan2(sin_a, cos_a));
-		// squaring will be indistinguishable from mitering and just be a lot slower
+	else if (join_type_ == JoinType::Miter)
-		else if (cos_a > 0.9)
+	{
-			DoMiter(group, path, j, k, cos_a);			
+		// miter unless the angle is so acute the miter would exceeds ML
-		else
+		if (cos_a > temp_lim_ - 1) DoMiter(group, path, j, k, cos_a);
-			DoSquare(group, path, j, k);			
+		else DoSquare(group, path, j, k);
 	}
+	// don't bother squaring angles that deviate < ~20 degrees because
+	// squaring will be indistinguishable from mitering and just be a lot slower
+	else if (cos_a > 0.9)
+		DoMiter(group, path, j, k, cos_a);
+	else
+		DoSquare(group, path, j, k);
+
 	k = j;
 }
 
 void ClipperOffset::OffsetPolygon(Group& group, Path64& path)
 {
-	group.path_.clear();
 	for (Path64::size_type i = 0, j = path.size() -1; i < path.size(); j = i, ++i)
 		OffsetPoint(group, path, i, j);
-	group.paths_out_.push_back(group.path_);
+	group.paths_out.push_back(group.path);
 }
 
 void ClipperOffset::OffsetOpenJoined(Group& group, Path64& path)
 {
 	OffsetPolygon(group, path);
 	std::reverse(path.begin(), path.end());
-	BuildNormals(path);
+	
+	//rebuild normals // BuildNormals(path);
+	std::reverse(norms.begin(), norms.end());
+	norms.push_back(norms[0]);
+	norms.erase(norms.begin());
+	NegatePath(norms);
+
+	group.path.clear();
 	OffsetPolygon(group, path);
 }
 
-void ClipperOffset::OffsetOpenPath(Group& group, Path64& path, EndType end_type)
+void ClipperOffset::OffsetOpenPath(Group& group, Path64& path)
 {
-	group.path_.clear();
-
 	// do the line start cap
-	switch (end_type)
+	switch (end_type_)
 	{
 	case EndType::Butt:
-		group.path_.push_back(Point64(
+#ifdef USINGZ
+		group.path.push_back(Point64(
+			path[0].x - norms[0].x * group_delta_,
+			path[0].y - norms[0].y * group_delta_,
+			path[0].z));
+#else
+		group.path.push_back(Point64(
 			path[0].x - norms[0].x * group_delta_,
 			path[0].y - norms[0].y * group_delta_));
-		group.path_.push_back(GetPerpendic(path[0], norms[0], group_delta_));
+#endif
+		group.path.push_back(GetPerpendic(path[0], norms[0], group_delta_));
 		break;
 	case EndType::Round:
 		DoRound(group, path, 0,0, PI);
@@ -335,13 +395,20 @@ void ClipperOffset::OffsetOpenPath(Group& group, Path64& path, EndType end_type)
 	norms[0] = norms[highI];
 
 	// do the line end cap
-	switch (end_type)
+	switch (end_type_)
 	{
 	case EndType::Butt:
-		group.path_.push_back(Point64(
+#ifdef USINGZ
+		group.path.push_back(Point64(
+			path[highI].x - norms[highI].x * group_delta_,
+			path[highI].y - norms[highI].y * group_delta_,
+			path[highI].z));
+#else
+		group.path.push_back(Point64(
 			path[highI].x - norms[highI].x * group_delta_,
 			path[highI].y - norms[highI].y * group_delta_));
-		group.path_.push_back(GetPerpendic(path[highI], norms[highI], group_delta_));
+#endif
+		group.path.push_back(GetPerpendic(path[highI], norms[highI], group_delta_));
 		break;
 	case EndType::Round:
 		DoRound(group, path, highI, highI, PI);
@@ -353,133 +420,199 @@ void ClipperOffset::OffsetOpenPath(Group& group, Path64& path, EndType end_type)
 
 	for (size_t i = highI, k = 0; i > 0; --i)
 		OffsetPoint(group, path, i, k);
-	group.paths_out_.push_back(group.path_);
+	group.paths_out.push_back(group.path);
 }
 
-void ClipperOffset::DoGroupOffset(Group& group, double delta)
+void ClipperOffset::DoGroupOffset(Group& group)
 {
-	if (group.end_type_ != EndType::Polygon) delta = std::abs(delta) * 0.5;
+	Rect64 r;
-	bool isClosedPaths = IsClosedPath(group.end_type_);
+	int idx = -1;
+	//the lowermost polygon must be an outer polygon. So we can use that as the
+	//designated orientation for outer polygons (needed for tidy-up clipping)
+	GetBoundsAndLowestPolyIdx(group.paths_in, r, idx);
+	if (idx < 0) return;
 
-	if (isClosedPaths)
+	if (group.end_type == EndType::Polygon)
 	{
-		//the lowermost polygon must be an outer polygon. So we can use that as the
+		double area = Area(group.paths_in[idx]);
-		//designated orientation for outer polygons (needed for tidy-up clipping)
+		//if (area == 0) return; // probably unhelpful (#430)
-		Paths64::size_type lowestIdx = GetLowestPolygonIdx(group.paths_in_);
+		group.is_reversed = (area < 0);
-    // nb: don't use the default orientation here ...
+		if (group.is_reversed) group_delta_ = -delta_;
-		double area = Area(group.paths_in_[lowestIdx]);
+		else group_delta_ = delta_;
-		if (area == 0) return;	
-		group.is_reversed_ = (area < 0);
-		if (group.is_reversed_) delta = -delta;
 	} 
 	else
-		group.is_reversed_ = false;
-
-	group_delta_ = delta;
-	abs_group_delta_ = std::abs(group_delta_);
-	join_type_ = group.join_type_;
-
-	double arcTol = (arc_tolerance_ > floating_point_tolerance ? arc_tolerance_
-		: std::log10(2 + abs_group_delta_) * default_arc_tolerance); // empirically derived
-
-//calculate a sensible number of steps (for 360 deg for the given offset
-	if (group.join_type_ == JoinType::Round || group.end_type_ == EndType::Round)
 	{
-		steps_per_rad_ = PI / std::acos(1 - arcTol / abs_group_delta_) / (PI *2);
+		group.is_reversed = false;
+		group_delta_ = std::abs(delta_) * 0.5;
+	}
+	abs_group_delta_ = std::fabs(group_delta_);
+
+	// do range checking
+	if (!IsSafeOffset(r, abs_group_delta_))
+	{
+		DoError(range_error_i);
+		error_code_ |= range_error_i;
+		return;
 	}
 
