clipper2: Update to 1.4.0

COPYRIGHT.txt

@@ -186,7 +186,7 @@ License: MPL-2.0
 
 Files: ./thirdparty/clipper2/
 Comment: Clipper2
-Copyright: 2010-2023, Angus Johnson
+Copyright: 2010-2024, Angus Johnson
 License: BSL-1.0
 
 Files: ./thirdparty/cvtt/

thirdparty/README.md

@@ -111,7 +111,7 @@ Files extracted from upstream source:
 ## clipper2
 
 - Upstream: https://github.com/AngusJohnson/Clipper2
-- Version: 1.3.0 (98db5662e8dd1808a5a7b50c5605a2289bb390e8, 2023)
+- Version: 1.4.0 (736ddb0b53d97fd5f65dd3d9bbf8a0993eaf387c, 2024)
 - License: BSL 1.0
 
 Files extracted from upstream source:

thirdparty/clipper2/include/clipper2/clipper.core.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  24 November 2023                                                *
+* Date      :  12 May 2024                                                     *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  Core Clipper Library structures and functions                   *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -19,6 +19,7 @@
 #include <algorithm>
 #include <climits>
 #include <numeric>
+#include <optional>
 #include "clipper2/clipper.version.h"
 
 #define CLIPPER2_THROW(exception) std::abort()
@@ -51,19 +52,19 @@ namespace Clipper2Lib
 
   // error codes (2^n)
   const int precision_error_i   = 1;  // non-fatal
-  const int scale_error_i       = 2;  // non-fatal 
-  const int non_pair_error_i    = 4;  // non-fatal 
-  const int undefined_error_i   = 32; // fatal 
+  const int scale_error_i       = 2;  // non-fatal
+  const int non_pair_error_i    = 4;  // non-fatal
+  const int undefined_error_i   = 32; // fatal
   const int range_error_i       = 64;
 
 #ifndef PI
   static const double PI = 3.141592653589793238;
 #endif
 
-#ifdef CLIPPER2_MAX_PRECISION
-  const int MAX_DECIMAL_PRECISION = CLIPPER2_MAX_PRECISION;
+#ifdef CLIPPER2_MAX_DECIMAL_PRECISION
+  const int CLIPPER2_MAX_DEC_PRECISION = CLIPPER2_MAX_DECIMAL_PRECISION;
 #else
-  const int MAX_DECIMAL_PRECISION = 8; // see Discussions #564
+  const int CLIPPER2_MAX_DEC_PRECISION = 8; // see Discussions #564
 #endif
 
   static const int64_t MAX_COORD = INT64_MAX >> 2;
@@ -74,7 +75,7 @@ namespace Clipper2Lib
 
   static const double MAX_DBL = (std::numeric_limits<double>::max)();
 
-  static void DoError(int error_code)
+  static void DoError([[maybe_unused]] int error_code)
   {
 #if (defined(__cpp_exceptions) && __cpp_exceptions) || (defined(__EXCEPTIONS) && __EXCEPTIONS)
     switch (error_code)
@@ -95,6 +96,13 @@ namespace Clipper2Lib
 #endif
   }
 
+  // can we call std::round on T? (default false) (#824)
+  template <typename T, typename = void>
+  struct is_round_invocable : std::false_type {};
+
+  template <typename T>
+  struct is_round_invocable<T, std::void_t<decltype(std::round(std::declval<T>()))>> : std::true_type {};
+
 
   //By far the most widely used filling rules for polygons are EvenOdd
   //and NonZero, sometimes called Alternate and Winding respectively.
@@ -113,8 +121,8 @@ namespace Clipper2Lib
     template <typename T2>
     inline void Init(const T2 x_ = 0, const T2 y_ = 0, const int64_t z_ = 0)
     {
-      if constexpr (std::numeric_limits<T>::is_integer &&
-        !std::numeric_limits<T2>::is_integer)
+      if constexpr (std::is_integral_v<T> &&
+        is_round_invocable<T2>::value && !std::is_integral_v<T2>)
       {
         x = static_cast<T>(std::round(x_));
         y = static_cast<T>(std::round(y_));
@@ -143,6 +151,12 @@ namespace Clipper2Lib
       Init(p.x, p.y, p.z);
     }
 
+    template <typename T2>
+    explicit Point(const Point<T2>& p, int64_t z_)
+    {
+      Init(p.x, p.y, z_);
+    }
+
     Point operator * (const double scale) const
     {
       return Point(x * scale, y * scale, z);
@@ -161,8 +175,8 @@ namespace Clipper2Lib
     template <typename T2>
     inline void Init(const T2 x_ = 0, const T2 y_ = 0)
     {
-      if constexpr (std::numeric_limits<T>::is_integer &&
-        !std::numeric_limits<T2>::is_integer)
+      if constexpr (std::is_integral_v<T> &&
+        is_round_invocable<T2>::value && !std::is_integral_v<T2>)
       {
         x = static_cast<T>(std::round(x_));
         y = static_cast<T>(std::round(y_));
@@ -244,6 +258,14 @@ namespace Clipper2Lib
     (std::numeric_limits<double>::max)(),
     (std::numeric_limits<double>::max)());
 
+  template<typename T>
+  static inline Point<T> MidPoint(const Point<T>& p1, const Point<T>& p2)
+  {
+    Point<T> result;
+    result.x = (p1.x + p2.x) / 2;
+    result.y = (p1.y + p2.y) / 2;
+    return result;
+  }
 
   // Rect ------------------------------------------------------------------------
 
@@ -275,10 +297,19 @@ namespace Clipper2Lib
       else
       {
         left = top = (std::numeric_limits<T>::max)();
-        right = bottom = (std::numeric_limits<T>::lowest)();
+        right = bottom = std::numeric_limits<T>::lowest();
       }
     }
 
+    static Rect<T> InvalidRect()
+    {
+      return {
+        (std::numeric_limits<T>::max)(),
+        (std::numeric_limits<T>::max)(),
+        std::numeric_limits<T>::lowest(),
+        std::numeric_limits<T>::lowest() };
+    }
+
     bool IsValid() const { return left != (std::numeric_limits<T>::max)(); }
 
     T Width() const { return right - left; }
@@ -329,7 +360,7 @@ namespace Clipper2Lib
     };
 
     bool operator==(const Rect<T>& other) const {
-      return left == other.left && right == other.right && 
+      return left == other.left && right == other.right &&
         top == other.top && bottom == other.bottom;
     }
 
@@ -344,8 +375,8 @@ namespace Clipper2Lib
   {
     Rect<T1> result;
 
-    if constexpr (std::numeric_limits<T1>::is_integer &&
-      !std::numeric_limits<T2>::is_integer)
+    if constexpr (std::is_integral_v<T1> &&
+      is_round_invocable<T2>::value && !std::is_integral_v<T2>)
     {
       result.left = static_cast<T1>(std::round(rect.left * scale));
       result.top = static_cast<T1>(std::round(rect.top * scale));
@@ -354,32 +385,24 @@ namespace Clipper2Lib
     }
     else
     {
-      result.left = rect.left * scale;
-      result.top = rect.top * scale;
-      result.right = rect.right * scale;
-      result.bottom = rect.bottom * scale;
+      result.left = static_cast<T1>(rect.left * scale);
+      result.top = static_cast<T1>(rect.top * scale);
+      result.right = static_cast<T1>(rect.right * scale);
+      result.bottom = static_cast<T1>(rect.bottom * scale);
     }
     return result;
   }
 
-  static const Rect64 InvalidRect64 = 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 InvalidRectD = RectD(
-    (std::numeric_limits<double>::max)(),
-    (std::numeric_limits<double>::max)(),
-    (std::numeric_limits<double>::lowest)(),
-    (std::numeric_limits<double>::lowest)());
+  static const Rect64 InvalidRect64 = Rect64::InvalidRect();
+  static const RectD InvalidRectD = RectD::InvalidRect();
 
   template <typename T>
   Rect<T> GetBounds(const Path<T>& path)
   {
-    auto xmin = (std::numeric_limits<T>::max)();
-    auto ymin = (std::numeric_limits<T>::max)();
-    auto xmax = std::numeric_limits<T>::lowest();
-    auto ymax = std::numeric_limits<T>::lowest();
+    T xmin = (std::numeric_limits<T>::max)();
+    T ymin = (std::numeric_limits<T>::max)();
+    T xmax = std::numeric_limits<T>::lowest();
+    T ymax = std::numeric_limits<T>::lowest();
     for (const auto& p : path)
     {
       if (p.x < xmin) xmin = p.x;
@@ -393,17 +416,52 @@ namespace Clipper2Lib
   template <typename T>
   Rect<T> GetBounds(const Paths<T>& paths)
   {
-    auto xmin = (std::numeric_limits<T>::max)();
-    auto ymin = (std::numeric_limits<T>::max)();
-    auto xmax = std::numeric_limits<T>::lowest();
-    auto ymax = std::numeric_limits<T>::lowest();
+    T xmin = (std::numeric_limits<T>::max)();
+    T ymin = (std::numeric_limits<T>::max)();
+    T xmax = std::numeric_limits<T>::lowest();
+    T ymax = std::numeric_limits<T>::lowest();
     for (const Path<T>& path : paths)
       for (const Point<T>& p : path)
       {
-      if (p.x < xmin) xmin = p.x;
-      if (p.x > xmax) xmax = p.x;
-      if (p.y < ymin) ymin = p.y;
-      if (p.y > ymax) ymax = p.y;
+        if (p.x < xmin) xmin = p.x;
+        if (p.x > xmax) xmax = p.x;
+        if (p.y < ymin) ymin = p.y;
+        if (p.y > ymax) ymax = p.y;
+      }
+    return Rect<T>(xmin, ymin, xmax, ymax);
+  }
+
+  template <typename T, typename T2>
+  Rect<T> GetBounds(const Path<T2>& path)
+  {
+    T xmin = (std::numeric_limits<T>::max)();
+    T ymin = (std::numeric_limits<T>::max)();
+    T xmax = std::numeric_limits<T>::lowest();
+    T ymax = std::numeric_limits<T>::lowest();
+    for (const auto& p : path)
+    {
+      if (p.x < xmin) xmin = static_cast<T>(p.x);
+      if (p.x > xmax) xmax = static_cast<T>(p.x);
+      if (p.y < ymin) ymin = static_cast<T>(p.y);
+      if (p.y > ymax) ymax = static_cast<T>(p.y);
+    }
+    return Rect<T>(xmin, ymin, xmax, ymax);
+  }
+
+  template <typename T, typename T2>
+  Rect<T> GetBounds(const Paths<T2>& paths)
+  {
+    T xmin = (std::numeric_limits<T>::max)();
+    T ymin = (std::numeric_limits<T>::max)();
+    T xmax = std::numeric_limits<T>::lowest();
+    T ymax = std::numeric_limits<T>::lowest();
+    for (const Path<T2>& path : paths)
+      for (const Point<T2>& p : path)
+      {
+        if (p.x < xmin) xmin = static_cast<T>(p.x);
+        if (p.x > xmax) xmax = static_cast<T>(p.x);
+        if (p.y < ymin) ymin = static_cast<T>(p.y);
+        if (p.y > ymax) ymax = static_cast<T>(p.y);
       }
     return Rect<T>(xmin, ymin, xmax, ymax);
   }
@@ -431,7 +489,7 @@ namespace Clipper2Lib
 
 
   template <typename T1, typename T2>
-  inline Path<T1> ScalePath(const Path<T2>& path, 
+  inline Path<T1> ScalePath(const Path<T2>& path,
     double scale_x, double scale_y, int& error_code)
   {
     Path<T1> result;
@@ -447,11 +505,11 @@ namespace Clipper2Lib
     result.reserve(path.size());
 #ifdef USINGZ
     std::transform(path.begin(), path.end(), back_inserter(result),
-      [scale_x, scale_y](const auto& pt) 
+      [scale_x, scale_y](const auto& pt)
       { return Point<T1>(pt.x * scale_x, pt.y * scale_y, pt.z); });
 #else
     std::transform(path.begin(), path.end(), back_inserter(result),
-      [scale_x, scale_y](const auto& pt) 
+      [scale_x, scale_y](const auto& pt)
       { return Point<T1>(pt.x * scale_x, pt.y * scale_y); });
 #endif
     return result;
@@ -465,20 +523,19 @@ namespace Clipper2Lib
   }
 
   template <typename T1, typename T2>
-  inline Paths<T1> ScalePaths(const Paths<T2>& paths, 
+  inline Paths<T1> ScalePaths(const Paths<T2>& paths,
     double scale_x, double scale_y, int& error_code)
   {
     Paths<T1> result;
 
-    if constexpr (std::numeric_limits<T1>::is_integer &&
-      !std::numeric_limits<T2>::is_integer)
+    if constexpr (std::is_integral_v<T1>)
     {
-      RectD r = GetBounds(paths);
+      RectD r = GetBounds<double, T2>(paths);
       if ((r.left * scale_x) < min_coord ||
         (r.right * scale_x) > max_coord ||
         (r.top * scale_y) < min_coord ||
         (r.bottom * scale_y) > max_coord)
-      { 
+      {
         error_code |= range_error_i;
         DoError(range_error_i);
         return result; // empty path
@@ -493,7 +550,7 @@ namespace Clipper2Lib
   }
 
   template <typename T1, typename T2>
-  inline Paths<T1> ScalePaths(const Paths<T2>& paths, 
+  inline Paths<T1> ScalePaths(const Paths<T2>& paths,
     double scale, int& error_code)
   {
     return ScalePaths<T1, T2>(paths, scale, scale, error_code);
@@ -590,20 +647,94 @@ namespace Clipper2Lib
 
   // Miscellaneous ------------------------------------------------------------
 
-  inline void CheckPrecision(int& precision, int& error_code)
+  inline void CheckPrecisionRange(int& precision, int& error_code)
   {
-    if (precision >= -MAX_DECIMAL_PRECISION && precision <= MAX_DECIMAL_PRECISION) return;
+    if (precision >= -CLIPPER2_MAX_DEC_PRECISION &&
+      precision <= CLIPPER2_MAX_DEC_PRECISION) return;
     error_code |= precision_error_i; // non-fatal error
-    DoError(precision_error_i);      // does nothing unless exceptions enabled
-    precision = precision > 0 ? MAX_DECIMAL_PRECISION : -MAX_DECIMAL_PRECISION;
+    DoError(precision_error_i);      // does nothing when exceptions are disabled
+    precision = precision > 0 ? CLIPPER2_MAX_DEC_PRECISION : -CLIPPER2_MAX_DEC_PRECISION;
   }
 
-  inline void CheckPrecision(int& precision)
+  inline void CheckPrecisionRange(int& precision)
   {
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
+  }
+
+  inline int TriSign(int64_t x) // returns 0, 1 or -1
+  {
+    return (x > 0) - (x < 0); 
+  }
+
+  struct MultiplyUInt64Result
+  {
+    const uint64_t result = 0;
+    const uint64_t carry = 0;
+
+    bool operator==(const MultiplyUInt64Result& other) const
+    {
+      return result == other.result && carry == other.carry;
+    };
+  };
+
+  inline MultiplyUInt64Result Multiply(uint64_t a, uint64_t b) // #834, #835
+  {
+    const auto lo = [](uint64_t x) { return x & 0xFFFFFFFF; };
+    const auto hi = [](uint64_t x) { return x >> 32; };
+
+    const uint64_t x1 = lo(a) * lo(b);
+    const uint64_t x2 = hi(a) * lo(b) + hi(x1);
+    const uint64_t x3 = lo(a) * hi(b) + lo(x2);
+    const uint64_t result = lo(x3) << 32 | lo(x1);
+    const uint64_t carry = hi(a) * hi(b) + hi(x2) + hi(x3);
+
+    return { result, carry };
+  }
+
+  // returns true if (and only if) a * b == c * d
+  inline bool ProductsAreEqual(int64_t a, int64_t b, int64_t c, int64_t d)
+  {
+// -- GODOT start --
+// #if (defined(__clang__) || defined(__GNUC__)) && UINTPTR_MAX >= UINT64_MAX
+//     const auto ab = static_cast<__int128_t>(a) * static_cast<__int128_t>(b);
+//     const auto cd = static_cast<__int128_t>(c) * static_cast<__int128_t>(d);
+//     return ab == cd;
+// #else
+// -- GODOT end --
+    // nb: unsigned values needed for calculating overflow carry
+    const auto abs_a = static_cast<uint64_t>(std::abs(a));
+    const auto abs_b = static_cast<uint64_t>(std::abs(b));
+    const auto abs_c = static_cast<uint64_t>(std::abs(c));
+    const auto abs_d = static_cast<uint64_t>(std::abs(d));
+
+    const auto abs_ab = Multiply(abs_a, abs_b);
+    const auto abs_cd = Multiply(abs_c, abs_d);
+
+    // nb: it's important to differentiate 0 values here from other values
+    const auto sign_ab = TriSign(a) * TriSign(b);
+    const auto sign_cd = TriSign(c) * TriSign(d);
+
+    return abs_ab == abs_cd && sign_ab == sign_cd;
+// -- GODOT start --
+// #endif
+// -- GODOT end --
+  }
+
+  template <typename T>
+  inline bool IsCollinear(const Point<T>& pt1,
+    const Point<T>& sharedPt, const Point<T>& pt2) // #777
+  {
+    const auto a = sharedPt.x - pt1.x;
+    const auto b = pt2.y - sharedPt.y;
+    const auto c = sharedPt.y - pt1.y;
+    const auto d = pt2.x - sharedPt.x;
+    // When checking for collinearity with very large coordinate values
+    // then ProductsAreEqual is more accurate than using CrossProduct.
+    return ProductsAreEqual(a, b, c, d);
   }
 