-	bool is_closed_path = IsClosedPath(group.end_type_);
+	join_type_	= group.join_type;
-	Paths64::const_iterator path_iter;
+	end_type_ = group.end_type;
-	for(path_iter = group.paths_in_.cbegin(); path_iter != group.paths_in_.cend(); ++path_iter)
-	{
-		Path64 path = StripDuplicates(*path_iter, is_closed_path);
-		Path64::size_type cnt = path.size();
-		if (cnt == 0) continue;
 
+	//calculate a sensible number of steps (for 360 deg for the given offset
+	if (group.join_type == JoinType::Round || group.end_type == EndType::Round)
+	{
+		// arcTol - when arc_tolerance_ is undefined (0), the amount of 
+		// curve imprecision that's allowed is based on the size of the 
+		// offset (delta). Obviously very large offsets will almost always 
+		// require much less precision. See also offset_triginometry2.svg
+		double arcTol = (arc_tolerance_ > floating_point_tolerance ?
+			std::min(abs_group_delta_, arc_tolerance_) :
+			std::log10(2 + abs_group_delta_) * default_arc_tolerance); 
+		double steps_per_360 = PI / std::acos(1 - arcTol / abs_group_delta_);
+		if (steps_per_360 > abs_group_delta_ * PI)
+			steps_per_360 = abs_group_delta_ * PI;  //ie avoids excessive precision
+
+		step_sin_ = std::sin(2 * PI / steps_per_360);
+		step_cos_ = std::cos(2 * PI / steps_per_360);
+		if (group_delta_ < 0.0) step_sin_ = -step_sin_;		
+		steps_per_rad_ = steps_per_360 / (2 *PI);
+	}
+
+	bool is_joined =
+		(end_type_ == EndType::Polygon) ||
+		(end_type_ == EndType::Joined);
+	Paths64::const_iterator path_iter;
+	for(path_iter = group.paths_in.cbegin(); path_iter != group.paths_in.cend(); ++path_iter)
+	{
+		Path64 path = StripDuplicates(*path_iter, is_joined);
+		Path64::size_type cnt = path.size();
+		if (cnt == 0 || ((cnt < 3) && group.end_type == EndType::Polygon)) 
+			continue;
+
+		group.path.clear();
 		if (cnt == 1) // single point - only valid with open paths
 		{
-			group.path_ = Path64();
+			if (group_delta_ < 1) continue;
 			//single vertex so build a circle or square ...
-			if (group.join_type_ == JoinType::Round)
+			if (group.join_type == JoinType::Round)
 			{
 				double radius = abs_group_delta_;
-				group.path_ = Ellipse(path[0], radius, radius);
+				group.path = Ellipse(path[0], radius, radius);
+#ifdef USINGZ
+				for (auto& p : group.path) p.z = path[0].z;
+#endif
 			}
 			else
 			{
 				int d = (int)std::ceil(abs_group_delta_);
-				Rect64 r = Rect64(path[0].x - d, path[0].y - d, path[0].x + d, path[0].y + d);
+				r = Rect64(path[0].x - d, path[0].y - d, path[0].x + d, path[0].y + d);
-				group.path_ = r.AsPath();
+				group.path = r.AsPath();
+#ifdef USINGZ
+				for (auto& p : group.path) p.z = path[0].z;
+#endif
 			}
-			group.paths_out_.push_back(group.path_);
+			group.paths_out.push_back(group.path);
 		}
 		else
 		{
+			if ((cnt == 2) && (group.end_type == EndType::Joined))
+			{
+				if (group.join_type == JoinType::Round)
+					end_type_ = EndType::Round;
+				else
+					end_type_ = EndType::Square;
+			}
+
 			BuildNormals(path);
-			if (group.end_type_ == EndType::Polygon) OffsetPolygon(group, path);
+			if (end_type_ == EndType::Polygon) OffsetPolygon(group, path);
-			else if (group.end_type_ == EndType::Joined) OffsetOpenJoined(group, path);
+			else if (end_type_ == EndType::Joined) OffsetOpenJoined(group, path);
-			else OffsetOpenPath(group, path, group.end_type_);
+			else OffsetOpenPath(group, path);
 		}
 	}
-
+	solution.reserve(solution.size() + group.paths_out.size());
-	if (!merge_groups_)
+	copy(group.paths_out.begin(), group.paths_out.end(), back_inserter(solution));
-	{
+	group.paths_out.clear();
-		//clean up self-intersections ...
-		Clipper64 c;
-		c.PreserveCollinear = false;
-		//the solution should retain the orientation of the input
-		c.ReverseSolution = reverse_solution_ != group.is_reversed_;
-		c.AddSubject(group.paths_out_);
-		if (group.is_reversed_)
-			c.Execute(ClipType::Union, FillRule::Negative, group.paths_out_);
-		else
-			c.Execute(ClipType::Union, FillRule::Positive, group.paths_out_);
-	}
-
-	solution.reserve(solution.size() + group.paths_out_.size());
-	copy(group.paths_out_.begin(), group.paths_out_.end(), back_inserter(solution));
-	group.paths_out_.clear();
 }
 