+
   template <typename T>
   inline double CrossProduct(const Point<T>& pt1, const Point<T>& pt2, const Point<T>& pt3) {
     return (static_cast<double>(pt2.x - pt1.x) * static_cast<double>(pt3.y -
@@ -635,15 +766,17 @@ namespace Clipper2Lib
   }
 
   template <typename T>
-  inline double DistanceFromLineSqrd(const Point<T>& pt, const Point<T>& ln1, const Point<T>& ln2)
+  inline double PerpendicDistFromLineSqrd(const Point<T>& pt,
+    const Point<T>& line1, const Point<T>& line2)
   {
     //perpendicular distance of point (x³,y³) = (Ax³ + By³ + C)/Sqrt(A² + B²)
     //see http://en.wikipedia.org/wiki/Perpendicular_distance
-    double A = static_cast<double>(ln1.y - ln2.y);
-    double B = static_cast<double>(ln2.x - ln1.x);
-    double C = A * ln1.x + B * ln1.y;
-    C = A * pt.x + B * pt.y - C;
-    return (C * C) / (A * A + B * B);
+    double a = static_cast<double>(pt.x - line1.x);
+    double b = static_cast<double>(pt.y - line1.y);
+    double c = static_cast<double>(line2.x - line1.x);
+    double d = static_cast<double>(line2.y - line1.y);
+    if (c == 0 && d == 0) return 0;
+    return Sqr(a * d - c * b) / (c * c + d * d);
   }
 
   template <typename T>
@@ -663,7 +796,7 @@ namespace Clipper2Lib
     }
     if (cnt & 1)
       a += static_cast<double>(it2->y + it1->y) * (it2->x - it1->x);
-    return a * 0.5;
+    return (a * 0.5);
   }
 
   template <typename T>
@@ -681,16 +814,73 @@ namespace Clipper2Lib
   template <typename T>
   inline bool IsPositive(const Path<T>& poly)
   {
-    // A curve has positive orientation [and area] if a region 'R' 
+    // A curve has positive orientation [and area] if a region 'R'
     // is on the left when traveling around the outside of 'R'.
     //https://mathworld.wolfram.com/CurveOrientation.html
     //nb: This statement is premised on using Cartesian coordinates
     return Area<T>(poly) >= 0;
   }
-  
-  inline bool GetIntersectPoint(const Point64& ln1a, const Point64& ln1b,
-    const Point64& ln2a, const Point64& ln2b, Point64& ip)
-  {  
+
+#if CLIPPER2_HI_PRECISION
+  // caution: this will compromise performance
+  // https://github.com/AngusJohnson/Clipper2/issues/317#issuecomment-1314023253
+  // See also CPP/BenchMark/GetIntersectPtBenchmark.cpp
+  #define CC_MIN(x,y) ((x)>(y)?(y):(x))
+  #define CC_MAX(x,y) ((x)<(y)?(y):(x))
+  template<typename T>
+  inline bool GetSegmentIntersectPt(const Point<T>& ln1a, const Point<T>& ln1b,
+    const Point<T>& ln2a, const Point<T>& ln2b, Point<T>& ip)
+  {
+    double ln1dy = static_cast<double>(ln1b.y - ln1a.y);
+    double ln1dx = static_cast<double>(ln1a.x - ln1b.x);
+    double ln2dy = static_cast<double>(ln2b.y - ln2a.y);
+    double ln2dx = static_cast<double>(ln2a.x - ln2b.x);
+    double det = (ln2dy * ln1dx) - (ln1dy * ln2dx);
+    if (det == 0.0) return false;
+    T bb0minx = CC_MIN(ln1a.x, ln1b.x);
+    T bb0miny = CC_MIN(ln1a.y, ln1b.y);
+    T bb0maxx = CC_MAX(ln1a.x, ln1b.x);
+    T bb0maxy = CC_MAX(ln1a.y, ln1b.y);
+    T bb1minx = CC_MIN(ln2a.x, ln2b.x);
+    T bb1miny = CC_MIN(ln2a.y, ln2b.y);
+    T bb1maxx = CC_MAX(ln2a.x, ln2b.x);
+    T bb1maxy = CC_MAX(ln2a.y, ln2b.y);
+
+    if constexpr (std::is_integral_v<T>)
+    {
+      int64_t originx = (CC_MIN(bb0maxx, bb1maxx) + CC_MAX(bb0minx, bb1minx)) >> 1;
+      int64_t originy = (CC_MIN(bb0maxy, bb1maxy) + CC_MAX(bb0miny, bb1miny)) >> 1;
+      double ln0c = (ln1dy * static_cast<double>(ln1a.x - originx)) +
+        (ln1dx * static_cast<double>(ln1a.y - originy));
+      double ln1c = (ln2dy * static_cast<double>(ln2a.x - originx)) +
+        (ln2dx * static_cast<double>(ln2a.y - originy));
+      double hitx = ((ln1dx * ln1c) - (ln2dx * ln0c)) / det;
+      double hity = ((ln2dy * ln0c) - (ln1dy * ln1c)) / det;
+
+      ip.x = originx + (T)nearbyint(hitx);
+      ip.y = originy + (T)nearbyint(hity);
+    }
+    else
+    {
+      double originx = (CC_MIN(bb0maxx, bb1maxx) + CC_MAX(bb0minx, bb1minx)) / 2.0;
+      double originy = (CC_MIN(bb0maxy, bb1maxy) + CC_MAX(bb0miny, bb1miny)) / 2.0;
+      double ln0c = (ln1dy * static_cast<double>(ln1a.x - originx)) +
+        (ln1dx * static_cast<double>(ln1a.y - originy));
+      double ln1c = (ln2dy * static_cast<double>(ln2a.x - originx)) +
+        (ln2dx * static_cast<double>(ln2a.y - originy));
+      double hitx = ((ln1dx * ln1c) - (ln2dx * ln0c)) / det;
+      double hity = ((ln2dy * ln0c) - (ln1dy * ln1c)) / det;
+
+      ip.x = originx + static_cast<T>(hitx);
+      ip.y = originy + static_cast<T>(hity);
+    }
+    return true;
+}
+#else
+  template<typename T>
+  inline bool GetSegmentIntersectPt(const Point<T>& ln1a, const Point<T>& ln1b,
+    const Point<T>& ln2a, const Point<T>& ln2b, Point<T>& ip)
+  {
     // https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection
     double dx1 = static_cast<double>(ln1b.x - ln1a.x);
     double dy1 = static_cast<double>(ln1b.y - ln1a.y);
@@ -700,15 +890,44 @@ namespace Clipper2Lib
     double det = dy1 * dx2 - dy2 * dx1;
     if (det == 0.0) return false;
     double t = ((ln1a.x - ln2a.x) * dy2 - (ln1a.y - ln2a.y) * dx2) / det;
-    if (t <= 0.0) ip = ln1a;        // ?? check further (see also #568)
-    else if (t >= 1.0) ip = ln1b;   // ?? check further
+    if (t <= 0.0) ip = ln1a;
+    else if (t >= 1.0) ip = ln1b;
     else
     {
-      ip.x = static_cast<int64_t>(ln1a.x + t * dx1);
-      ip.y = static_cast<int64_t>(ln1a.y + t * dy1);
-    }
+      ip.x = static_cast<T>(ln1a.x + t * dx1);
+      ip.y = static_cast<T>(ln1a.y + t * dy1);
+  }
     return true;
   }
+#endif
+
+  template<typename T>
+  inline Point<T> TranslatePoint(const Point<T>& pt, double dx, double dy)
+  {
+#ifdef USINGZ
+    return Point<T>(pt.x + dx, pt.y + dy, pt.z);
+#else
+    return Point<T>(pt.x + dx, pt.y + dy);
+#endif
+  }
+
+
+  template<typename T>
+  inline Point<T> ReflectPoint(const Point<T>& pt, const Point<T>& pivot)
+  {
+#ifdef USINGZ
+    return Point<T>(pivot.x + (pivot.x - pt.x), pivot.y + (pivot.y - pt.y), pt.z);
+#else
+    return Point<T>(pivot.x + (pivot.x - pt.x), pivot.y + (pivot.y - pt.y));
+#endif
+  }
+
+  template<typename T>
+  inline int GetSign(const T& val) 
+  { 
+    if (!val) return 0; 
+    return (val > 0) ? 1 : -1;
+  }
 
   inline bool SegmentsIntersect(const Point64& seg1a, const Point64& seg1b,
     const Point64& seg2a, const Point64& seg2b, bool inclusive = false)
@@ -724,10 +943,10 @@ namespace Clipper2Lib
       return (res1 || res2 || res3 || res4); // ensures not collinear
     }
     else {
-      return (CrossProduct(seg1a, seg2a, seg2b) *
-        CrossProduct(seg1b, seg2a, seg2b) < 0) &&
-        (CrossProduct(seg2a, seg1a, seg1b) *
-          CrossProduct(seg2b, seg1a, seg1b) < 0);
+      return (GetSign(CrossProduct(seg1a, seg2a, seg2b)) *
+        GetSign(CrossProduct(seg1b, seg2a, seg2b)) < 0) &&
+        (GetSign(CrossProduct(seg2a, seg1a, seg1b)) *
+          GetSign(CrossProduct(seg2b, seg1a, seg1b)) < 0);
     }
   }
 
@@ -743,7 +962,7 @@ namespace Clipper2Lib
         static_cast<double>(offPt.y - seg1.y) * dy) /
       (Sqr(dx) + Sqr(dy));
     if (q < 0) q = 0; else if (q > 1) q = 1;
-    if constexpr (std::numeric_limits<T>::is_integer)
+    if constexpr (std::is_integral_v<T>)
       return Point<T>(
         seg1.x + static_cast<T>(nearbyint(q * dx)),
         seg1.y + static_cast<T>(nearbyint(q * dy)));
@@ -770,7 +989,7 @@ namespace Clipper2Lib
       return PointInPolygonResult::IsOutside;
 
     bool is_above = first->y < pt.y, starting_above = is_above;
-    curr = first +1; 
+    curr = first +1;
     while (true)
     {
       if (curr == cend)
@@ -779,7 +998,7 @@ namespace Clipper2Lib
         cend = first;
         curr = cbegin;
       }
-      
+
       if (is_above)
       {
         while (curr != cend && curr->y < pt.y) ++curr;
@@ -791,14 +1010,14 @@ namespace Clipper2Lib
         if (curr == cend) continue;
       }
 
-      if (curr == cbegin) 
+      if (curr == cbegin)
         prev = polygon.cend() - 1; //nb: NOT cend (since might equal first)
-      else  
+      else
         prev = curr - 1;
 
       if (curr->y == pt.y)
       {
-        if (curr->x == pt.x || 
+        if (curr->x == pt.x ||
           (curr->y == prev->y &&
             ((pt.x < prev->x) != (pt.x < curr->x))))
               return PointInPolygonResult::IsOn;
@@ -822,7 +1041,7 @@ namespace Clipper2Lib
       is_above = !is_above;
       ++curr;
     }
-    
+
     if (is_above != starting_above)
     {
       cend = polygon.cend();

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

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  22 November 2023                                                *
+* Date      :  5 July 2024                                                     *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  This is the main polygon clipping module                        *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -33,7 +33,7 @@ namespace Clipper2Lib {
 
 	//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 };
 
@@ -41,7 +41,7 @@ namespace Clipper2Lib {
 		None = 0, OpenStart = 1, OpenEnd = 2, LocalMax = 4, LocalMin = 8
 	};
 
-	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));
 	}
@@ -95,7 +95,7 @@ namespace Clipper2Lib {
 		Path64 path;
 		bool is_open = false;
 
-		~OutRec() { 
+		~OutRec() {
 			if (splits) delete splits;
 			// nb: don't delete the split pointers
 			// as these are owned by ClipperBase's outrec_list_
@@ -106,7 +106,7 @@ namespace Clipper2Lib {
 	//Important: UP and DOWN here are premised on Y-axis positive down
 	//displays, which is the orientation used in Clipper's development.
 	///////////////////////////////////////////////////////////////////
-	
+
 	struct Active {
 		Point64 bot;
 		Point64 top;
@@ -230,7 +230,7 @@ namespace Clipper2Lib {
 		inline bool PopHorz(Active *&e);
 		inline OutPt* StartOpenPath(Active &e, const Point64& pt);
 		inline void UpdateEdgeIntoAEL(Active *e);
-		OutPt* IntersectEdges(Active &e1, Active &e2, const Point64& pt);
+		void IntersectEdges(Active &e1, Active &e2, const Point64& pt);
 		inline void DeleteFromAEL(Active &e);
 		inline void AdjustCurrXAndCopyToSEL(const int64_t top_y);
 		void DoIntersections(const int64_t top_y);
@@ -240,7 +240,7 @@ namespace Clipper2Lib {
 		void SwapPositionsInAEL(Active& edge1, Active& edge2);
 		OutRec* NewOutRec();
 		OutPt* AddOutPt(const Active &e, const Point64& pt);
-		OutPt* AddLocalMinPoly(Active &e1, Active &e2, 
+		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);
@@ -251,13 +251,13 @@ namespace Clipper2Lib {
 		void JoinOutrecPaths(Active &e1, Active &e2);
 		void FixSelfIntersects(OutRec* outrec);
 		void DoSplitOp(OutRec* outRec, OutPt* splitOp);
-		
+
 		inline void AddTrialHorzJoin(OutPt* op);
 		void ConvertHorzSegsToJoins();
 		void ProcessHorzJoins();
 
 		void Split(Active& e, const Point64& pt);
-		inline void CheckJoinLeft(Active& e, 
+		inline void CheckJoinLeft(Active& e,
 			const Point64& pt, bool check_curr_x = false);
 		inline void CheckJoinRight(Active& e,
 			const Point64& pt, bool check_curr_x = false);
@@ -326,12 +326,12 @@ namespace Clipper2Lib {
 
 		const PolyPath* Parent() const { return parent_; }
 
-		bool IsHole() const 
+		bool IsHole() const
 		{
 			unsigned lvl = Level();
 			//Even levels except level 0
 			return lvl && !(lvl & 1);
-		}		
+		}
 	};
 
 	typedef typename std::vector<std::unique_ptr<PolyPath64>> PolyPath64List;
@@ -343,15 +343,16 @@ namespace Clipper2Lib {
 		Path64 polygon_;
 	public:
 		explicit PolyPath64(PolyPath64* parent = nullptr) : PolyPath(parent) {}
+		explicit PolyPath64(PolyPath64* parent, const Path64& path) : PolyPath(parent) { polygon_ = path; }
 
 		~PolyPath64() {
 			childs_.resize(0);
 		}
 
 		PolyPath64* operator [] (size_t index) const
-		{ 
+		{
 			return childs_[index].get(); //std::unique_ptr
-		} 
+		}
 
 		PolyPath64* Child(size_t index) const
 		{
@@ -363,10 +364,7 @@ namespace Clipper2Lib {
 
 		PolyPath64* AddChild(const Path64& path) override
 		{
-			auto p = std::make_unique<PolyPath64>(this);
-			auto* result = childs_.emplace_back(std::move(p)).get();
-			result->polygon_ = path;
-			return result;
+			return childs_.emplace_back(std::make_unique<PolyPath64>(this, path)).get();
 		}
 
 		void Clear() override
@@ -401,12 +399,25 @@ namespace Clipper2Lib {
 			scale_ = parent ? parent->scale_ : 1.0;
 		}
 