-Paths64 ClipperOffset::Execute(double delta)
+void ClipperOffset::ExecuteInternal(double delta)
 {
+	error_code_ = 0;
 	solution.clear();
-	if (std::abs(delta) < default_arc_tolerance)
+	if (groups_.size() == 0) return;
+
+	if (std::abs(delta) < 0.5)
 	{
 		for (const Group& group : groups_)
 		{
-			solution.reserve(solution.size() + group.paths_in_.size());
+			solution.reserve(solution.size() + group.paths_in.size());
-			copy(group.paths_in_.begin(), group.paths_in_.end(), back_inserter(solution));
+			copy(group.paths_in.begin(), group.paths_in.end(), back_inserter(solution));
 		}
-		return solution;
+	} 
-	}
+	else
-
-	temp_lim_ = (miter_limit_ <= 1) ? 
-		2.0 : 
-		2.0 / (miter_limit_ * miter_limit_);
-
-	std::vector<Group>::iterator groups_iter;
-	for (groups_iter = groups_.begin(); 
-		groups_iter != groups_.end(); ++groups_iter)
 	{
-		DoGroupOffset(*groups_iter, delta);
+		temp_lim_ = (miter_limit_ <= 1) ?
-	}
+			2.0 :
+			2.0 / (miter_limit_ * miter_limit_);
 
-	if (merge_groups_ && groups_.size() > 0)
+		delta_ = delta;
-	{
+		std::vector<Group>::iterator git;
-		//clean up self-intersections ...
+		for (git = groups_.begin(); git != groups_.end(); ++git)
-		Clipper64 c;
+		{
-		c.PreserveCollinear = false;
+			DoGroupOffset(*git);
-		//the solution should retain the orientation of the input
+			if (!error_code_) continue; // all OK
-		c.ReverseSolution = reverse_solution_ != groups_[0].is_reversed_;
+			solution.clear();
-
+		}
-		c.AddSubject(solution);
-		if (groups_[0].is_reversed_)
-			c.Execute(ClipType::Union, FillRule::Negative, solution);
-		else
-			c.Execute(ClipType::Union, FillRule::Positive, solution);
 	}
-	return solution;
+}
+
+void ClipperOffset::Execute(double delta, Paths64& paths)
+{
+	paths.clear();
+
+	ExecuteInternal(delta);
+	if (!solution.size()) return;
+
+	paths = solution;
+	//clean up self-intersections ...
+	Clipper64 c;
+	c.PreserveCollinear = false;
+	//the solution should retain the orientation of the input
+	c.ReverseSolution = reverse_solution_ != groups_[0].is_reversed;
+#ifdef USINGZ
+	if (zCallback64_) {
+		c.SetZCallback(zCallback64_);
+	}
+#endif
+	c.AddSubject(solution);
+	if (groups_[0].is_reversed)
+		c.Execute(ClipType::Union, FillRule::Negative, paths);
+	else
+		c.Execute(ClipType::Union, FillRule::Positive, paths);
+}
+
+
+void ClipperOffset::Execute(double delta, PolyTree64& polytree)
+{
+	polytree.Clear();
+
+	ExecuteInternal(delta);
+	if (!solution.size()) return;
+
+	//clean up self-intersections ...
+	Clipper64 c;
+	c.PreserveCollinear = false;
+	//the solution should retain the orientation of the input
+	c.ReverseSolution = reverse_solution_ != groups_[0].is_reversed;
+#ifdef USINGZ
+	if (zCallback64_) {
+		c.SetZCallback(zCallback64_);
+	}
+#endif
+	c.AddSubject(solution);
+	if (groups_[0].is_reversed)
+		c.Execute(ClipType::Union, FillRule::Negative, polytree);
+	else
+		c.Execute(ClipType::Union, FillRule::Positive, polytree);
 }
 
 } // namespace

thirdparty/clipper2/Clipper2Lib/src/clipper.rectclip.cpp

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  26 October 2022                                                 *
+* Date      :  14 February 2023                                                *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  FAST rectangular clipping                                       *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -17,15 +17,22 @@ namespace Clipper2Lib {
   // Miscellaneous methods
   //------------------------------------------------------------------------------
 
-  inline PointInPolygonResult Path1ContainsPath2(Path64 path1, Path64 path2)
+  inline bool Path1ContainsPath2(const Path64& path1, const Path64& path2)
   {
-    PointInPolygonResult result = PointInPolygonResult::IsOn;
+    int io_count = 0;
-    for(const Point64& pt : path2)
+    // precondition: no (significant) overlap
+    for (const Point64& pt : path2)
     {
-      result = PointInPolygon(pt, path1);
+      PointInPolygonResult pip = PointInPolygon(pt, path1);
-      if (result != PointInPolygonResult::IsOn) break;
+      switch (pip) 
+      {
+      case PointInPolygonResult::IsOutside: ++io_count; break;
+        case PointInPolygonResult::IsInside: --io_count; break;
+        default: continue;
+      }
+      if (std::abs(io_count) > 1) break;
     }
-    return result;
+    return io_count <= 0;
   }
 
   inline bool GetLocation(const Rect64& rec,
@@ -59,39 +66,6 @@ namespace Clipper2Lib {
     return true;
   }
 
-  Point64 GetIntersectPoint64(const Point64& ln1a, const Point64& ln1b,
-    const Point64& ln2a, const Point64& ln2b)
-  {
-    // see http://astronomy.swin.edu.au/~pbourke/geometry/lineline2d/
-    if (ln1b.x == ln1a.x) 
-    {
-      if (ln2b.x == ln2a.x) return Point64(); // parallel lines
-      double m2 = static_cast<double>(ln2b.y - ln2a.y) / (ln2b.x - ln2a.x);
-      double b2 = ln2a.y - m2 * ln2a.x;
-      return Point64(ln1a.x, static_cast<int64_t>(std::round(m2 * ln1a.x + b2)));
-    }
-    else if (ln2b.x == ln2a.x)
-    {
-      double m1  = static_cast<double>(ln1b.y - ln1a.y) / (ln1b.x - ln1a.x);
-      double b1 = ln1a.y - m1 * ln1a.x;
-      return Point64(ln2a.x, static_cast<int64_t>(std::round(m1 * ln2a.x + b1)));
-    }
-    else
-    {
-      double m1 = static_cast<double>(ln1b.y - ln1a.y) / (ln1b.x - ln1a.x);
-      double b1 = ln1a.y - m1 * ln1a.x;
-      double m2 = static_cast<double>(ln2b.y - ln2a.y) / (ln2b.x - ln2a.x);
-      double b2 = ln2a.y - m2 * ln2a.x;
-      if (std::fabs(m1 - m2) > 1.0E-15)
-      {
-        double x = (b2 - b1) / (m1 - m2);
-        return Point64(x, m1 * x + b1);
-      }
-      else
-        return Point64((ln1a.x + ln1b.x) * 0.5, (ln1a.y + ln1b.y) * 0.5);
-    }
-  }
-
   inline bool GetIntersection(const Path64& rectPath,
     const Point64& p, const Point64& p2, Location& loc, Point64& ip)
   {
@@ -101,16 +75,16 @@ namespace Clipper2Lib {
     {
     case Location::Left:
       if (SegmentsIntersect(p, p2, rectPath[0], rectPath[3], true))
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[3], ip);
       else if (p.y < rectPath[0].y &&
         SegmentsIntersect(p, p2, rectPath[0], rectPath[1], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[1]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[1], ip);
         loc = Location::Top;
       }
       else if (SegmentsIntersect(p, p2, rectPath[2], rectPath[3], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[2], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[2], rectPath[3], ip);
         loc = Location::Bottom;
       }
       else return false;
@@ -118,34 +92,34 @@ namespace Clipper2Lib {
 
     case Location::Top:
       if (SegmentsIntersect(p, p2, rectPath[0], rectPath[1], true))
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[1]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[1], ip);
       else if (p.x < rectPath[0].x &&
         SegmentsIntersect(p, p2, rectPath[0], rectPath[3], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[3], ip);
         loc = Location::Left;
       }
       else if (p.x > rectPath[1].x &&
         SegmentsIntersect(p, p2, rectPath[1], rectPath[2], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[1], rectPath[2]);
+        GetIntersectPoint(p, p2, rectPath[1], rectPath[2], ip);
         loc = Location::Right;
       }
       else return false;
-        break;
+      break;
 
     case Location::Right:
       if (SegmentsIntersect(p, p2, rectPath[1], rectPath[2], true))
-        ip = GetIntersectPoint64(p, p2, rectPath[1], rectPath[2]);
+        GetIntersectPoint(p, p2, rectPath[1], rectPath[2], ip);
       else if (p.y < rectPath[0].y &&
         SegmentsIntersect(p, p2, rectPath[0], rectPath[1], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[1]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[1], ip);
         loc = Location::Top;
       }
       else if (SegmentsIntersect(p, p2, rectPath[2], rectPath[3], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[2], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[2], rectPath[3], ip);
         loc = Location::Bottom;
       }
       else return false;
@@ -153,17 +127,17 @@ namespace Clipper2Lib {
 
     case Location::Bottom:
       if (SegmentsIntersect(p, p2, rectPath[2], rectPath[3], true))
-        ip = GetIntersectPoint64(p, p2, rectPath[2], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[2], rectPath[3], ip);
       else if (p.x < rectPath[3].x &&
         SegmentsIntersect(p, p2, rectPath[0], rectPath[3], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[3], ip);
         loc = Location::Left;
       }
       else if (p.x > rectPath[2].x &&
         SegmentsIntersect(p, p2, rectPath[1], rectPath[2], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[1], rectPath[2]);
+        GetIntersectPoint(p, p2, rectPath[1], rectPath[2], ip);
         loc = Location::Right;
       }
       else return false;
@@ -172,28 +146,27 @@ namespace Clipper2Lib {
     default: // loc == rInside
       if (SegmentsIntersect(p, p2, rectPath[0], rectPath[3], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[3], ip);
         loc = Location::Left;
       }
       else if (SegmentsIntersect(p, p2, rectPath[0], rectPath[1], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[0], rectPath[1]);
+        GetIntersectPoint(p, p2, rectPath[0], rectPath[1], ip);
         loc = Location::Top;
       }
       else if (SegmentsIntersect(p, p2, rectPath[1], rectPath[2], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[1], rectPath[2]);
+        GetIntersectPoint(p, p2, rectPath[1], rectPath[2], ip);
         loc = Location::Right;
       }
       else if (SegmentsIntersect(p, p2, rectPath[2], rectPath[3], true))
       {
-        ip = GetIntersectPoint64(p, p2, rectPath[2], rectPath[3]);
+        GetIntersectPoint(p, p2, rectPath[2], rectPath[3], ip);
         loc = Location::Bottom;
       }
       else return false;
       break;
     }
-
     return true;
   }
 
@@ -214,7 +187,7 @@ namespace Clipper2Lib {
   }
 
   inline bool IsClockwise(Location prev, Location curr,
-    Point64 prev_pt, Point64 curr_pt, Point64 rect_mp)
+    const Point64& prev_pt, const Point64& curr_pt, const Point64& rect_mp)
   {
     if (AreOpposites(prev, curr))
       return CrossProduct(prev_pt, rect_mp, curr_pt) < 0;
@@ -222,34 +195,147 @@ namespace Clipper2Lib {
       return HeadingClockwise(prev, curr);
   }
 