+		explicit PolyPathD(PolyPathD* parent, const Path64& path) : PolyPath(parent)
+		{
+			scale_ = parent ? parent->scale_ : 1.0;
+			int error_code = 0;
+			polygon_ = ScalePath<double, int64_t>(path, scale_, error_code);
+		}
+
+		explicit PolyPathD(PolyPathD* parent, const PathD& path) : PolyPath(parent)
+		{
+			scale_ = parent ? parent->scale_ : 1.0;
+			polygon_ = path;
+		}
+
 		~PolyPathD() {
 			childs_.resize(0);
 		}
 
 		PolyPathD* operator [] (size_t index) const
-		{ 
+		{
 			return childs_[index].get();
 		}
 
@@ -420,22 +431,15 @@ namespace Clipper2Lib {
 
 		void SetScale(double value) { scale_ = value; }
 		double Scale() const { return scale_; }
-		
+
 		PolyPathD* AddChild(const Path64& path) override
 		{
-			int error_code = 0;
-			auto p = std::make_unique<PolyPathD>(this);
-			PolyPathD* result = childs_.emplace_back(std::move(p)).get();
-			result->polygon_ = ScalePath<double, int64_t>(path, scale_, error_code);
-			return result;
+			return childs_.emplace_back(std::make_unique<PolyPathD>(this, path)).get();
 		}
 
 		PolyPathD* AddChild(const PathD& path)
 		{
-			auto p = std::make_unique<PolyPathD>(this);
-			PolyPathD* result = childs_.emplace_back(std::move(p)).get();
-			result->polygon_ = path;
-			return result;
+			return childs_.emplace_back(std::make_unique<PolyPathD>(this, path)).get();
 		}
 
 		void Clear() override
@@ -488,7 +492,7 @@ namespace Clipper2Lib {
 			return Execute(clip_type, fill_rule, closed_paths, dummy);
 		}
 
-		bool Execute(ClipType clip_type, FillRule fill_rule, 
+		bool Execute(ClipType clip_type, FillRule fill_rule,
 			Paths64& closed_paths, Paths64& open_paths)
 		{
 			closed_paths.clear();
@@ -530,7 +534,7 @@ namespace Clipper2Lib {
 	public:
 		explicit ClipperD(int precision = 2) : ClipperBase()
 		{
-			CheckPrecision(precision, error_code_);
+			CheckPrecisionRange(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,
@@ -560,12 +564,12 @@ namespace Clipper2Lib {
 		void CheckCallback()
 		{
 			if(zCallbackD_)
-				// if the user defined float point callback has been assigned 
+				// if the user defined float point callback has been assigned
 				// then assign the proxy callback function
-				ClipperBase::zCallback_ = 
+				ClipperBase::zCallback_ =
 					std::bind(&ClipperD::ZCB, this, std::placeholders::_1,
 					std::placeholders::_2, std::placeholders::_3,
-					std::placeholders::_4, std::placeholders::_5); 
+					std::placeholders::_4, std::placeholders::_5);
 			else
 				ClipperBase::zCallback_ = nullptr;
 		}
@@ -632,6 +636,6 @@ namespace Clipper2Lib {
 
 	};
 
-}  // namespace 
+}  // namespace
 
 #endif  // CLIPPER_ENGINE_H

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

@@ -1,14 +1,14 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  26 November 2023                                                *
+* Date      :  14 May 2024                                                     *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  This module exports the Clipper2 Library (ie DLL/so)            *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
 
 
-/* 
+/*
  Boolean clipping:
  cliptype: None=0, Intersection=1, Union=2, Difference=3, Xor=4
  fillrule: EvenOdd=0, NonZero=1, Positive=2, Negative=3
@@ -19,12 +19,12 @@
 
 The path structures used extensively in other parts of this library are all
 based on std::vector classes. Since C++ classes can't be accessed by other
-languages, these paths must be converted into simple C data structures that
-can be understood by just about any programming language. And these C style
-path structures are simple arrays of int64_t (CPath64) and double (CPathD).
+languages, these paths are converted into very simple array data structures 
+(of either int64_t for CPath64 or double for CPathD) that can be parsed by 
+just about any programming language.
 
 CPath64 and CPathD:
-These are arrays of consecutive x and y path coordinates preceeded by  
+These are arrays of consecutive x and y path coordinates preceeded by
 a pair of values containing the path's length (N) and a 0 value.
 __________________________________
 |counter|coord1|coord2|...|coordN|
@@ -34,23 +34,24 @@ __________________________________
 CPaths64 and CPathsD:
 These are also arrays containing any number of consecutive CPath64 or
 CPathD  structures. But preceeding these consecutive paths, there is pair of
-values that contain the total length of the array (A) structure and 
-the number (C) of CPath64 or CPathD it contains.
+values that contain the total length of the array structure (A) and the 
+number of CPath64 or CPathD it contains (C). The space these structures will
+occupy in memory = A * sizeof(int64_t) or  A * sizeof(double) respectively. 
 _______________________________
 |counter|path1|path2|...|pathC|
 |A  , C |                     |
 _______________________________
 
 CPolytree64 and CPolytreeD:
-These are also arrays consisting of CPolyPath structures that represent 
+These are also arrays consisting of CPolyPath structures that represent
 individual paths in a tree structure. However, the very first (ie top)
-CPolyPath is just the tree container that won't have a path. And because
+CPolyPath is just the tree container that doesn't have a path. And because
 of that, its structure will be very slightly different from the remaining
 CPolyPath. This difference will be discussed below.
 
 CPolyPath64 and CPolyPathD:
-These are simple arrays consisting of a series of path coordinates followed 
-by any number of child (ie nested) CPolyPath. Preceeding these are two values 
+These are simple arrays consisting of a series of path coordinates followed
+by any number of child (ie nested) CPolyPath. Preceeding these are two values
 indicating the length of the path (N) and the number of child CPolyPath (C).
 ____________________________________________________________
 |counter|coord1|coord2|...|coordN| child1|child2|...|childC|
@@ -58,19 +59,20 @@ ____________________________________________________________
 ____________________________________________________________
 
 As mentioned above, the very first CPolyPath structure is just a container
-that owns (both directly and indirectly) every other CPolyPath in the tree. 
+that owns (both directly and indirectly) every other CPolyPath in the tree.
 Since this first CPolyPath has no path, instead of a path length, its very
-first value will contain the total length of the CPolytree array structure.
-
-All theses exported structures (CPaths64, CPathsD, CPolyTree64 & CPolyTreeD)
-are arrays of type int64_t or double. And the first value in these arrays 
-will always contain the length of that array.
-
-These array structures are allocated in heap memory which will eventually 
-need to be released. But since applications dynamically linking to these 
-functions may use different memory managers, the only safe way to free up
-this memory is to use the exported DisposeArray64 and  DisposeArrayD 
-functions below.
+first value will contain the total length of the CPolytree array (not its
+total bytes length).
+
+Again, all theses exported structures (CPaths64, CPathsD, CPolyTree64 & 
+CPolyTreeD) are arrays of either type int64_t or double, and the first 
+value in these arrays will always be the length of that array.
+
+These array structures are allocated in heap memory which will eventually
+need to be released. However, since applications dynamically linking to 
+these functions may use different memory managers, the only safe way to 
+free up this memory is to use the exported DisposeArray64 and 
+DisposeArrayD functions (see below).
 */
 
 
@@ -128,7 +130,7 @@ inline Rect<T> CRectToRect(const CRect<T>& rect)
 #ifdef _WIN32
   #define EXTERN_DLL_EXPORT extern "C" __declspec(dllexport)
 #else
-  #define EXTERN_DLL_EXPORT extern "C" 
+  #define EXTERN_DLL_EXPORT extern "C"
 #endif
 
 
@@ -173,8 +175,8 @@ EXTERN_DLL_EXPORT int BooleanOp_PolyTreeD(uint8_t cliptype,
   bool preserve_collinear = true, bool reverse_solution = false);
 
 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, 
+  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,
@@ -219,10 +221,10 @@ static size_t GetPolyPath64ArrayLen(const PolyPath64& pp)
   return result;
 }
 
-static void GetPolytreeCountAndCStorageSize(const PolyTree64& tree, 
+static void GetPolytreeCountAndCStorageSize(const PolyTree64& tree,
   size_t& cnt, size_t& array_len)
 {
-  cnt = tree.Count(); // nb: top level count only 
+  cnt = tree.Count(); // nb: top level count only
   array_len = GetPolyPath64ArrayLen(tree);
 }
 
@@ -271,17 +273,34 @@ CPathsD CreateCPathsDFromPaths64(const Paths64& paths, double scale)
   return result;
 }
 
+template <typename T>
+static Path<T> ConvertCPath(T* path)
+{
+  Path<T> result;
+  if (!path) return result;
+  T* v = path;
+  size_t cnt = static_cast<size_t>(*v);
+  v += 2; // skip 0 value
+  result.reserve(cnt);
+  for (size_t j = 0; j < cnt; ++j)
+  {
+    T x = *v++, y = *v++;
+    result.push_back(Point<T>(x, y));
+  }
+  return result;
+}
+
 template <typename T>
 static Paths<T> ConvertCPaths(T* paths)
 {
   Paths<T> result;
   if (!paths) return result;
   T* v = paths; ++v;
-  size_t cnt = *v++;
+  size_t cnt = static_cast<size_t>(*v++);
   result.reserve(cnt);
   for (size_t i = 0; i < cnt; ++i)
   {
-    size_t cnt2 = *v;
+    size_t cnt2 = static_cast<size_t>(*v);
     v += 2;
     Path<T> path;
     path.reserve(cnt2);
@@ -300,17 +319,17 @@ static Paths64 ConvertCPathsDToPaths64(const CPathsD paths, double scale)
 {
   Paths64 result;
   if (!paths) return result;
-  double* v = paths; 
+  double* v = paths;
   ++v; // skip the first value (0)
-  int64_t cnt = (int64_t)*v++;
+  size_t cnt = static_cast<size_t>(*v++);
   result.reserve(cnt);
-  for (int i = 0; i < cnt; ++i)
+  for (size_t i = 0; i < cnt; ++i)
   {
-    int64_t cnt2 = (int64_t)*v;
+    size_t cnt2 = static_cast<size_t>(*v);
     v += 2;
     Path64 path;
     path.reserve(cnt2);
-    for (int j = 0; j < cnt2; ++j)
+    for (size_t j = 0; j < cnt2; ++j)
     {
       double x = *v++ * scale;
       double y = *v++ * scale;
@@ -362,7 +381,7 @@ EXTERN_DLL_EXPORT const char* Version()
   return CLIPPER2_VERSION;
 }
 
-EXTERN_DLL_EXPORT int BooleanOp64(uint8_t cliptype, 
+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,
@@ -370,7 +389,7 @@ EXTERN_DLL_EXPORT int BooleanOp64(uint8_t cliptype,
 {
   if (cliptype > static_cast<uint8_t>(ClipType::Xor)) return -4;
   if (fillrule > static_cast<uint8_t>(FillRule::Negative)) return -3;
-  
+
   Paths64 sub, sub_open, clp, sol, sol_open;
   sub       = ConvertCPaths(subjects);
   sub_open  = ConvertCPaths(subjects_open);
@@ -382,7 +401,7 @@ EXTERN_DLL_EXPORT int BooleanOp64(uint8_t cliptype,
   if (sub.size() > 0) clipper.AddSubject(sub);
   if (sub_open.size() > 0) clipper.AddOpenSubject(sub_open);
   if (clp.size() > 0) clipper.AddClip(clp);
-  if (!clipper.Execute(ClipType(cliptype), FillRule(fillrule), sol, sol_open)) 
+  if (!clipper.Execute(ClipType(cliptype), FillRule(fillrule), sol, sol_open))
     return -1; // clipping bug - should never happen :)
   solution = CreateCPaths(sol);
   solution_open = CreateCPaths(sol_open);
@@ -455,7 +474,7 @@ EXTERN_DLL_EXPORT int BooleanOp_PolyTreeD(uint8_t cliptype,
   if (precision < -8 || precision > 8) return -5;
   if (cliptype > static_cast<uint8_t>(ClipType::Xor)) return -4;
   if (fillrule > static_cast<uint8_t>(FillRule::Negative)) return -3;
-  
+
   double scale = std::pow(10, precision);
 
   int err = 0;
@@ -485,10 +504,10 @@ EXTERN_DLL_EXPORT CPaths64 InflatePaths64(const CPaths64 paths,
 {
   Paths64 pp;
   pp = ConvertCPaths(paths);
-  ClipperOffset clip_offset( miter_limit, 
+  ClipperOffset clip_offset( miter_limit,
     arc_tolerance, reverse_solution);
   clip_offset.AddPaths(pp, JoinType(jointype), EndType(endtype));
-  Paths64 result; 
+  Paths64 result;
   clip_offset.Execute(delta, result);
   return CreateCPaths(result);
 }
@@ -560,6 +579,22 @@ EXTERN_DLL_EXPORT CPathsD RectClipLinesD(const CRectD& rect,
   return CreateCPathsDFromPaths64(result, 1 / scale);
 }
 
+EXTERN_DLL_EXPORT CPaths64 MinkowskiSum64(const CPath64& cpattern, const CPath64& cpath, bool is_closed)
+{
+  Path64 path = ConvertCPath(cpath);
+  Path64 pattern = ConvertCPath(cpattern);
+  Paths64 solution = MinkowskiSum(pattern, path, is_closed);
+  return CreateCPaths(solution);
+}
+
+EXTERN_DLL_EXPORT CPaths64 MinkowskiDiff64(const CPath64& cpattern, const CPath64& cpath, bool is_closed)
+{
+  Path64 path = ConvertCPath(cpath);
+  Path64 pattern = ConvertCPath(cpattern);
+  Paths64 solution = MinkowskiDiff(pattern, path, is_closed);
+  return CreateCPaths(solution);
+}
+
 }  // end Clipper2Lib namespace
-  
+
 #endif  // CLIPPER2_EXPORT_H

thirdparty/clipper2/include/clipper2/clipper.h

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  18 November 2023                                                *
+* Date      :  27 April 2024                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  This module provides a simple interface to the Clipper Library  *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -24,7 +24,7 @@ namespace Clipper2Lib {
 
   inline Paths64 BooleanOp(ClipType cliptype, FillRule fillrule,
     const Paths64& subjects, const Paths64& clips)
-  {    
+  {
     Paths64 result;
     Clipper64 clipper;
     clipper.AddSubject(subjects);
@@ -47,7 +47,7 @@ namespace Clipper2Lib {
     const PathsD& subjects, const PathsD& clips, int precision = 2)
   {
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     PathsD result;
     if (error_code) return result;
     ClipperD clipper(precision);
@@ -58,12 +58,12 @@ namespace Clipper2Lib {
   }
 
   inline void BooleanOp(ClipType cliptype, FillRule fillrule,
-    const PathsD& subjects, const PathsD& clips, 
+    const PathsD& subjects, const PathsD& clips,
     PolyTreeD& polytree, int precision = 2)
   {
     polytree.Clear();
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     if (error_code) return;
     ClipperD clipper(precision);
     clipper.AddSubject(subjects);
@@ -75,7 +75,7 @@ namespace Clipper2Lib {
   {
     return BooleanOp(ClipType::Intersection, fillrule, subjects, clips);
   }
-  
+
   inline PathsD Intersect(const PathsD& subjects, const PathsD& clips, FillRule fillrule, int decimal_prec = 2)
   {
     return BooleanOp(ClipType::Intersection, fillrule, subjects, clips, decimal_prec);
@@ -104,7 +104,7 @@ namespace Clipper2Lib {
   {
     PathsD result;
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     if (error_code) return result;
     ClipperD clipper(precision);
     clipper.AddSubject(subjects);
@@ -145,11 +145,11 @@ namespace Clipper2Lib {
   }
 
   inline PathsD InflatePaths(const PathsD& paths, double delta,
-    JoinType jt, EndType et, double miter_limit = 2.0, 
+    JoinType jt, EndType et, double miter_limit = 2.0,
     int precision = 2, double arc_tolerance = 0.0)
   {
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     if (!delta) return paths;
     if (error_code) return PathsD();
     const double scale = std::pow(10, precision);
@@ -219,13 +219,13 @@ namespace Clipper2Lib {
   {
     if (rect.IsEmpty() || paths.empty()) return PathsD();
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     if (error_code) return PathsD();
     const double scale = std::pow(10, precision);
     Rect64 r = ScaleRect<int64_t, double>(rect, scale);
     RectClip64 rc(r);
     Paths64 pp = ScalePaths<int64_t, double>(paths, scale, error_code);
-    if (error_code) return PathsD(); // ie: error_code result is lost 
+    if (error_code) return PathsD(); // ie: error_code result is lost
     return ScalePaths<double, int64_t>(
       rc.Execute(pp), 1 / scale, error_code);
   }
@@ -251,7 +251,7 @@ namespace Clipper2Lib {
   {
     if (rect.IsEmpty() || lines.empty()) return PathsD();
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     if (error_code) return PathsD();
     const double scale = std::pow(10, precision);
     Rect64 r = ScaleRect<int64_t, double>(rect, scale);
@@ -290,8 +290,8 @@ namespace Clipper2Lib {
       {
         // return false if this child isn't fully contained by its parent
 