+  inline OutPt2* UnlinkOp(OutPt2* op)
+  {
+    if (op->next == op) return nullptr;
+    op->prev->next = op->next;
+    op->next->prev = op->prev;
+    return op->next;
+  }
+
+  inline OutPt2* UnlinkOpBack(OutPt2* op)
+  {
+    if (op->next == op) return nullptr;
+    op->prev->next = op->next;
+    op->next->prev = op->prev;
+    return op->prev;
+  }
+
+  inline uint32_t GetEdgesForPt(const Point64& pt, const Rect64& rec)
+  {
+    uint32_t result = 0;
+    if (pt.x == rec.left) result = 1;
+    else if (pt.x == rec.right) result = 4;
+    if (pt.y == rec.top) result += 2;
+    else if (pt.y == rec.bottom) result += 8;
+    return result;
+  }
+
+  inline bool IsHeadingClockwise(const Point64& pt1, const Point64& pt2, int edgeIdx)
+  {
+    switch (edgeIdx)
+    {
+    case 0: return pt2.y < pt1.y;
+    case 1: return pt2.x > pt1.x;
+    case 2: return pt2.y > pt1.y;
+    default: return pt2.x < pt1.x;
+    }
+  }
+
+  inline bool HasHorzOverlap(const Point64& left1, const Point64& right1,
+    const Point64& left2, const Point64& right2)
+  {
+    return (left1.x < right2.x) && (right1.x > left2.x);
+  }
+
+  inline bool HasVertOverlap(const Point64& top1, const Point64& bottom1,
+    const Point64& top2, const Point64& bottom2)
+  {
+    return (top1.y < bottom2.y) && (bottom1.y > top2.y);
+  }
+
+  inline void AddToEdge(OutPt2List& edge, OutPt2* op)
+  {
+    if (op->edge) return;
+    op->edge = &edge;
+    edge.push_back(op);
+  }
+
+  inline void UncoupleEdge(OutPt2* op)
+  {
+    if (!op->edge) return;
+    for (size_t i = 0; i < op->edge->size(); ++i)
+    {
+      OutPt2* op2 = (*op->edge)[i];
+      if (op2 == op)
+      {
+        (*op->edge)[i] = nullptr;
+        break;
+      }
+    }
+    op->edge = nullptr;
+  }
+
+  inline void SetNewOwner(OutPt2* op, size_t new_idx)
+  {
+    op->owner_idx = new_idx;
+    OutPt2* op2 = op->next;
+    while (op2 != op)
+    {
+      op2->owner_idx = new_idx;
+      op2 = op2->next;
+    }
+  }
+
   //----------------------------------------------------------------------------
   // RectClip64
   //----------------------------------------------------------------------------
 
+  OutPt2* RectClip::Add(Point64 pt, bool start_new)
+  {
+    // this method is only called by InternalExecute.
+    // Later splitting & rejoining won't create additional op's,
+    // though they will change the (non-storage) results_ count.
+    int curr_idx = static_cast<int>(results_.size()) - 1;
+    OutPt2* result;
+    if (curr_idx < 0 || start_new)
+    {
+      result = &op_container_.emplace_back(OutPt2());
+      result->pt = pt;
+      result->next = result;
+      result->prev = result;
+      results_.push_back(result);
+    }
+    else
+    {
+      OutPt2* prevOp = results_[curr_idx];
+      if (prevOp->pt == pt)  return prevOp;
+      result = &op_container_.emplace_back(OutPt2());
+      result->owner_idx = curr_idx;
+      result->pt = pt;
+      result->next = prevOp->next;
+      prevOp->next->prev = result;
+      prevOp->next = result;
+      result->prev = prevOp;
+      results_[curr_idx] = result;
+    }
+    return result;
+  }
+
   void RectClip::AddCorner(Location prev, Location curr)
   {
     if (HeadingClockwise(prev, curr))
-      result_.push_back(rectPath_[static_cast<int>(prev)]);
+      Add(rect_as_path_[static_cast<int>(prev)]);
     else
-      result_.push_back(rectPath_[static_cast<int>(curr)]);
+      Add(rect_as_path_[static_cast<int>(curr)]);
   }
 
   void RectClip::AddCorner(Location& loc, bool isClockwise)
   {
     if (isClockwise)
     {
-      result_.push_back(rectPath_[static_cast<int>(loc)]);
+      Add(rect_as_path_[static_cast<int>(loc)]);
       loc = GetAdjacentLocation(loc, true);
     }
     else
     {
       loc = GetAdjacentLocation(loc, false);
-      result_.push_back(rectPath_[static_cast<int>(loc)]);
+      Add(rect_as_path_[static_cast<int>(loc)]);
     }
   }
 
   void RectClip::GetNextLocation(const Path64& path,
-      Location& loc, int& i, int highI)
+    Location& loc, int& i, int highI)
   {
     switch (loc)
     {
@@ -296,19 +382,15 @@ namespace Clipper2Lib {
         else if (path[i].x > rect_.right) loc = Location::Right;
         else if (path[i].y > rect_.bottom) loc = Location::Bottom;
         else if (path[i].y < rect_.top) loc = Location::Top;
-        else { result_.push_back(path[i]); ++i; continue; }
+        else { Add(path[i]); ++i; continue; }
         break; //inner loop
       }
       break;
     } //switch          
   }
 
-  Path64 RectClip::Execute(const Path64& path)
+  void RectClip::ExecuteInternal(const Path64& path)
   {
-    if (rect_.IsEmpty() || path.size() < 3) return Path64();
-
-    result_.clear();
-    start_locs_.clear();
     int i = 0, highI = static_cast<int>(path.size()) - 1;
     Location prev = Location::Inside, loc;
     Location crossing_loc = Location::Inside;
@@ -317,11 +399,16 @@ namespace Clipper2Lib {
     {
       i = highI - 1;
       while (i >= 0 && !GetLocation(rect_, path[i], prev)) --i;
-      if (i < 0) return path;
+      if (i < 0) 
+      {
+        // all of path must be inside fRect
+        for (const auto& pt : path) Add(pt);
+        return;
+      }
       if (prev == Location::Inside) loc = Location::Inside;
       i = 0;
     }
-    Location starting_loc = loc;
+    Location startingLoc = loc;
 