-        // checking for a single vertex outside is a bit too crude since 
-        // it doesn't account for rounding errors. It's better to check 
+        // checking for a single vertex outside is a bit too crude since
+        // it doesn't account for rounding errors. It's better to check
         // for consecutive vertices found outside the parent's polygon.
 
         int outsideCnt = 0;
@@ -311,7 +311,7 @@ namespace Clipper2Lib {
       return true;
     }
 
-    static void OutlinePolyPath(std::ostream& os, 
+    static void OutlinePolyPath(std::ostream& os,
       size_t idx, bool isHole, size_t count, const std::string& preamble)
     {
       std::string plural = (count == 1) ? "." : "s.";
@@ -342,19 +342,19 @@ namespace Clipper2Lib {
     }
 
     template<typename T, typename U>
-    inline constexpr void MakePathGeneric(const T an_array, 
+    inline constexpr void MakePathGeneric(const T an_array,
       size_t array_size, std::vector<U>& result)
     {
       result.reserve(array_size / 2);
       for (size_t i = 0; i < array_size; i +=2)
 #ifdef USINGZ
-        result.push_back( U{ an_array[i], an_array[i +1], 0} );
+        result.push_back( U{ an_array[i], an_array[i + 1], 0} );
 #else
         result.push_back( U{ an_array[i], an_array[i + 1]} );
 #endif
     }
 
-  } // end details namespace 
+  } // end details namespace
 
   inline std::ostream& operator<< (std::ostream& os, const PolyTree64& pp)
   {
@@ -398,7 +398,7 @@ namespace Clipper2Lib {
   inline bool CheckPolytreeFullyContainsChildren(const PolyTree64& polytree)
   {
     for (const auto& child : polytree)
-      if (child->Count() > 0 && 
+      if (child->Count() > 0 &&
         !details::PolyPath64ContainsChildren(*child))
           return false;
     return true;
@@ -471,7 +471,7 @@ namespace Clipper2Lib {
     std::size_t size = N / 3;
     Path64 result(size);
     for (size_t i = 0; i < size; ++i)
-      result[i] = Point64(list[i * 3], 
+      result[i] = Point64(list[i * 3],
         list[i * 3 + 1], list[i * 3 + 2]);
     return result;
   }
@@ -489,7 +489,7 @@ namespace Clipper2Lib {
           list[i * 3 + 1], list[i * 3 + 2]);
     else
       for (size_t i = 0; i < size; ++i)
-        result[i] = PointD(list[i * 3], list[i * 3 + 1], 
+        result[i] = PointD(list[i * 3], list[i * 3 + 1],
           static_cast<int64_t>(list[i * 3 + 2]));
     return result;
   }
@@ -510,9 +510,9 @@ namespace Clipper2Lib {
 
     if (!is_open_path)
     {
-      while (srcIt != stop && !CrossProduct(*stop, *srcIt, *(srcIt + 1)))
+      while (srcIt != stop && IsCollinear(*stop, *srcIt, *(srcIt + 1)))
         ++srcIt;
-      while (srcIt != stop && !CrossProduct(*(stop - 1), *stop, *srcIt))
+      while (srcIt != stop && IsCollinear(*(stop - 1), *stop, *srcIt))
         --stop;
       if (srcIt == stop) return Path64();
     }
@@ -521,7 +521,7 @@ namespace Clipper2Lib {
     dst.push_back(*prevIt);
     for (; srcIt != stop; ++srcIt)
     {
-      if (CrossProduct(*prevIt, *srcIt, *(srcIt + 1)))
+      if (!IsCollinear(*prevIt, *srcIt, *(srcIt + 1)))
       {
         prevIt = srcIt;
         dst.push_back(*prevIt);
@@ -530,12 +530,12 @@ namespace Clipper2Lib {
 
     if (is_open_path)
       dst.push_back(*srcIt);
-    else if (CrossProduct(*prevIt, *stop, dst[0]))
+    else if (!IsCollinear(*prevIt, *stop, dst[0]))
       dst.push_back(*stop);
     else
     {
       while (dst.size() > 2 &&
-        !CrossProduct(dst[dst.size() - 1], dst[dst.size() - 2], dst[0]))
+        IsCollinear(dst[dst.size() - 1], dst[dst.size() - 2], dst[0]))
           dst.pop_back();
       if (dst.size() < 3) return Path64();
     }
@@ -545,7 +545,7 @@ namespace Clipper2Lib {
   inline PathD TrimCollinear(const PathD& path, int precision, bool is_open_path = false)
   {
     int error_code = 0;
-    CheckPrecision(precision, error_code);
+    CheckPrecisionRange(precision, error_code);
     if (error_code) return PathD();
     const double scale = std::pow(10, precision);
     Path64 p = ScalePath<int64_t, double>(path, scale, error_code);
@@ -580,23 +580,23 @@ namespace Clipper2Lib {
     double cp = std::abs(CrossProduct(pt1, pt2, pt3));
     return (cp * cp) / (DistanceSqr(pt1, pt2) * DistanceSqr(pt2, pt3)) < sin_sqrd_min_angle_rads;
   }
-  
+
   template <typename T>
-  inline Path<T> Ellipse(const Rect<T>& rect, int steps = 0)
+  inline Path<T> Ellipse(const Rect<T>& rect, size_t steps = 0)
   {
-    return Ellipse(rect.MidPoint(), 
-      static_cast<double>(rect.Width()) *0.5, 
+    return Ellipse(rect.MidPoint(),
+      static_cast<double>(rect.Width()) *0.5,
       static_cast<double>(rect.Height()) * 0.5, steps);
   }
 
   template <typename T>
   inline Path<T> Ellipse(const Point<T>& center,
-    double radiusX, double radiusY = 0, int steps = 0)
+    double radiusX, double radiusY = 0, size_t steps = 0)
   {
     if (radiusX <= 0) return Path<T>();
     if (radiusY <= 0) radiusY = radiusX;
     if (steps <= 2)
-      steps = static_cast<int>(PI * sqrt((radiusX + radiusY) / 2));
+      steps = static_cast<size_t>(PI * sqrt((radiusX + radiusY) / 2));
 
     double si = std::sin(2 * PI / steps);
     double co = std::cos(2 * PI / steps);
@@ -604,7 +604,7 @@ namespace Clipper2Lib {
     Path<T> result;
     result.reserve(steps);
     result.push_back(Point<T>(center.x + radiusX, static_cast<double>(center.y)));
-    for (int i = 1; i < steps; ++i)
+    for (size_t i = 1; i < steps; ++i)
     {
       result.push_back(Point<T>(center.x + radiusX * dx, center.y + radiusY * dy));
       double x = dx * co - dy * si;
@@ -614,19 +614,7 @@ namespace Clipper2Lib {
     return result;
   }
 
-  template <typename T>
-  inline double PerpendicDistFromLineSqrd(const Point<T>& pt,
-    const Point<T>& line1, const Point<T>& line2)
-  {
-    double a = static_cast<double>(pt.x - line1.x);
-    double b = static_cast<double>(pt.y - line1.y);
-    double c = static_cast<double>(line2.x - line1.x);
-    double d = static_cast<double>(line2.y - line1.y);
-    if (c == 0 && d == 0) return 0;
-    return Sqr(a * d - c * b) / (c * c + d * d);
-  }
-
-  inline size_t GetNext(size_t current, size_t high, 
+  inline size_t GetNext(size_t current, size_t high,
     const std::vector<bool>& flags)
   {
     ++current;
@@ -637,7 +625,7 @@ namespace Clipper2Lib {
     return current;
   }
 
-  inline size_t GetPrior(size_t current, size_t high, 
+  inline size_t GetPrior(size_t current, size_t high,
     const std::vector<bool>& flags)
   {
     if (current == 0) current = high;
@@ -650,7 +638,7 @@ namespace Clipper2Lib {
   }
 
   template <typename T>
-  inline Path<T> SimplifyPath(const Path<T> &path, 
+  inline Path<T> SimplifyPath(const Path<T> &path,
     double epsilon, bool isClosedPath = true)
   {
     const size_t len = path.size(), high = len -1;
@@ -665,7 +653,7 @@ namespace Clipper2Lib {
       distSqr[0] = PerpendicDistFromLineSqrd(path[0], path[high], path[1]);
       distSqr[high] = PerpendicDistFromLineSqrd(path[high], path[0], path[high - 1]);
     }
-    else 
+    else
     {
       distSqr[0] = MAX_DBL;
       distSqr[high] = MAX_DBL;
@@ -684,7 +672,7 @@ namespace Clipper2Lib {
         } while (curr != start && distSqr[curr] > epsSqr);
         if (curr == start) break;
       }
-      
+
       prior = GetPrior(curr, high, flags);
       next = GetNext(curr, high, flags);
       if (next == prior) break;
@@ -699,7 +687,7 @@ namespace Clipper2Lib {
       }
       else
         prior2 = GetPrior(prior, high, flags);
-        
+
       flags[curr] = true;
       curr = next;
       next = GetNext(next, high, flags);
@@ -717,7 +705,7 @@ namespace Clipper2Lib {
   }
 
   template <typename T>
-  inline Paths<T> SimplifyPaths(const Paths<T> &paths, 
+  inline Paths<T> SimplifyPaths(const Paths<T> &paths,
     double epsilon, bool isClosedPath = true)
   {
     Paths<T> result;

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

@@ -15,7 +15,7 @@
 #include <string>
 #include "clipper2/clipper.core.h"
 
-namespace Clipper2Lib 
+namespace Clipper2Lib
 {
 
   namespace detail

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

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  19 November 2023                                                *
+* Date      :  24 March 2024                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -34,9 +34,7 @@ private:
 	class Group {
 	public:
 		Paths64 paths_in;
-		std::vector<bool> is_hole_list;
-		std::vector<Rect64> bounds_list;
-		int lowest_path_idx = -1;
+        std::optional<size_t> lowest_path_idx{};
 		bool is_reversed = false;
 		JoinType join_type;
 		EndType end_type;
@@ -52,7 +50,8 @@ private:
 	double step_cos_ = 0.0;
 	PathD norms;
 	Path64 path_out;
-	Paths64 solution;
+	Paths64* solution = nullptr;
+	PolyTree64* solution_tree = nullptr;
 	std::vector<Group> groups_;
 	JoinType join_type_ = JoinType::Bevel;
 	EndType end_type_ = EndType::Polygon;
@@ -64,9 +63,10 @@ private:
 
 #ifdef USINGZ
 	ZCallback64 zCallback64_ = nullptr;
+	void ZCB(const Point64& bot1, const Point64& top1,
+		const Point64& bot2, const Point64& top2, Point64& ip);
 #endif
 	DeltaCallback64 deltaCallback64_ = nullptr;
-
 	size_t CalcSolutionCapacity();
 	bool CheckReverseOrientation();
 	void DoBevel(const Path64& path, size_t j, size_t k);
@@ -83,7 +83,7 @@ private:
 public:
 	explicit ClipperOffset(double miter_limit = 2.0,
 		double arc_tolerance = 0.0,
-		bool preserve_collinear = false, 
+		bool preserve_collinear = false,
 		bool reverse_solution = false) :
 		miter_limit_(miter_limit), arc_tolerance_(arc_tolerance),
 		preserve_collinear_(preserve_collinear),
@@ -91,7 +91,7 @@ public:
 
 	~ClipperOffset() { Clear(); };
 
-	int ErrorCode() { return error_code_; };
+	int ErrorCode() const { return error_code_; };
 	void AddPath(const Path64& path, JoinType jt_, EndType et_);
 	void AddPaths(const Paths64& paths, JoinType jt_, EndType et_);
 	void Clear() { groups_.clear(); norms.clear(); };

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

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  1 November 2023                                                 *
+* Date      :  5 July 2024                                                     *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  FAST rectangular clipping                                       *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -18,6 +18,7 @@
 namespace Clipper2Lib
 {
 
+  // Location: the order is important here, see StartLocsIsClockwise()
   enum class Location { Left, Top, Right, Bottom, Inside };
 
   class OutPt2;
@@ -26,10 +27,10 @@ namespace Clipper2Lib
   class OutPt2 {
   public:
     Point64 pt;
-    size_t owner_idx;
-    OutPt2List* edge;
-    OutPt2* next;
-    OutPt2* prev;
+    size_t owner_idx = 0;
+    OutPt2List* edge = nullptr;
+    OutPt2* next = nullptr;
+    OutPt2* prev = nullptr;
   };
 
   //------------------------------------------------------------------------------
@@ -50,9 +51,9 @@ namespace Clipper2Lib
     OutPt2List edges_[8]; // clockwise and counter-clockwise
     std::vector<Location> start_locs_;
     void CheckEdges();
-    void TidyEdges(int idx, OutPt2List& cw, OutPt2List& ccw);
+    void TidyEdges(size_t idx, OutPt2List& cw, OutPt2List& ccw);
     void GetNextLocation(const Path64& path,
-      Location& loc, int& i, int highI);
+      Location& loc, size_t& i, size_t highI);
     OutPt2* Add(Point64 pt, bool start_new = false);
     void AddCorner(Location prev, Location curr);
     void AddCorner(Location& loc, bool isClockwise);

thirdparty/clipper2/include/clipper2/clipper.version.h

@@ -1,6 +1,6 @@
 #ifndef CLIPPER_VERSION_H
 #define CLIPPER_VERSION_H
 
-constexpr auto CLIPPER2_VERSION = "1.3.0";
+constexpr auto CLIPPER2_VERSION = "1.4.0";
 
 #endif  // CLIPPER_VERSION_H

thirdparty/clipper2/patches/clipper2-exceptions.patch

@@ -1,9 +1,9 @@
 diff --git a/thirdparty/clipper2/include/clipper2/clipper.core.h b/thirdparty/clipper2/include/clipper2/clipper.core.h
-index b3dddeeaa2..a77cdad5f4 100644
+index 925c04685e..d0d159b949 100644
 --- a/thirdparty/clipper2/include/clipper2/clipper.core.h
 +++ b/thirdparty/clipper2/include/clipper2/clipper.core.h
-@@ -21,6 +21,8 @@
- #include <numeric>
+@@ -22,6 +22,8 @@
+ #include <optional>
  #include "clipper2/clipper.version.h"
  
 +#define CLIPPER2_THROW(exception) std::abort()
@@ -11,7 +11,7 @@ index b3dddeeaa2..a77cdad5f4 100644
  namespace Clipper2Lib
  {
  