     ///////////////////////////////////////////////////
     while (i <= highI)
@@ -333,16 +420,18 @@ namespace Clipper2Lib {
 
       if (i > highI) break;
       Point64 ip, ip2;
-      Point64 prev_pt = (i) ? path[static_cast<size_t>(i - 1)] : path[highI];
+      Point64 prev_pt = (i) ? 
+        path[static_cast<size_t>(i - 1)] : 
+        path[highI];
 
       crossing_loc = loc;
-      if (!GetIntersection(rectPath_, path[i], prev_pt, crossing_loc, ip))
+      if (!GetIntersection(rect_as_path_, 
+        path[i], prev_pt, crossing_loc, ip))
       {
         // ie remaining outside
-
         if (crossing_prev == Location::Inside)
         {
-          bool isClockw = IsClockwise(prev, loc, prev_pt, path[i], mp_);
+          bool isClockw = IsClockwise(prev, loc, prev_pt, path[i], rect_mp_);
           do {
             start_locs_.push_back(prev);
             prev = GetAdjacentLocation(prev, isClockw);
@@ -351,7 +440,7 @@ namespace Clipper2Lib {
         }
         else if (prev != Location::Inside && prev != loc)
         {
-          bool isClockw = IsClockwise(prev, loc, prev_pt, path[i], mp_);
+          bool isClockw = IsClockwise(prev, loc, prev_pt, path[i], rect_mp_);
           do {
             AddCorner(prev, isClockw);
           } while (prev != loc);
@@ -373,7 +462,7 @@ namespace Clipper2Lib {
         }
         else if (prev != crossing_loc)
         {
-          bool isClockw = IsClockwise(prev, crossing_loc, prev_pt, path[i], mp_);
+          bool isClockw = IsClockwise(prev, crossing_loc, prev_pt, path[i], rect_mp_);
           do {
             AddCorner(prev, isClockw);
           } while (prev != crossing_loc);
@@ -384,7 +473,7 @@ namespace Clipper2Lib {
         // passing right through rect. 'ip' here will be the second 
         // intersect pt but we'll also need the first intersect pt (ip2)
         loc = prev;
-        GetIntersection(rectPath_, prev_pt, path[i], loc, ip2);
+        GetIntersection(rect_as_path_, prev_pt, path[i], loc, ip2);
         if (crossing_prev != Location::Inside)
           AddCorner(crossing_prev, loc);
 
@@ -395,7 +484,7 @@ namespace Clipper2Lib {
         }
 
         loc = crossing_loc;
-        result_.push_back(ip2);
+        Add(ip2);
         if (ip == ip2)
         {
           // it's very likely that path[i] is on rect
@@ -412,23 +501,33 @@ namespace Clipper2Lib {
           first_cross_ = crossing_loc;
       }
 
-      result_.push_back(ip);
+      Add(ip);
 
     } //while i <= highI
     ///////////////////////////////////////////////////
 
     if (first_cross_ == Location::Inside)
     {
-      if (starting_loc == Location::Inside) return path;
+      // path never intersects
-      Rect64 tmp_rect = Bounds(path);
+      if (startingLoc != Location::Inside)
-      if (tmp_rect.Contains(rect_) &&
+      {
-        Path1ContainsPath2(path, rectPath_) !=
+        // path is outside rect
-        PointInPolygonResult::IsOutside) return rectPath_;
+        // but being outside, it still may not contain rect
-      else
+        if (path_bounds_.Contains(rect_) &&
-        return Path64();
+          Path1ContainsPath2(path, rect_as_path_))
+        {
+          // yep, the path does fully contain rect
+          // so add rect to the solution
+          for (size_t j = 0; j < 4; ++j)
+          {
+            Add(rect_as_path_[j]);
+            // we may well need to do some splitting later, so
+            AddToEdge(edges_[j * 2], results_[0]);
+          }
+        }
+      }
     }
-
+    else if (loc != Location::Inside &&
-    if (loc != Location::Inside &&
       (loc != first_cross_ || start_locs_.size() > 2))
     {
       if (start_locs_.size() > 0)
@@ -445,54 +544,375 @@ namespace Clipper2Lib {
       if (loc != first_cross_)
         AddCorner(loc, HeadingClockwise(loc, first_cross_));
     }
-
-    if (result_.size() < 3) return Path64();
-
-    // tidy up duplicates and collinear segments
-    Path64 res;
-    res.reserve(result_.size());
-    size_t k = 0; highI = static_cast<int>(result_.size()) - 1;
-    Point64 prev_pt = result_[highI];
-    res.push_back(result_[0]);
-    Path64::const_iterator cit;
-    for (cit = result_.cbegin() + 1; cit != result_.cend(); ++cit)
-    {
-      if (CrossProduct(prev_pt, res[k], *cit))
-      {
-        prev_pt = res[k++];
-        res.push_back(*cit);
-      }
-      else
-        res[k] = *cit;
-    }
-
-    if (k < 2) return Path64();
-    // and a final check for collinearity
-    else if (!CrossProduct(res[0], res[k - 1], res[k])) res.pop_back();
-    return res;
   }
 