-@@ -78,18 +80,18 @@ namespace Clipper2Lib
+@@ -79,18 +81,18 @@ namespace Clipper2Lib
      switch (error_code)
      {
      case precision_error_i:

thirdparty/clipper2/patches/gcc14-warning.patch

@@ -1,22 +0,0 @@
-diff --git a/thirdparty/clipper2/include/clipper2/clipper.core.h b/thirdparty/clipper2/include/clipper2/clipper.core.h
-index a77cdad5f4..0de7c3720e 100644
---- a/thirdparty/clipper2/include/clipper2/clipper.core.h
-+++ b/thirdparty/clipper2/include/clipper2/clipper.core.h
-@@ -138,7 +138,7 @@ namespace Clipper2Lib
-     }
- 
-     template <typename T2>
--    explicit Point<T>(const Point<T2>& p)
-+    explicit Point(const Point<T2>& p)
-     {
-       Init(p.x, p.y, p.z);
-     }
-@@ -180,7 +180,7 @@ namespace Clipper2Lib
-     Point(const T2 x_, const T2 y_) { Init(x_, y_); }
- 
-     template <typename T2>
--    explicit Point<T>(const Point<T2>& p) { Init(p.x, p.y); }
-+    explicit Point(const Point<T2>& p) { Init(p.x, p.y); }
- 
-     Point operator * (const double scale) const
-     {

thirdparty/clipper2/patches/llvm-error.patch

@@ -0,0 +1,34 @@
+diff --git a/thirdparty/clipper2/include/clipper2/clipper.core.h b/thirdparty/clipper2/include/clipper2/clipper.core.h
+index 67dd731af6..0f69bf2d9f 100644
+--- a/thirdparty/clipper2/include/clipper2/clipper.core.h
++++ b/thirdparty/clipper2/include/clipper2/clipper.core.h
+@@ -695,11 +695,13 @@ namespace Clipper2Lib
+   // returns true if (and only if) a * b == c * d
+   inline bool ProductsAreEqual(int64_t a, int64_t b, int64_t c, int64_t d)
+   {
+-#if (defined(__clang__) || defined(__GNUC__)) && UINTPTR_MAX >= UINT64_MAX
+-    const auto ab = static_cast<__int128_t>(a) * static_cast<__int128_t>(b);
+-    const auto cd = static_cast<__int128_t>(c) * static_cast<__int128_t>(d);
+-    return ab == cd;
+-#else
++// -- GODOT start --
++// #if (defined(__clang__) || defined(__GNUC__)) && UINTPTR_MAX >= UINT64_MAX
++//     const auto ab = static_cast<__int128_t>(a) * static_cast<__int128_t>(b);
++//     const auto cd = static_cast<__int128_t>(c) * static_cast<__int128_t>(d);
++//     return ab == cd;
++// #else
++// -- GODOT end --
+     // nb: unsigned values needed for calculating overflow carry
+     const auto abs_a = static_cast<uint64_t>(std::abs(a));
+     const auto abs_b = static_cast<uint64_t>(std::abs(b));
+@@ -714,7 +716,9 @@ namespace Clipper2Lib
+     const auto sign_cd = TriSign(c) * TriSign(d);
+ 
+     return abs_ab == abs_cd && sign_ab == sign_cd;
+-#endif
++// -- GODOT start --
++// #endif
++// -- GODOT end --
+   }
+ 
+   template <typename T>

thirdparty/clipper2/src/clipper.engine.cpp

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  22 November 2023                                                *
+* Date      :  27 April 2024                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  This is the main polygon clipping module                        *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -31,11 +31,11 @@ namespace Clipper2Lib {
 
   static const Rect64 invalid_rect = Rect64(false);
 
-  // Every closed path (or polygon) is made up of a series of vertices forming
-  // edges that alternate between going up (relative to the Y-axis) and going
-  // down. Edges consecutively going up or consecutively going down are called
-  // 'bounds' (ie sides if they're simple polygons). 'Local Minima' refer to
-  // vertices where descending bounds become ascending ones.
+  // Every closed path (ie polygon) is made up of a series of vertices forming edge 
+  // 'bounds' that alternate between ascending bounds (containing edges going up 
+  // relative to the Y-axis) and descending bounds. 'Local Minima' refers to
+  // vertices where ascending and descending bounds join at the bottom, and
+  // 'Local Maxima' are where ascending and descending bounds join at the top.
 
   struct Scanline {
     int64_t y = 0;
@@ -63,6 +63,7 @@ namespace Clipper2Lib {
     }
   };
 
+
   inline bool IsOdd(int val)
   {
     return (val & 1) ? true : false;
@@ -188,7 +189,7 @@ namespace Clipper2Lib {
   }
 
   //PrevPrevVertex: useful to get the (inverted Y-axis) top of the
-  //alternate edge (ie left or right bound) during edge insertion.  
+  //alternate edge (ie left or right bound) during edge insertion.
   inline Vertex* PrevPrevVertex(const Active& ae)
   {
     if (ae.wind_dx > 0)
@@ -233,15 +234,15 @@ namespace Clipper2Lib {
     Vertex* result = e.vertex_top;
     if (e.wind_dx > 0)
       while ((result->next->pt.y == result->pt.y) &&
-        ((result->flags & (VertexFlags::OpenEnd | 
+        ((result->flags & (VertexFlags::OpenEnd |
           VertexFlags::LocalMax)) == VertexFlags::None))
             result = result->next;
     else
       while (result->prev->pt.y == result->pt.y &&
-        ((result->flags & (VertexFlags::OpenEnd | 
+        ((result->flags & (VertexFlags::OpenEnd |
           VertexFlags::LocalMax)) == VertexFlags::None))
           result = result->prev;
-    if (!IsMaxima(*result)) result = nullptr; // not a maxima   
+    if (!IsMaxima(*result)) result = nullptr; // not a maxima
     return result;
   }
 
@@ -252,7 +253,7 @@ namespace Clipper2Lib {
       while (result->next->pt.y == result->pt.y) result = result->next;
     else
       while (result->prev->pt.y == result->pt.y) result = result->prev;
-    if (!IsMaxima(*result)) result = nullptr; // not a maxima   
+    if (!IsMaxima(*result)) result = nullptr; // not a maxima
     return result;
   }
 
@@ -613,13 +614,13 @@ namespace Clipper2Lib {
     list.push_back(std::make_unique <LocalMinima>(&vert, polytype, is_open));
   }
 
-  void AddPaths_(const Paths64& paths, PathType polytype, bool is_open, 
+  void AddPaths_(const Paths64& paths, PathType polytype, bool is_open,
     std::vector<Vertex*>& vertexLists, LocalMinimaList& locMinList)
   {
     const auto total_vertex_count =
-      std::accumulate(paths.begin(), paths.end(), 0,
+      std::accumulate(paths.begin(), paths.end(), size_t(0),
         [](const auto& a, const Path64& path)
-        {return a + static_cast<unsigned>(path.size()); });
+        {return a + path.size(); });
     if (total_vertex_count == 0) return;
 
     Vertex* vertices = new Vertex[total_vertex_count], * v = vertices;
@@ -810,7 +811,7 @@ namespace Clipper2Lib {
   void ClipperBase::SetZ(const Active& e1, const Active& e2, Point64& ip)
   {
     if (!zCallback_) return;
-    // prioritize subject over clip vertices by passing 
+    // prioritize subject over clip vertices by passing
     // subject vertices before clip vertices in the callback
     if (GetPolyType(e1) == PathType::Subject)
     {
@@ -845,11 +846,11 @@ namespace Clipper2Lib {
     if (is_open) has_open_paths_ = true;
     minima_list_sorted_ = false;
     AddPaths_(paths, polytype, is_open, vertex_lists_, minima_list_);
-  } 
+  }
 
-  void ClipperBase::AddReuseableData(const ReuseableDataContainer64& reuseable_data) 
+  void ClipperBase::AddReuseableData(const ReuseableDataContainer64& reuseable_data)
   {
-    // nb: reuseable_data will continue to own the vertices 
+    // nb: reuseable_data will continue to own the vertices
     // and remains responsible for their clean up.
     succeeded_ = false;
     minima_list_sorted_ = false;
@@ -1117,7 +1118,6 @@ namespace Clipper2Lib {
     }
   }
 
-
   bool IsValidAelOrder(const Active& resident, const Active& newcomer)
   {
     if (newcomer.curr_x != resident.curr_x)
@@ -1149,8 +1149,8 @@ namespace Clipper2Lib {
     //resident must also have just been inserted
     else if (resident.is_left_bound != newcomerIsLeft)
       return newcomerIsLeft;
-    else if (CrossProduct(PrevPrevVertex(resident)->pt,
-      resident.bot, resident.top) == 0) return true;
+    else if (IsCollinear(PrevPrevVertex(resident)->pt,
+      resident.bot, resident.top)) return true;
     else
       //compare turning direction of the alternate bound
       return (CrossProduct(PrevPrevVertex(resident)->pt,
@@ -1385,7 +1385,7 @@ namespace Clipper2Lib {
   {
     if (IsJoined(e1)) Split(e1, pt);
     if (IsJoined(e2)) Split(e2, pt);
-    
+
     if (IsFront(e1) == IsFront(e2))
     {
       if (IsOpenEnd(e1))
@@ -1409,7 +1409,7 @@ namespace Clipper2Lib {
       {
         Active* e = GetPrevHotEdge(e1);
         if (!e)
-          outrec.owner = nullptr; 
+          outrec.owner = nullptr;
         else
           SetOwner(&outrec, e->outrec);
         // nb: outRec.owner here is likely NOT the real
@@ -1476,7 +1476,7 @@ namespace Clipper2Lib {
       e2.outrec->pts = e1.outrec->pts;
       e1.outrec->pts = nullptr;
     }
-    else 
+    else
       SetOwner(e2.outrec, e1.outrec);
 
     //and e1 and e2 are maxima and are about to be dropped from the Actives list.
@@ -1526,7 +1526,6 @@ namespace Clipper2Lib {
     return new_op;
   }
 
-
   void ClipperBase::CleanCollinear(OutRec* outrec)
   {
     outrec = GetRealOutRec(outrec);
@@ -1541,7 +1540,7 @@ namespace Clipper2Lib {
     for (; ; )
     {
       //NB if preserveCollinear == true, then only remove 180 deg. spikes
-      if ((CrossProduct(op2->prev->pt, op2->pt, op2->next->pt) == 0) &&
+      if (IsCollinear(op2->prev->pt, op2->pt, op2->next->pt) &&
         (op2->pt == op2->prev->pt ||
           op2->pt == op2->next->pt || !preserve_collinear_ ||
           DotProduct(op2->prev->pt, op2->pt, op2->next->pt) < 0))
@@ -1566,14 +1565,14 @@ namespace Clipper2Lib {
 
   void ClipperBase::DoSplitOp(OutRec* outrec, OutPt* splitOp)
   {
-    // splitOp.prev -> splitOp && 
+    // splitOp.prev -> splitOp &&
     // splitOp.next -> splitOp.next.next are intersecting
     OutPt* prevOp = splitOp->prev;
     OutPt* nextNextOp = splitOp->next->next;
     outrec->pts = prevOp;
 
     Point64 ip;
-    GetIntersectPoint(prevOp->pt, splitOp->pt,
+    GetSegmentIntersectPt(prevOp->pt, splitOp->pt,
       splitOp->next->pt, nextNextOp->pt, ip);
 
 #ifdef USINGZ
@@ -1617,7 +1616,7 @@ namespace Clipper2Lib {
     {
       OutRec* newOr = NewOutRec();
       newOr->owner = outrec->owner;
-      
+
       splitOp->outrec = newOr;
       splitOp->next->outrec = newOr;
       OutPt* newOp = new OutPt(ip, newOr);
@@ -1772,12 +1771,12 @@ namespace Clipper2Lib {
   }
 
 
-  OutPt* ClipperBase::IntersectEdges(Active& e1, Active& e2, const Point64& pt)
+  void ClipperBase::IntersectEdges(Active& e1, Active& e2, const Point64& pt)
   {
     //MANAGE OPEN PATH INTERSECTIONS SEPARATELY ...
     if (has_open_paths_ && (IsOpen(e1) || IsOpen(e2)))
     {
-      if (IsOpen(e1) && IsOpen(e2)) return nullptr;
+      if (IsOpen(e1) && IsOpen(e2)) return;
       Active* edge_o, * edge_c;
       if (IsOpen(e1))
       {
@@ -1791,29 +1790,40 @@ namespace Clipper2Lib {
       }
       if (IsJoined(*edge_c)) Split(*edge_c, pt); // needed for safety
 
-      if (abs(edge_c->wind_cnt) != 1) return nullptr;
+      if (abs(edge_c->wind_cnt) != 1) return;
       switch (cliptype_)
       {
       case ClipType::Union:
-        if (!IsHotEdge(*edge_c)) return nullptr;
+        if (!IsHotEdge(*edge_c)) return;
         break;
       default:
         if (edge_c->local_min->polytype == PathType::Subject)
-          return nullptr;
+          return;
       }
 
       switch (fillrule_)
       {
-      case FillRule::Positive: if (edge_c->wind_cnt != 1) return nullptr; break;
-      case FillRule::Negative: if (edge_c->wind_cnt != -1) return nullptr; break;
-      default: if (std::abs(edge_c->wind_cnt) != 1) return nullptr; break;
+      case FillRule::Positive: 
+        if (edge_c->wind_cnt != 1) return; 
+        break;
+      case FillRule::Negative: 
+        if (edge_c->wind_cnt != -1) return; 
+        break;
+      default: 
+        if (std::abs(edge_c->wind_cnt) != 1) return; 
       }
 
+#ifdef USINGZ
       OutPt* resultOp;
+#endif
       //toggle contribution ...
       if (IsHotEdge(*edge_o))
       {
+#ifdef USINGZ
         resultOp = AddOutPt(*edge_o, pt);
+#else
+        AddOutPt(*edge_o, pt);
+#endif
         if (IsFront(*edge_o)) edge_o->outrec->front_edge = nullptr;
         else edge_o->outrec->back_edge = nullptr;
         edge_o->outrec = nullptr;
@@ -1833,18 +1843,26 @@ namespace Clipper2Lib {
             SetSides(*e3->outrec, *edge_o, *e3);
           else
             SetSides(*e3->outrec, *e3, *edge_o);
-          return e3->outrec->pts;
+          return;
         }
         else
+#ifdef USINGZ
           resultOp = StartOpenPath(*edge_o, pt);
+#else
+          StartOpenPath(*edge_o, pt);
+#endif
       }
       else
+#ifdef USINGZ
         resultOp = StartOpenPath(*edge_o, pt);
+#else
+        StartOpenPath(*edge_o, pt);
+#endif
 
 #ifdef USINGZ
       if (zCallback_) SetZ(*edge_o, *edge_c, resultOp->pt);
 #endif
-      return resultOp;
+      return;
     } // end of an open path intersection
 
     //MANAGING CLOSED PATHS FROM HERE ON
@@ -1913,22 +1931,25 @@ namespace Clipper2Lib {
     const bool e1_windcnt_in_01 = old_e1_windcnt == 0 || old_e1_windcnt == 1;
     const bool e2_windcnt_in_01 = old_e2_windcnt == 0 || old_e2_windcnt == 1;
 
-    if ((!IsHotEdge(e1) && !e1_windcnt_in_01) || (!IsHotEdge(e2) && !e2_windcnt_in_01))
-    {
-      return nullptr;
-    }
+    if ((!IsHotEdge(e1) && !e1_windcnt_in_01) || 
+      (!IsHotEdge(e2) && !e2_windcnt_in_01))
+        return;
 
     //NOW PROCESS THE INTERSECTION ...
+#ifdef USINGZ
     OutPt* resultOp = nullptr;
+#endif
     //if both edges are 'hot' ...
     if (IsHotEdge(e1) && IsHotEdge(e2))
     {
       if ((old_e1_windcnt != 0 && old_e1_windcnt != 1) || (old_e2_windcnt != 0 && old_e2_windcnt != 1) ||
         (e1.local_min->polytype != e2.local_min->polytype && cliptype_ != ClipType::Xor))
       {
-        resultOp = AddLocalMaxPoly(e1, e2, pt);
 #ifdef USINGZ
+        resultOp = AddLocalMaxPoly(e1, e2, pt);
         if (zCallback_ && resultOp) SetZ(e1, e2, resultOp->pt);
+#else
+        AddLocalMaxPoly(e1, e2, pt);
 #endif
       }
       else if (IsFront(e1) || (e1.outrec == e2.outrec))
@@ -1937,19 +1958,20 @@ namespace Clipper2Lib {
         //it's sensible to split polygons that ony touch at
         //a common vertex (not at common edges).
 