-  Paths64 RectClipLines::Execute(const Path64& path)
+  void RectClip::CheckEdges()
+  {
+    for (size_t i = 0; i < results_.size(); ++i)
+    {
+      OutPt2* op = results_[i];
+      if (!op) continue;
+      OutPt2* op2 = op;
+      do
+      {
+        if (!CrossProduct(op2->prev->pt,
+          op2->pt, op2->next->pt))
+        {
+          if (op2 == op)
+          {
+            op2 = UnlinkOpBack(op2);
+            if (!op2) break;
+            op = op2->prev;
+          }
+          else
+          {
+            op2 = UnlinkOpBack(op2);
+            if (!op2) break;
+          }
+        }
+        else
+          op2 = op2->next;
+      } while (op2 != op);
+
+      if (!op2)
+      {
+        results_[i] = nullptr;
+        continue;
+      }
+      results_[i] = op; // safety first
+
+      uint32_t edgeSet1 = GetEdgesForPt(op->prev->pt, rect_);
+      op2 = op;
+      do
+      {
+        uint32_t edgeSet2 = GetEdgesForPt(op2->pt, rect_);
+        if (edgeSet2 && !op2->edge)
+        {
+          uint32_t combinedSet = (edgeSet1 & edgeSet2);
+          for (int j = 0; j < 4; ++j)
+          {
+            if (combinedSet & (1 << j))
+            {
+              if (IsHeadingClockwise(op2->prev->pt, op2->pt, j))
+                AddToEdge(edges_[j * 2], op2);
+              else
+                AddToEdge(edges_[j * 2 + 1], op2);
+            }
+          }
+        }
+        edgeSet1 = edgeSet2;
+        op2 = op2->next;
+      } while (op2 != op);
+    }
+  }
+
+  void RectClip::TidyEdges(int idx, OutPt2List& cw, OutPt2List& ccw)
+  {
+    if (ccw.empty()) return;
+    bool isHorz = ((idx == 1) || (idx == 3));
+    bool cwIsTowardLarger = ((idx == 1) || (idx == 2));
+    size_t i = 0, j = 0;
+    OutPt2* p1, * p2, * p1a, * p2a, * op, * op2;
+
+    while (i < cw.size()) 
+    {
+      p1 = cw[i];
+      if (!p1 || p1->next == p1->prev)
+      {
+        cw[i++]->edge = nullptr;
+        j = 0;
+        continue;
+      }
+
+      size_t jLim = ccw.size();
+      while (j < jLim &&
+        (!ccw[j] || ccw[j]->next == ccw[j]->prev)) ++j;
+
+      if (j == jLim)
+      {
+        ++i;
+        j = 0;
+        continue;
+      }
+
+      if (cwIsTowardLarger)
+      {
+        // p1 >>>> p1a;
+        // p2 <<<< p2a;
+        p1 = cw[i]->prev;
+        p1a = cw[i];
+        p2 = ccw[j];
+        p2a = ccw[j]->prev;
+      }
+      else
+      {
+        // p1 <<<< p1a;
+        // p2 >>>> p2a;
+        p1 = cw[i];
+        p1a = cw[i]->prev;
+        p2 = ccw[j]->prev;
+        p2a = ccw[j];
+      }
+
+      if ((isHorz && !HasHorzOverlap(p1->pt, p1a->pt, p2->pt, p2a->pt)) ||
+        (!isHorz && !HasVertOverlap(p1->pt, p1a->pt, p2->pt, p2a->pt)))
+      {
+        ++j;
+        continue;
+      }
+
+      // to get here we're either splitting or rejoining
+      bool isRejoining = cw[i]->owner_idx != ccw[j]->owner_idx;
+
+      if (isRejoining)
+      {
+        results_[p2->owner_idx] = nullptr;
+        SetNewOwner(p2, p1->owner_idx);
+      }
+
+      // do the split or re-join
+      if (cwIsTowardLarger)
+      {
+        // p1 >> | >> p1a;
+        // p2 << | << p2a;
+        p1->next = p2;
+        p2->prev = p1;
+        p1a->prev = p2a;
+        p2a->next = p1a;
+      }
+      else
+      {
+        // p1 << | << p1a;
+        // p2 >> | >> p2a;
+        p1->prev = p2;
+        p2->next = p1;
+        p1a->next = p2a;
+        p2a->prev = p1a;
+      }
+
+      if (!isRejoining)
+      {
+        size_t new_idx = results_.size();
+        results_.push_back(p1a);
+        SetNewOwner(p1a, new_idx);
+      }
+
+      if (cwIsTowardLarger)
+      {
+        op = p2;
+        op2 = p1a;
+      }
+      else
+      {
+        op = p1;
+        op2 = p2a;
+      }
+      results_[op->owner_idx] = op;
+      results_[op2->owner_idx] = op2;
+
+      // and now lots of work to get ready for the next loop
+
+      bool opIsLarger, op2IsLarger;
+      if (isHorz) // X
+      {
+        opIsLarger = op->pt.x > op->prev->pt.x;
+        op2IsLarger = op2->pt.x > op2->prev->pt.x;
+      }
+      else       // Y
+      {
+        opIsLarger = op->pt.y > op->prev->pt.y;
+        op2IsLarger = op2->pt.y > op2->prev->pt.y;
+      }
+
+      if ((op->next == op->prev) ||
+        (op->pt == op->prev->pt))
+      {
+        if (op2IsLarger == cwIsTowardLarger)
+        {
+          cw[i] = op2;
+          ccw[j++] = nullptr;
+        }
+        else
+        {
+          ccw[j] = op2;
+          cw[i++] = nullptr;
+        }
+      }
+      else if ((op2->next == op2->prev) ||
+        (op2->pt == op2->prev->pt))
+      {
+        if (opIsLarger == cwIsTowardLarger)
+        {
+          cw[i] = op;
+          ccw[j++] = nullptr;
+        }
+        else
+        {
+          ccw[j] = op;
+          cw[i++] = nullptr;
+        }
+      }
+      else if (opIsLarger == op2IsLarger)
+      {
+        if (opIsLarger == cwIsTowardLarger)
+        {
+          cw[i] = op;
+          UncoupleEdge(op2);
+          AddToEdge(cw, op2);
+          ccw[j++] = nullptr;
+        }
+        else
+        {
+          cw[i++] = nullptr;
+          ccw[j] = op2;
+          UncoupleEdge(op);
+          AddToEdge(ccw, op);
+          j = 0;
+        }
+      }
+      else
+      {
+        if (opIsLarger == cwIsTowardLarger)
+          cw[i] = op;
+        else
+          ccw[j] = op;
+        if (op2IsLarger == cwIsTowardLarger)
+          cw[i] = op2;
+        else
+          ccw[j] = op2;
+      }
+    }
+  }
+
+  Path64 RectClip::GetPath(OutPt2*& op)
+  {
+    if (!op || op->next == op->prev) return Path64();
+
+    OutPt2* op2 = op->next;
+    while (op2 && op2 != op)
+    {
+      if (CrossProduct(op2->prev->pt, 
+        op2->pt, op2->next->pt) == 0)
+      {
+        op = op2->prev;
+        op2 = UnlinkOp(op2);
+      }
+      else
+        op2 = op2->next;
+    }
+    op = op2; // needed for op cleanup
+    if (!op2) return Path64();
+
+    Path64 result;
+    result.push_back(op->pt);
+    op2 = op->next;
+    while (op2 != op)
+    {
+      result.push_back(op2->pt);
+      op2 = op2->next;
+    }
+    return result;
+  }
+
+  Paths64 RectClip::Execute(const Paths64& paths, bool convex_only)
   {
-    result_.clear();
     Paths64 result;
-    if (rect_.IsEmpty() || path.size() == 0) return result;
+    if (rect_.IsEmpty()) return result;
+
+    for (const auto& path : paths)
+    {
+      if (path.size() < 3) continue;
+      path_bounds_ = GetBounds(path);
+      if (!rect_.Intersects(path_bounds_))
+        continue; // the path must be completely outside rect_
+      else if (rect_.Contains(path_bounds_))
+      {
+        // the path must be completely inside rect_
+        result.push_back(path);
+        continue;
+      }
+
+      ExecuteInternal(path);
+      if (!convex_only)
+      {
+        CheckEdges();
+        for (int i = 0; i < 4; ++i)
+          TidyEdges(i, edges_[i * 2], edges_[i * 2 + 1]);
+      }
+
+      for (OutPt2*& op :  results_)
+      {
+        Path64 tmp = GetPath(op);
+        if (!tmp.empty())
+          result.emplace_back(tmp);
+      }
+
+      //clean up after every loop
+      op_container_ = std::deque<OutPt2>();
+      results_.clear();
+      for (OutPt2List edge : edges_) edge.clear();
+      start_locs_.clear();
+    }
+    return result;
+  }
+
+  //------------------------------------------------------------------------------
+  // RectClipLines
+  //------------------------------------------------------------------------------
+
+  Paths64 RectClipLines::Execute(const Paths64& paths)
+  {
+    Paths64 result;
+    if (rect_.IsEmpty()) return result;
+
+    for (const auto& path : paths)
+    {
+      if (path.size() < 2) continue;
+      Rect64 pathrec = GetBounds(path);
+
+      if (!rect_.Intersects(pathrec)) continue;
+
+      ExecuteInternal(path);
+
+      for (OutPt2*& op : results_)
+      {
+        Path64 tmp = GetPath(op);
+        if (!tmp.empty())
+          result.emplace_back(tmp);
+      }
+      results_.clear();
+
+      op_container_ = std::deque<OutPt2>();
+      start_locs_.clear();
+    }
+    return result;
+  }
+
+  void RectClipLines::ExecuteInternal(const Path64& path)
+  {
+    if (rect_.IsEmpty() || path.size() < 2) return;
+
+    results_.clear();
+    op_container_ = std::deque<OutPt2>();
+    start_locs_.clear();
 