-        resultOp = AddLocalMaxPoly(e1, e2, pt);
 #ifdef USINGZ
+        resultOp = AddLocalMaxPoly(e1, e2, pt);
         OutPt* op2 = AddLocalMinPoly(e1, e2, pt);
         if (zCallback_ && resultOp) SetZ(e1, e2, resultOp->pt);
         if (zCallback_) SetZ(e1, e2, op2->pt);
 #else
+        AddLocalMaxPoly(e1, e2, pt);
         AddLocalMinPoly(e1, e2, pt);
 #endif
       }
       else
       {
-        resultOp = AddOutPt(e1, pt);
 #ifdef USINGZ
+        resultOp = AddOutPt(e1, pt);
         OutPt* op2 = AddOutPt(e2, pt);
         if (zCallback_)
         {
@@ -1957,6 +1979,7 @@ namespace Clipper2Lib {
           SetZ(e1, e2, op2->pt);
         }
 #else
+        AddOutPt(e1, pt);
         AddOutPt(e2, pt);
 #endif
         SwapOutrecs(e1, e2);
@@ -1964,17 +1987,21 @@ namespace Clipper2Lib {
     }
     else if (IsHotEdge(e1))
     {
-      resultOp = AddOutPt(e1, pt);
 #ifdef USINGZ
+      resultOp = AddOutPt(e1, pt);
       if (zCallback_) SetZ(e1, e2, resultOp->pt);
+#else
+      AddOutPt(e1, pt);
 #endif
       SwapOutrecs(e1, e2);
     }
     else if (IsHotEdge(e2))
     {
-      resultOp = AddOutPt(e2, pt);
 #ifdef USINGZ
+      resultOp = AddOutPt(e2, pt);
       if (zCallback_) SetZ(e1, e2, resultOp->pt);
+#else
+      AddOutPt(e2, pt);
 #endif
       SwapOutrecs(e1, e2);
     }
@@ -2004,33 +2031,53 @@ namespace Clipper2Lib {
 
       if (!IsSamePolyType(e1, e2))
       {
-        resultOp = AddLocalMinPoly(e1, e2, pt, false);
 #ifdef USINGZ
+        resultOp = AddLocalMinPoly(e1, e2, pt, false);
         if (zCallback_) SetZ(e1, e2, resultOp->pt);
+#else
+        AddLocalMinPoly(e1, e2, pt, false);
 #endif
       }
       else if (old_e1_windcnt == 1 && old_e2_windcnt == 1)
       {
+#ifdef USINGZ
         resultOp = nullptr;
+#endif
         switch (cliptype_)
         {
         case ClipType::Union:
           if (e1Wc2 <= 0 && e2Wc2 <= 0)
+#ifdef USINGZ
             resultOp = AddLocalMinPoly(e1, e2, pt, false);
+#else
+            AddLocalMinPoly(e1, e2, pt, false);
+#endif
           break;
         case ClipType::Difference:
           if (((GetPolyType(e1) == PathType::Clip) && (e1Wc2 > 0) && (e2Wc2 > 0)) ||
             ((GetPolyType(e1) == PathType::Subject) && (e1Wc2 <= 0) && (e2Wc2 <= 0)))
           {
+#ifdef USINGZ
             resultOp = AddLocalMinPoly(e1, e2, pt, false);
+#else
+            AddLocalMinPoly(e1, e2, pt, false);
+#endif
           }
           break;
         case ClipType::Xor:
+#ifdef USINGZ
           resultOp = AddLocalMinPoly(e1, e2, pt, false);
+#else
+          AddLocalMinPoly(e1, e2, pt, false);
+#endif
           break;
         default:
           if (e1Wc2 > 0 && e2Wc2 > 0)
+#ifdef USINGZ
             resultOp = AddLocalMinPoly(e1, e2, pt, false);
+#else
+            AddLocalMinPoly(e1, e2, pt, false);
+#endif
           break;
         }
 #ifdef USINGZ
@@ -2038,7 +2085,6 @@ namespace Clipper2Lib {
 #endif
       }
     }
-    return resultOp;
   }
 
   inline void ClipperBase::DeleteFromAEL(Active& e)
@@ -2065,7 +2111,7 @@ namespace Clipper2Lib {
       e->next_in_sel = e->next_in_ael;
       e->jump = e->next_in_sel;
       if (e->join_with == JoinWith::Left)
-        e->curr_x = e->prev_in_ael->curr_x; // also avoids complications      
+        e->curr_x = e->prev_in_ael->curr_x; // also avoids complications
       else
         e->curr_x = TopX(*e, top_y);
       e = e->next_in_ael;
@@ -2138,7 +2184,7 @@ namespace Clipper2Lib {
     if (outrecHasEdges)
     {
       OutPt* opA = outrec->pts, * opZ = opA->next;
-      while (opP != opZ && opP->prev->pt.y == curr_y) 
+      while (opP != opZ && opP->prev->pt.y == curr_y)
         opP = opP->prev;
       while (opN != opA && opN->next->pt.y == curr_y)
         opN = opN->next;
@@ -2150,7 +2196,7 @@ namespace Clipper2Lib {
       while (opN->next != opP && opN->next->pt.y == curr_y)
         opN = opN->next;
     }
-    bool result = 
+    bool result =
       SetHorzSegHeadingForward(hs, opP, opN) &&
       !hs.left_op->horz;
 
@@ -2160,13 +2206,14 @@ namespace Clipper2Lib {
       hs.right_op = nullptr; // (for sorting)
     return result;
   }
-  
+
   void ClipperBase::ConvertHorzSegsToJoins()
   {
-    auto j = std::count_if(horz_seg_list_.begin(), 
+    auto j = std::count_if(horz_seg_list_.begin(),
       horz_seg_list_.end(),
       [](HorzSegment& hs) { return UpdateHorzSegment(hs); });
     if (j < 2) return;
+
     std::stable_sort(horz_seg_list_.begin(), horz_seg_list_.end(), HorzSegSorter());
 
     HorzSegmentList::iterator hs1 = horz_seg_list_.begin(), hs2;
@@ -2207,8 +2254,8 @@ namespace Clipper2Lib {
             DuplicateOp(hs1->left_op, false));
           horz_join_list_.push_back(join);
         }
-      } 
-    } 
+      }
+    }
   }
 
   void MoveSplits(OutRec* fromOr, OutRec* toOr)
@@ -2301,7 +2348,7 @@ namespace Clipper2Lib {
   void ClipperBase::AddNewIntersectNode(Active& e1, Active& e2, int64_t top_y)
   {
     Point64 ip;
-    if (!GetIntersectPoint(e1.bot, e1.top, e2.bot, e2.top, ip))
+    if (!GetSegmentIntersectPt(e1.bot, e1.top, e2.bot, e2.top, ip))
       ip = Point64(e1.curr_x, top_y); //parallel edges
 
     //rounding errors can occasionally place the calculated intersection
@@ -2321,7 +2368,7 @@ namespace Clipper2Lib {
         ip = GetClosestPointOnSegment(ip, e1.bot, e1.top);
       else if (abs_dx2 > 100)
         ip = GetClosestPointOnSegment(ip, e2.bot, e2.top);
-      else 
+      else
       {
         if (ip.y < top_y) ip.y = top_y;
         else ip.y = bot_y_;
@@ -2453,7 +2500,7 @@ namespace Clipper2Lib {
     horz_seg_list_.push_back(HorzSegment(op));
   }
 
-  bool ClipperBase::ResetHorzDirection(const Active& horz, 
+  bool ClipperBase::ResetHorzDirection(const Active& horz,
     const Vertex* max_vertex, int64_t& horz_left, int64_t& horz_right)
   {
     if (horz.bot.x == horz.top.x)
@@ -2536,8 +2583,8 @@ namespace Clipper2Lib {
           if (IsHotEdge(horz) && IsJoined(*e))
             Split(*e, e->top);
 
-          //if (IsHotEdge(horz) != IsHotEdge(*e)) 
-          //  DoError(undefined_error_i);
+          //if (IsHotEdge(horz) != IsHotEdge(*e))
+          //    DoError(undefined_error_i);
 
           if (IsHotEdge(horz))
           {
@@ -2641,7 +2688,7 @@ namespace Clipper2Lib {
         ResetHorzDirection(horz, vertex_max, horz_left, horz_right);
     }
 
-    if (IsHotEdge(horz)) 
+    if (IsHotEdge(horz))
     {
       OutPt* op = AddOutPt(horz, horz.top);
       AddTrialHorzJoin(op);
@@ -2754,21 +2801,23 @@ namespace Clipper2Lib {
     }
   }
 
-  void ClipperBase::CheckJoinLeft(Active& e, 
+  void ClipperBase::CheckJoinLeft(Active& e,
     const Point64& pt, bool check_curr_x)
   {
     Active* prev = e.prev_in_ael;
-    if (IsOpen(e) || !IsHotEdge(e) || !prev ||
-      IsOpen(*prev) || !IsHotEdge(*prev)) return;
+    if (!prev ||
+      !IsHotEdge(e) || !IsHotEdge(*prev) ||
+      IsHorizontal(e) || IsHorizontal(*prev) ||
+      IsOpen(e) || IsOpen(*prev) ) return;
     if ((pt.y < e.top.y + 2 || pt.y < prev->top.y + 2) &&
-      ((e.bot.y > pt.y) || (prev->bot.y > pt.y))) return; // avoid trivial joins              
+      ((e.bot.y > pt.y) || (prev->bot.y > pt.y))) return; // avoid trivial joins
 
     if (check_curr_x)
     {
-      if (DistanceFromLineSqrd(pt, prev->bot, prev->top) > 0.25) return;
+      if (PerpendicDistFromLineSqrd(pt, prev->bot, prev->top) > 0.25) return;
     }
     else if (e.curr_x != prev->curr_x) return;
-    if (CrossProduct(e.top, pt, prev->top)) return;
+    if (!IsCollinear(e.top, pt, prev->top)) return;
 
     if (e.outrec->idx == prev->outrec->idx)
       AddLocalMaxPoly(*prev, e, pt);
@@ -2780,22 +2829,24 @@ namespace Clipper2Lib {
     e.join_with = JoinWith::Left;
   }
 
-  void ClipperBase::CheckJoinRight(Active& e, 
+  void ClipperBase::CheckJoinRight(Active& e,
     const Point64& pt, bool check_curr_x)
   {
     Active* next = e.next_in_ael;
-    if (IsOpen(e) || !IsHotEdge(e) ||
-      !next || IsOpen(*next) || !IsHotEdge(*next)) return;
+    if (!next ||
+      !IsHotEdge(e) || !IsHotEdge(*next) ||
+      IsHorizontal(e) || IsHorizontal(*next) ||
+      IsOpen(e) || IsOpen(*next)) return;
     if ((pt.y < e.top.y +2 || pt.y < next->top.y +2) &&
-      ((e.bot.y > pt.y) || (next->bot.y > pt.y))) return; // avoid trivial joins              
+      ((e.bot.y > pt.y) || (next->bot.y > pt.y))) return; // avoid trivial joins
 
     if (check_curr_x)
     {
-      if (DistanceFromLineSqrd(pt, next->bot, next->top) > 0.35) return;
+      if (PerpendicDistFromLineSqrd(pt, next->bot, next->top) > 0.35) return;
     }
     else if (e.curr_x != next->curr_x) return;
-    if (CrossProduct(e.top, pt, next->top)) return;
-      
+    if (!IsCollinear(e.top, pt, next->top)) return;
+
     if (e.outrec->idx == next->outrec->idx)
       AddLocalMaxPoly(e, *next, pt);
     else if (e.outrec->idx < next->outrec->idx)
@@ -2863,7 +2914,7 @@ namespace Clipper2Lib {
         op2 = op2->next;
     }
 
-    if (path.size() == 3 && IsVerySmallTriangle(*op2)) return false;
+    if (!isOpen && path.size() == 3 && IsVerySmallTriangle(*op2)) return false;
     else return true;
   }
 
@@ -2872,8 +2923,8 @@ namespace Clipper2Lib {
     if (!outrec->pts) return false;
     if (!outrec->bounds.IsEmpty()) return true;
     CleanCollinear(outrec);
-    if (!outrec->pts || 
-      !BuildPath64(outrec->pts, reverse_solution_, false, outrec->path)){ 
+    if (!outrec->pts ||
+      !BuildPath64(outrec->pts, reverse_solution_, false, outrec->path)){
         return false;}
     outrec->bounds = GetBounds(outrec->path);
     return true;
@@ -2887,10 +2938,10 @@ namespace Clipper2Lib {
       if(!split || split == outrec || split->recursive_split == outrec) continue;
       split->recursive_split = outrec; // prevent infinite loops
 
-      if (split->splits && CheckSplitOwner(outrec, split->splits)) 
+      if (split->splits && CheckSplitOwner(outrec, split->splits))
           return true;
-      else if (CheckBounds(split) && 
-        IsValidOwner(outrec, split) && 
+      else if (CheckBounds(split) &&
+        IsValidOwner(outrec, split) &&
         split->bounds.Contains(outrec->bounds) &&
         Path1InsidePath2(outrec->pts, split->pts))
       {
@@ -2919,7 +2970,7 @@ namespace Clipper2Lib {
 
     if (outrec->owner)
     {
-      if (!outrec->owner->polypath) 
+      if (!outrec->owner->polypath)
         RecursiveCheckOwners(outrec->owner, polypath);
       outrec->polypath = outrec->owner->polypath->AddChild(outrec->path);
     }
@@ -2968,7 +3019,7 @@ namespace Clipper2Lib {
     open_paths.resize(0);
     if (has_open_paths_)
       open_paths.reserve(outrec_list_.size());
-    
+
     // outrec_list_.size() is not static here because
     // CheckBounds below can indirectly add additional
     // OutRec (via FixOutRecPts & CleanCollinear)
@@ -2991,7 +3042,7 @@ namespace Clipper2Lib {
 
   bool BuildPathD(OutPt* op, bool reverse, bool isOpen, PathD& path, double inv_scale)
   {
-    if (!op || op->next == op || (!isOpen && op->next == op->prev)) 
+    if (!op || op->next == op || (!isOpen && op->next == op->prev))
       return false;
 
     path.resize(0);
@@ -3024,7 +3075,7 @@ namespace Clipper2Lib {
 #else
         path.push_back(PointD(lastPt.x * inv_scale, lastPt.y * inv_scale));
 #endif
-        
+
       }
       if (reverse)
         op2 = op2->prev;

thirdparty/clipper2/src/clipper.offset.cpp

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  28 November 2023                                                *
+* Date      :  17 April 2024                                                   *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -20,60 +20,19 @@ const double floating_point_tolerance = 1e-12;
 // Miscellaneous methods
 //------------------------------------------------------------------------------
 
-inline bool ToggleBoolIf(bool val, bool condition)
+std::optional<size_t> GetLowestClosedPathIdx(const Paths64& paths)
 {
-	return condition ? !val : val;
-}
-
-void GetMultiBounds(const Paths64& paths, std::vector<Rect64>& recList)
-{
-	recList.reserve(paths.size());
-	for (const Path64& path : paths)
-	{ 
-		if (path.size() < 1)
-		{
-			recList.push_back(InvalidRect64);
-			continue;
-		}
-		int64_t x = path[0].x, y = path[0].y;
-		Rect64 r = Rect64(x, y, x, y);
-		for (const Point64& pt : path)
-		{
-			if (pt.y > r.bottom) r.bottom = pt.y;
-			else if (pt.y < r.top) r.top = pt.y;
-			if (pt.x > r.right) r.right = pt.x;
-			else if (pt.x < r.left) r.left = pt.x;
-		}
-		recList.push_back(r);
-	}
-}
-
-bool ValidateBounds(std::vector<Rect64>& recList, double delta)
-{
-	int64_t int_delta = static_cast<int64_t>(delta);
-	int64_t big = MAX_COORD - int_delta;
-	int64_t small = MIN_COORD + int_delta;
-	for (const Rect64& r : recList)
-	{
-		if (!r.IsValid()) continue; // ignore invalid paths
-		else if (r.left < small || r.right > big ||
-			r.top < small || r.bottom > big) return false;
-	}
-	return true;
-}
-
-int GetLowestClosedPathIdx(std::vector<Rect64>& boundsList)
-{
-	int i = -1, result = -1;
+    std::optional<size_t> result;
 	Point64 botPt = Point64(INT64_MAX, INT64_MIN);
-	for (const Rect64& r : boundsList)
-	{		
-		++i;
-		if (!r.IsValid()) continue; // ignore invalid paths
-		else if (r.bottom > botPt.y || (r.bottom == botPt.y && r.left < botPt.x))
+	for (size_t i = 0; i < paths.size(); ++i)
+	{
+		for (const Point64& pt : paths[i])
 		{
-			botPt = Point64(r.left, r.bottom);
-			result = static_cast<int>(i);
+			if ((pt.y < botPt.y) || 
+				((pt.y == botPt.y) && (pt.x >= botPt.x))) continue;
+            result = i;
+			botPt.x = pt.x;
+			botPt.y = pt.y;
 		}
 	}
 	return result;
@@ -96,14 +55,14 @@ inline bool AlmostZero(double value, double epsilon = 0.001)
 	return std::fabs(value) < epsilon;
 }
 
-inline double Hypot(double x, double y) 
+inline double Hypot(double x, double y)
 {
 	//see https://stackoverflow.com/a/32436148/359538
 	return std::sqrt(x * x + y * y);
 }
 
 inline PointD NormalizeVector(const PointD& vec)
-{	
+{
 	double h = Hypot(vec.x, vec.y);
 	if (AlmostZero(h)) return PointD(0,0);
 	double inverseHypot = 1 / h;
@@ -164,30 +123,21 @@ ClipperOffset::Group::Group(const Paths64& _paths, JoinType _join_type, EndType
 	for (Path64& p: paths_in)
 	  StripDuplicates(p, is_joined);
 
-	// get bounds of each path --> bounds_list
-	GetMultiBounds(paths_in, bounds_list);
-
 	if (end_type == EndType::Polygon)
 	{
-		is_hole_list.reserve(paths_in.size());
-		for (const Path64& path : paths_in)
-			is_hole_list.push_back(Area(path) < 0);
-		lowest_path_idx = GetLowestClosedPathIdx(bounds_list);
+		lowest_path_idx = GetLowestClosedPathIdx(paths_in);
 		// the lowermost path must be an outer path, so if its orientation is negative,
 		// then flag the whole group is 'reversed' (will negate delta etc.)
 		// as this is much more efficient than reversing every path.
-		is_reversed = (lowest_path_idx >= 0) && is_hole_list[lowest_path_idx];
-		if (is_reversed) is_hole_list.flip();
+        is_reversed = (lowest_path_idx.has_value()) && Area(paths_in[lowest_path_idx.value()]) < 0;
 	}
 	else
 	{
-		lowest_path_idx = -1;
+        lowest_path_idx = std::nullopt;
 		is_reversed = false;
-		is_hole_list.resize(paths_in.size());
 	}
 }
 
-
 //------------------------------------------------------------------------------
 // ClipperOffset methods
 //------------------------------------------------------------------------------
@@ -216,66 +166,29 @@ void ClipperOffset::BuildNormals(const Path64& path)
 	norms.push_back(GetUnitNormal(*path_stop_iter, *(path.cbegin())));
 }
 
-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,
-	const PointD& pt2a, const PointD& pt2b)
-{
-	if (pt1a.x == pt1b.x) //vertical
-	{
-		if (pt2a.x == pt2b.x) return PointD(0, 0);
-
-		double m2 = (pt2b.y - pt2a.y) / (pt2b.x - pt2a.x);
-		double b2 = pt2a.y - m2 * pt2a.x;
-		return PointD(pt1a.x, m2 * pt1a.x + b2);
-	}
-	else if (pt2a.x == pt2b.x) //vertical
-	{
-		double m1 = (pt1b.y - pt1a.y) / (pt1b.x - pt1a.x);
-		double b1 = pt1a.y - m1 * pt1a.x;
-		return PointD(pt2a.x, m1 * pt2a.x + b1);
-	}
-	else
-	{
-		double m1 = (pt1b.y - pt1a.y) / (pt1b.x - pt1a.x);
-		double b1 = pt1a.y - m1 * pt1a.x;
-		double m2 = (pt2b.y - pt2a.y) / (pt2b.x - pt2a.x);
-		double b2 = pt2a.y - m2 * pt2a.x;
-		if (m1 == m2) return PointD(0, 0);
-		double x = (b2 - b1) / (m1 - m2);
-		return PointD(x, m1 * x + b1);
-	}
-}
-
 void ClipperOffset::DoBevel(const Path64& path, size_t j, size_t k)
 {
 	PointD pt1, pt2;
 	if (j == k)
 	{
 		double abs_delta = std::abs(group_delta_);
+#ifdef USINGZ
+		pt1 = PointD(path[j].x - abs_delta * norms[j].x, path[j].y - abs_delta * norms[j].y, path[j].z);
+		pt2 = PointD(path[j].x + abs_delta * norms[j].x, path[j].y + abs_delta * norms[j].y, path[j].z);
+#else
 		pt1 = PointD(path[j].x - abs_delta * norms[j].x, path[j].y - abs_delta * norms[j].y);
 		pt2 = PointD(path[j].x + abs_delta * norms[j].x, path[j].y + abs_delta * norms[j].y);
-	} 
+#endif
+	}
 	else
 	{
+#ifdef USINGZ
+		pt1 = PointD(path[j].x + group_delta_ * norms[k].x, path[j].y + group_delta_ * norms[k].y, path[j].z);
+		pt2 = PointD(path[j].x + group_delta_ * norms[j].x, path[j].y + group_delta_ * norms[j].y, path[j].z);
+#else
 		pt1 = PointD(path[j].x + group_delta_ * norms[k].x, path[j].y + group_delta_ * norms[k].y);
 		pt2 = PointD(path[j].x + group_delta_ * norms[j].x, path[j].y + group_delta_ * norms[j].y);
+#endif
 	}
 	path_out.push_back(Point64(pt1));
 	path_out.push_back(Point64(pt2));
@@ -284,7 +197,7 @@ void ClipperOffset::DoBevel(const Path64& path, size_t j, size_t k)
 void ClipperOffset::DoSquare(const Path64& path, size_t j, size_t k)
 {
 	PointD vec;
-	if (j == k) 
+	if (j == k)
 		vec = PointD(norms[j].y, -norms[j].x);
 	else
 		vec = GetAvgUnitVector(
@@ -304,10 +217,8 @@ void ClipperOffset::DoSquare(const Path64& path, size_t j, size_t k)
 	if (j == k)
 	{
 		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
+		PointD pt = ptQ;
+		GetSegmentIntersectPt(pt1, pt2, pt3, pt4, pt);
 		//get the second intersect point through reflecion
 		path_out.push_back(Point64(ReflectPoint(pt, ptQ)));
 		path_out.push_back(Point64(pt));
@@ -315,10 +226,8 @@ void ClipperOffset::DoSquare(const Path64& path, size_t j, size_t k)
 	else
 	{
 		PointD pt4 = GetPerpendicD(path[j], norms[k], group_delta_);
-		PointD pt = IntersectPoint(pt1, pt2, pt3, pt4);
-#ifdef USINGZ
-		pt.z = ptQ.z;
-#endif
+		PointD pt = ptQ;
+		GetSegmentIntersectPt(pt1, pt2, pt3, pt4, pt);
 		path_out.push_back(Point64(pt));
 		//get the second intersect point through reflecion
 		path_out.push_back(Point64(ReflectPoint(pt, ptQ)));
@@ -343,7 +252,7 @@ void ClipperOffset::DoMiter(const Path64& path, size_t j, size_t k, double cos_a
 void ClipperOffset::DoRound(const Path64& path, size_t j, size_t k, double angle)
 {
 	if (deltaCallback64_) {
-		// when deltaCallback64_ is assigned, group_delta_ won't be constant, 
+		// when deltaCallback64_ is assigned, group_delta_ won't be constant,
 		// so we'll need to do the following calculations for *every* vertex.
 		double abs_delta = std::fabs(group_delta_);
 		double arcTol = (arc_tolerance_ > floating_point_tolerance ?
@@ -387,7 +296,7 @@ void ClipperOffset::OffsetPoint(Group& group, const Path64& path, size_t j, size
 	// sin(A) < 0: right turning
 	// cos(A) < 0: change in angle is more than 90 degree
 
-	if (path[j] == path[k]) { k = j; return; }
+	if (path[j] == path[k]) return;
 
 	double sin_a = CrossProduct(norms[j], norms[k]);
 	double cos_a = DotProduct(norms[j], norms[k]);
@@ -404,18 +313,29 @@ void ClipperOffset::OffsetPoint(Group& group, const Path64& path, size_t j, size
 		return;
 	}
 
-	if (cos_a > -0.99 && (sin_a * group_delta_ < 0)) // test for concavity first (#593)
+	if (cos_a > -0.999 && (sin_a * group_delta_ < 0)) // test for concavity first (#593)
 	{
-		// is concave
+		// is concave (so insert 3 points that will create a negative region)
+#ifdef USINGZ
+		path_out.push_back(Point64(GetPerpendic(path[j], norms[k], group_delta_), path[j].z));
+#else
 		path_out.push_back(GetPerpendic(path[j], norms[k], group_delta_));
-		// this extra point is the only (simple) way to ensure that
-	  // path reversals are fully cleaned with the trailing clipper		
-		path_out.push_back(path[j]); // (#405)
+#endif
+		
+		// this extra point is the only simple way to ensure that path reversals
+		// (ie over-shrunk paths) are fully cleaned out with the trailing union op.
+		// However it's probably safe to skip this whenever an angle is almost flat.
+		if (cos_a < 0.99) path_out.push_back(path[j]); // (#405)
+
+#ifdef USINGZ
+		path_out.push_back(Point64(GetPerpendic(path[j], norms[j], group_delta_), path[j].z));
+#else
 		path_out.push_back(GetPerpendic(path[j], norms[j], group_delta_));
+#endif
 	}
-	else if (cos_a > 0.999 && join_type_ != JoinType::Round) 
+	else if (cos_a > 0.999 && join_type_ != JoinType::Round)
 	{
-		// almost straight - less than 2.5 degree (#424, #482, #526 & #724) 
+		// almost straight - less than 2.5 degree (#424, #482, #526 & #724)
 		DoMiter(path, j, k, cos_a);
 	}
 	else if (join_type_ == JoinType::Miter)
@@ -435,9 +355,9 @@ void ClipperOffset::OffsetPoint(Group& group, const Path64& path, size_t j, size
 void ClipperOffset::OffsetPolygon(Group& group, const Path64& path)
 {
 	path_out.clear();
-	for (Path64::size_type j = 0, k = path.size() -1; j < path.size(); k = j, ++j)
-		OffsetPoint(group, path, j, k);
-	solution.push_back(path_out);
+	for (Path64::size_type j = 0, k = path.size() - 1; j < path.size(); k = j, ++j)
+		OffsetPoint(group, path, j, k);	
+	solution->push_back(path_out);
 }
 
 void ClipperOffset::OffsetOpenJoined(Group& group, const Path64& path)
@@ -445,8 +365,8 @@ void ClipperOffset::OffsetOpenJoined(Group& group, const Path64& path)
 	OffsetPolygon(group, path);
 	Path64 reverse_path(path);
 	std::reverse(reverse_path.begin(), reverse_path.end());
-	
-	//rebuild normals // BuildNormals(path);
+
+	//rebuild normals 
 	std::reverse(norms.begin(), norms.end());
 	norms.push_back(norms[0]);
 	norms.erase(norms.begin());
@@ -459,7 +379,7 @@ void ClipperOffset::OffsetOpenPath(Group& group, const Path64& path)
 {
 	// do the line start cap
 	if (deltaCallback64_) group_delta_ = deltaCallback64_(path, norms, 0, 0);
-	
+
 	if (std::fabs(group_delta_) <= floating_point_tolerance)
 		path_out.push_back(path[0]);
 	else
@@ -477,13 +397,13 @@ void ClipperOffset::OffsetOpenPath(Group& group, const Path64& path)
 			break;
 		}
 	}
-	
+
 	size_t highI = path.size() - 1;
 	// offset the left side going forward
 	for (Path64::size_type j = 1, k = 0; j < highI; k = j, ++j)
 		OffsetPoint(group, path, j, k);
 
-	// reverse normals 
+	// reverse normals
 	for (size_t i = highI; i > 0; --i)
 		norms[i] = PointD(-norms[i - 1].x, -norms[i - 1].y);
 	norms[0] = norms[highI];
@@ -510,41 +430,34 @@ void ClipperOffset::OffsetOpenPath(Group& group, const Path64& path)
 		}
 	}
 
-	for (size_t j = highI, k = 0; j > 0; k = j, --j)
+	for (size_t j = highI -1, k = highI; j > 0; k = j, --j)
 		OffsetPoint(group, path, j, k);
-	solution.push_back(path_out);
+	solution->push_back(path_out);
 }
 
 void ClipperOffset::DoGroupOffset(Group& group)
 {
 	if (group.end_type == EndType::Polygon)
 	{
-		// a straight path (2 points) can now also be 'polygon' offset 
+		// a straight path (2 points) can now also be 'polygon' offset
 		// where the ends will be treated as (180 deg.) joins
-		if (group.lowest_path_idx < 0) delta_ = std::abs(delta_);
+        if (!group.lowest_path_idx.has_value()) delta_ = std::abs(delta_);
 		group_delta_ = (group.is_reversed) ? -delta_ : delta_;
 	}
 	else
 		group_delta_ = std::abs(delta_);// *0.5;
 
 	double abs_delta = std::fabs(group_delta_);
-	if (!ValidateBounds(group.bounds_list, abs_delta))
-	{
-		DoError(range_error_i);
-		error_code_ |= range_error_i;
-		return;
-	}
-
 	join_type_	= group.join_type;
 	end_type_ = group.end_type;
 
 	if (group.join_type == JoinType::Round || group.end_type == EndType::Round)
 	{
-		// calculate a sensible number of steps (for 360 deg for the given offset)
-		// 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
+		// calculate the number of steps required to approximate a circle
+		// (see http://www.angusj.com/clipper2/Docs/Trigonometry.htm)
+		// arcTol - when arc_tolerance_ is undefined (0) then curve imprecision
+		// will be relative to the size of the offset (delta). Obviously very
+		//large offsets will almost always require much less precision.
 		double arcTol = (arc_tolerance_ > floating_point_tolerance ?
 			std::min(abs_delta, arc_tolerance_) :
 			std::log10(2 + abs_delta) * default_arc_tolerance);
@@ -556,24 +469,29 @@ void ClipperOffset::DoGroupOffset(Group& group)
 		steps_per_rad_ = steps_per_360 / (2 * PI);
 	}
 
-	std::vector<Rect64>::const_iterator path_rect_it = group.bounds_list.cbegin();
-	std::vector<bool>::const_iterator is_hole_it = group.is_hole_list.cbegin();
+	//double min_area = PI * Sqr(group_delta_);
 	Paths64::const_iterator path_in_it = group.paths_in.cbegin();
-	for ( ; path_in_it != group.paths_in.cend(); ++path_in_it, ++path_rect_it, ++is_hole_it)
+	for ( ; path_in_it != group.paths_in.cend(); ++path_in_it)
 	{
-		if (!path_rect_it->IsValid()) continue;
 		Path64::size_type pathLen = path_in_it->size();
 		path_out.clear();
 
 		if (pathLen == 1) // single point
 		{
+			if (deltaCallback64_)
+			{
+				group_delta_ = deltaCallback64_(*path_in_it, norms, 0, 0);
+				if (group.is_reversed) group_delta_ = -group_delta_;
+				abs_delta = std::fabs(group_delta_);
+			}
+
 			if (group_delta_ < 1) continue;
 			const Point64& pt = (*path_in_it)[0];
 			//single vertex so build a circle or square ...
 			if (group.join_type == JoinType::Round)
 			{
 				double radius = abs_delta;
-				int steps = static_cast<int>(std::ceil(steps_per_rad_ * 2 * PI)); //#617
+                size_t steps = steps_per_rad_ > 0 ? static_cast<size_t>(std::ceil(steps_per_rad_ * 2 * PI)) : 0; //#617
 				path_out = Ellipse(pt, radius, radius, steps);
 #ifdef USINGZ
 				for (auto& p : path_out) p.z = pt.z;
@@ -588,19 +506,14 @@ void ClipperOffset::DoGroupOffset(Group& group)
 				for (auto& p : path_out) p.z = pt.z;
 #endif
 			}
-			solution.push_back(path_out);
-			continue;
-		} // end of offsetting a single point 
 
-		// when shrinking outer paths, make sure they can shrink this far (#593)
-		// also when shrinking holes, make sure they too can shrink this far (#715)
-		if ((group_delta_ > 0) == ToggleBoolIf(*is_hole_it, group.is_reversed) &&
-			(std::min(path_rect_it->Width(), path_rect_it->Height()) <= -group_delta_ * 2) )
-				  continue;
+			solution->push_back(path_out);
+			continue;
+		} // end of offsetting a single point
 
 		if ((pathLen == 2) && (group.end_type == EndType::Joined))
-			end_type_ = (group.join_type == JoinType::Round) ? 
-			  EndType::Round : 
+			end_type_ = (group.join_type == JoinType::Round) ?
+			  EndType::Round :
 			  EndType::Square;
 
 		BuildNormals(*path_in_it);
@@ -610,6 +523,16 @@ void ClipperOffset::DoGroupOffset(Group& group)
 	}
 }
 