     int i = 1, highI = static_cast<int>(path.size()) - 1;
 
     Location prev = Location::Inside, loc;
-    Location crossing_loc = Location::Inside;
+    Location crossing_loc;
     if (!GetLocation(rect_, path[0], loc))
     {
       while (i <= highI && !GetLocation(rect_, path[i], prev)) ++i;
-      if (i > highI) {
+      if (i > highI) 
-        result.push_back(path);
+      {
-        return result;
+        // all of path must be inside fRect
+        for (const auto& pt : path) Add(pt);
+        return;
       }
       if (prev == Location::Inside) loc = Location::Inside;
       i = 1;
     }
-    if (loc == Location::Inside) result_.push_back(path[0]);
+    if (loc == Location::Inside) Add(path[0]);
 
     ///////////////////////////////////////////////////
     while (i <= highI)
@@ -504,7 +924,8 @@ namespace Clipper2Lib {
       Point64 prev_pt = path[static_cast<size_t>(i - 1)];
 
       crossing_loc = loc;
-      if (!GetIntersection(rectPath_, path[i], prev_pt, crossing_loc, ip))
+      if (!GetIntersection(rect_as_path_, 
+        path[i], prev_pt, crossing_loc, ip))
       {
         // ie remaining outside
         ++i;
@@ -517,30 +938,38 @@ namespace Clipper2Lib {
 
       if (loc == Location::Inside) // path must be entering rect
       {
-        result_.push_back(ip);
+        Add(ip, true);
       }
       else if (prev != Location::Inside)
       {
         // passing right through rect. 'ip' here will be the second 
         // intersect pt but we'll also need the first intersect pt (ip2)
         crossing_loc = prev;
-        GetIntersection(rectPath_, prev_pt, path[i], crossing_loc, ip2);
+        GetIntersection(rect_as_path_, 
-        result_.push_back(ip2);
+          prev_pt, path[i], crossing_loc, ip2);
-        result_.push_back(ip);
+        Add(ip2, true);
-        result.push_back(result_);
+        Add(ip);
-        result_.clear();
       }
       else // path must be exiting rect
       {
-        result_.push_back(ip);
+        Add(ip);
-        result.push_back(result_);
-        result_.clear();
       }
     } //while i <= highI
     ///////////////////////////////////////////////////
+  }
 
-    if (result_.size() > 1)
+  Path64 RectClipLines::GetPath(OutPt2*& op)
-      result.push_back(result_);
+  {
+    Path64 result;
+    if (!op || op == op->next) return result;
+    op = op->next; // starting at path beginning 
+    result.push_back(op->pt);
+    OutPt2 *op2 = op->next;
+    while (op2 != op)
+    {
+      result.push_back(op2->pt);
+      op2 = op2->next;
+    }        
     return result;
   }