+#ifdef USINGZ
+void ClipperOffset::ZCB(const Point64& bot1, const Point64& top1,
+	const Point64& bot2, const Point64& top2, Point64& ip)
+{
+	if (bot1.z && ((bot1.z == bot2.z) || (bot1.z == top2.z))) ip.z = bot1.z;
+	else if (bot2.z && (bot2.z == top1.z)) ip.z = bot2.z;
+	else if (top1.z && (top1.z == top2.z)) ip.z = top1.z;
+	else if (zCallback64_) zCallback64_(bot1, top1, bot2, top2, ip);
+}
+#endif
 
 size_t ClipperOffset::CalcSolutionCapacity()
 {
@@ -635,40 +558,35 @@ bool ClipperOffset::CheckReverseOrientation()
 void ClipperOffset::ExecuteInternal(double delta)
 {
 	error_code_ = 0;
-	solution.clear();
 	if (groups_.size() == 0) return;
-	solution.reserve(CalcSolutionCapacity());
+	solution->reserve(CalcSolutionCapacity());
 
-	if (std::abs(delta) < 0.5) // ie: offset is insignificant 
+	if (std::abs(delta) < 0.5) // ie: offset is insignificant
 	{
 		Paths64::size_type sol_size = 0;
 		for (const Group& group : groups_) sol_size += group.paths_in.size();
-		solution.reserve(sol_size);
+		solution->reserve(sol_size);
 		for (const Group& group : groups_)
-			copy(group.paths_in.begin(), group.paths_in.end(), back_inserter(solution));
-		return;
+			copy(group.paths_in.begin(), group.paths_in.end(), back_inserter(*solution));
 	}
+	else
+	{
 
-	temp_lim_ = (miter_limit_ <= 1) ?
-		2.0 :
-		2.0 / (miter_limit_ * miter_limit_);
+		temp_lim_ = (miter_limit_ <= 1) ?
+			2.0 :
+			2.0 / (miter_limit_ * miter_limit_);
 
-	delta_ = delta;
-	std::vector<Group>::iterator git;
-	for (git = groups_.begin(); git != groups_.end(); ++git)
-	{
-		DoGroupOffset(*git);
-		if (!error_code_) continue; // all OK
-		solution.clear();
+		delta_ = delta;
+		std::vector<Group>::iterator git;
+		for (git = groups_.begin(); git != groups_.end(); ++git)
+		{
+			DoGroupOffset(*git);
+			if (!error_code_) continue; // all OK
+			solution->clear();
+		}
 	}
-}
 
-void ClipperOffset::Execute(double delta, Paths64& paths)
-{
-	paths.clear();
-
-	ExecuteInternal(delta);
-	if (!solution.size()) return;
+	if (!solution->size()) return;
 
 	bool paths_reversed = CheckReverseOrientation();
 	//clean up self-intersections ...
@@ -677,41 +595,45 @@ void ClipperOffset::Execute(double delta, Paths64& paths)
 	//the solution should retain the orientation of the input
 	c.ReverseSolution(reverse_solution_ != paths_reversed);
 #ifdef USINGZ
-	if (zCallback64_) { c.SetZCallback(zCallback64_); }
+	auto fp = std::bind(&ClipperOffset::ZCB, this, std::placeholders::_1,
+		std::placeholders::_2, std::placeholders::_3,
+		std::placeholders::_4, std::placeholders::_5);
+	c.SetZCallback(fp);
 #endif
-	c.AddSubject(solution);
-	if (paths_reversed)
-		c.Execute(ClipType::Union, FillRule::Negative, paths);
+	c.AddSubject(*solution);
+	if (solution_tree)
+	{
+		if (paths_reversed)
+			c.Execute(ClipType::Union, FillRule::Negative, *solution_tree);
+		else
+			c.Execute(ClipType::Union, FillRule::Positive, *solution_tree);
+	}
 	else
-		c.Execute(ClipType::Union, FillRule::Positive, paths);
+	{
+		if (paths_reversed)
+			c.Execute(ClipType::Union, FillRule::Negative, *solution);
+		else
+			c.Execute(ClipType::Union, FillRule::Positive, *solution);
+	}
+}
+
+void ClipperOffset::Execute(double delta, Paths64& paths)
+{
+	paths.clear();
+	solution = &paths;
+	solution_tree = nullptr;
+	ExecuteInternal(delta);
 }
 
 
 void ClipperOffset::Execute(double delta, PolyTree64& polytree)
 {
 	polytree.Clear();
-
+	solution_tree = &polytree;
+	solution = new Paths64();
 	ExecuteInternal(delta);
-	if (!solution.size()) return;
-
-	bool paths_reversed = CheckReverseOrientation();
-	//clean up self-intersections ...
-	Clipper64 c;
-	c.PreserveCollinear(false);
-	//the solution should retain the orientation of the input
-	c.ReverseSolution (reverse_solution_ != paths_reversed);
-#ifdef USINGZ
-	if (zCallback64_) {
-		c.SetZCallback(zCallback64_);
-	}
-#endif
-	c.AddSubject(solution);
-
-
-	if (paths_reversed)
-		c.Execute(ClipType::Union, FillRule::Negative, polytree);
-	else
-		c.Execute(ClipType::Union, FillRule::Positive, polytree);
+	delete solution;
+	solution = nullptr;
 }
 
 void ClipperOffset::Execute(DeltaCallback64 delta_cb, Paths64& paths)

thirdparty/clipper2/src/clipper.rectclip.cpp

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  8 September 2023                                                *
+* Date      :  5 July 2024                                                     *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2023                                         *
+* Copyright :  Angus Johnson 2010-2024                                         *
 * Purpose   :  FAST rectangular clipping                                       *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
@@ -71,7 +71,7 @@ namespace Clipper2Lib {
     return pt1.y == pt2.y;
   }
 
-  inline bool GetSegmentIntersection(const Point64& p1,
+  bool GetSegmentIntersection(const Point64& p1,
     const Point64& p2, const Point64& p3, const Point64& p4, Point64& ip)
   {
     double res1 = CrossProduct(p1, p3, p4);
@@ -113,7 +113,7 @@ namespace Clipper2Lib {
     if ((res3 > 0) == (res4 > 0)) return false;
 
     // segments must intersect to get here
-    return GetIntersectPoint(p1, p2, p3, p4, ip);
+    return GetSegmentIntersectPt(p1, p2, p3, p4, ip);
   }
 
   inline bool GetIntersection(const Path64& rectPath,
@@ -125,7 +125,7 @@ namespace Clipper2Lib {
     {
     case Location::Left:
       if (GetSegmentIntersection(p, p2, rectPath[0], rectPath[3], ip)) return true;
-      else if ((p.y < rectPath[0].y) && GetSegmentIntersection(p, p2, rectPath[0], rectPath[1], ip))        
+      else if ((p.y < rectPath[0].y) && GetSegmentIntersection(p, p2, rectPath[0], rectPath[1], ip))
       {
         loc = Location::Top;
         return true;
@@ -180,7 +180,7 @@ namespace Clipper2Lib {
       else return false;
 
     default: // loc == rInside
-      if (GetSegmentIntersection(p, p2, rectPath[0], rectPath[3], ip)) 
+      if (GetSegmentIntersection(p, p2, rectPath[0], rectPath[3], ip))
       {
         loc = Location::Left;
         return true;
@@ -320,9 +320,9 @@ namespace Clipper2Lib {
     // 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;
+    size_t curr_idx = results_.size();
     OutPt2* result;
-    if (curr_idx < 0 || start_new)
+    if (curr_idx == 0 || start_new)
     {
       result = &op_container_.emplace_back(OutPt2());
       result->pt = pt;
@@ -332,6 +332,7 @@ namespace Clipper2Lib {
     }
     else
     {
+      --curr_idx;
       OutPt2* prevOp = results_[curr_idx];
       if (prevOp->pt == pt)  return prevOp;
       result = &op_container_.emplace_back(OutPt2());
@@ -349,27 +350,27 @@ namespace Clipper2Lib {
   void RectClip64::AddCorner(Location prev, Location curr)
   {
     if (HeadingClockwise(prev, curr))
-      Add(rect_as_path_[static_cast<int>(prev)]);
+      Add(rect_as_path_[static_cast<size_t>(prev)]);
     else
-      Add(rect_as_path_[static_cast<int>(curr)]);
+      Add(rect_as_path_[static_cast<size_t>(curr)]);
   }
 
   void RectClip64::AddCorner(Location& loc, bool isClockwise)
   {
     if (isClockwise)
     {
-      Add(rect_as_path_[static_cast<int>(loc)]);
+      Add(rect_as_path_[static_cast<size_t>(loc)]);
       loc = GetAdjacentLocation(loc, true);
     }
     else
     {
       loc = GetAdjacentLocation(loc, false);
-      Add(rect_as_path_[static_cast<int>(loc)]);
+      Add(rect_as_path_[static_cast<size_t>(loc)]);
     }
   }
 
   void RectClip64::GetNextLocation(const Path64& path,
-    Location& loc, int& i, int highI)
+    Location& loc, size_t& i, size_t highI)
   {
     switch (loc)
     {
@@ -420,31 +421,52 @@ namespace Clipper2Lib {
         break; //inner loop
       }
       break;
-    } //switch          
+    } //switch
+  }
+
+  bool StartLocsAreClockwise(const std::vector<Location>& startlocs)
+  {
+    int result = 0;
+    for (size_t i = 1; i < startlocs.size(); ++i)
+    {
+      int d = static_cast<int>(startlocs[i]) - static_cast<int>(startlocs[i - 1]);
+      switch (d)
+      {
+        case -1: result -= 1; break;
+        case 1: result += 1; break;
+        case -3: result += 1; break;
+        case 3: result -= 1; break;
+      }
+    }
+    return result > 0;
   }
 
   void RectClip64::ExecuteInternal(const Path64& path)
   {
-    int i = 0, highI = static_cast<int>(path.size()) - 1;
+    if (path.size() < 1)
+      return;
+
+    size_t highI = path.size() - 1;
     Location prev = Location::Inside, loc;
     Location crossing_loc = Location::Inside;
     Location first_cross_ = Location::Inside;
     if (!GetLocation(rect_, path[highI], loc))
     {
-      i = highI - 1;
-      while (i >= 0 && !GetLocation(rect_, path[i], prev)) --i;
-      if (i < 0) 
+      size_t i = highI;
+      while (i > 0 && !GetLocation(rect_, path[i - 1], prev))
+        --i;
+      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 startingLoc = loc;
+    Location starting_loc = loc;
 
     ///////////////////////////////////////////////////
+    size_t i = 0;
     while (i <= highI)
     {
       prev = loc;
@@ -454,12 +476,12 @@ namespace Clipper2Lib {
 
       if (i > highI) break;
       Point64 ip, ip2;
-      Point64 prev_pt = (i) ? 
-        path[static_cast<size_t>(i - 1)] : 
+      Point64 prev_pt = (i) ?
+        path[static_cast<size_t>(i - 1)] :
         path[highI];
 
       crossing_loc = loc;
-      if (!GetIntersection(rect_as_path_, 
+      if (!GetIntersection(rect_as_path_,
         path[i], prev_pt, crossing_loc, ip))
       {
         // ie remaining outside
@@ -470,7 +492,7 @@ namespace Clipper2Lib {
             start_locs_.push_back(prev);
             prev = GetAdjacentLocation(prev, isClockw);
           } while (prev != loc);
-          crossing_loc = crossing_prev; // still not crossed 
+          crossing_loc = crossing_prev; // still not crossed
         }
         else if (prev != Location::Inside && prev != loc)
         {
@@ -504,7 +526,7 @@ namespace Clipper2Lib {
       }
       else if (prev != Location::Inside)
       {
-        // passing right through rect. 'ip' here will be the second 
+        // 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(rect_as_path_, prev_pt, path[i], loc, ip2);
@@ -543,7 +565,7 @@ namespace Clipper2Lib {
     if (first_cross_ == Location::Inside)
     {
       // path never intersects
-      if (startingLoc != Location::Inside)
+      if (starting_loc != Location::Inside)
       {
         // path is outside rect
         // but being outside, it still may not contain rect
@@ -552,11 +574,13 @@ namespace Clipper2Lib {
         {
           // yep, the path does fully contain rect
           // so add rect to the solution
+          bool is_clockwise_path = StartLocsAreClockwise(start_locs_);
           for (size_t j = 0; j < 4; ++j)
           {
-            Add(rect_as_path_[j]);
+            size_t k = is_clockwise_path ? j : 3 - j; // reverses result path
+            Add(rect_as_path_[k]);
             // we may well need to do some splitting later, so
-            AddToEdge(edges_[j * 2], results_[0]);
+            AddToEdge(edges_[k * 2], results_[0]);
           }
         }
       }
@@ -589,8 +613,7 @@ namespace Clipper2Lib {
       OutPt2* op2 = op;
       do
       {
-        if (!CrossProduct(op2->prev->pt,
-          op2->pt, op2->next->pt))
+        if (IsCollinear(op2->prev->pt, op2->pt, op2->next->pt))
         {
           if (op2 == op)
           {
@@ -640,7 +663,7 @@ namespace Clipper2Lib {
     }
   }
 
-  void RectClip64::TidyEdges(int idx, OutPt2List& cw, OutPt2List& ccw)
+  void RectClip64::TidyEdges(size_t idx, OutPt2List& cw, OutPt2List& ccw)
   {
     if (ccw.empty()) return;
     bool isHorz = ((idx == 1) || (idx == 3));
@@ -648,7 +671,7 @@ namespace Clipper2Lib {
     size_t i = 0, j = 0;
     OutPt2* p1, * p2, * p1a, * p2a, * op, * op2;
 
-    while (i < cw.size()) 
+    while (i < cw.size())
     {
       p1 = cw[i];
       if (!p1 || p1->next == p1->prev)
@@ -825,8 +848,8 @@ namespace Clipper2Lib {
     OutPt2* op2 = op->next;
     while (op2 && op2 != op)
     {
-      if (CrossProduct(op2->prev->pt, 
-        op2->pt, op2->next->pt) == 0)
+      if (IsCollinear(op2->prev->pt,
+        op2->pt, op2->next->pt))
       {
         op = op2->prev;
         op2 = UnlinkOp(op2);
@@ -854,7 +877,7 @@ namespace Clipper2Lib {
     if (rect_.IsEmpty()) return result;
 
     for (const Path64& path : paths)
-    {      
+    {
       if (path.size() < 3) continue;
       path_bounds_ = GetBounds(path);
       if (!rect_.Intersects(path_bounds_))
@@ -868,9 +891,9 @@ namespace Clipper2Lib {
 
       ExecuteInternal(path);
       CheckEdges();
-      for (int i = 0; i < 4; ++i)
+      for (size_t i = 0; i < 4; ++i)
         TidyEdges(i, edges_[i * 2], edges_[i * 2 + 1]);
-  
+
       for (OutPt2*& op :  results_)
       {
         Path64 tmp = GetPath(op);
@@ -925,14 +948,14 @@ namespace Clipper2Lib {
     op_container_ = std::deque<OutPt2>();
     start_locs_.clear();
 
-    int i = 1, highI = static_cast<int>(path.size()) - 1;
+    size_t i = 1, highI = path.size() - 1;
 
     Location prev = Location::Inside, loc;
     Location crossing_loc;
     if (!GetLocation(rect_, path[0], loc))
     {
       while (i <= highI && !GetLocation(rect_, path[i], prev)) ++i;
-      if (i > highI) 
+      if (i > highI)
       {
         // all of path must be inside fRect
         for (const auto& pt : path) Add(pt);
@@ -953,7 +976,7 @@ namespace Clipper2Lib {
       Point64 prev_pt = path[static_cast<size_t>(i - 1)];
 
       crossing_loc = loc;
-      if (!GetIntersection(rect_as_path_, 
+      if (!GetIntersection(rect_as_path_,
         path[i], prev_pt, crossing_loc, ip))
       {
         // ie remaining outside
@@ -971,10 +994,10 @@ namespace Clipper2Lib {
       }
       else if (prev != Location::Inside)
       {
-        // passing right through rect. 'ip' here will be the second 
+        // 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(rect_as_path_, 
+        GetIntersection(rect_as_path_,
           prev_pt, path[i], crossing_loc, ip2);
         Add(ip2, true);
         Add(ip);
@@ -991,14 +1014,14 @@ namespace Clipper2Lib {
   {
     Path64 result;
     if (!op || op == op->next) return result;
-    op = op->next; // starting at path beginning 
+    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;
   }