new stuff

vendor/assimp/contrib/poly2tri/AUTHORS

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+Primary Contributors:
+
+  Mason Green <mason.green@gmail.com> (C++, Python)
+  Thomas Åhlén <thahlen@gmail.com>    (Java)
+
+Other Contributors:
+
+  

vendor/assimp/contrib/poly2tri/LICENSE

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+Copyright (c) 2009-2018, Poly2Tri Contributors
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice,
+  this list of conditions and the following disclaimer.
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+* Neither the name of Poly2Tri nor the names of its contributors may be
+  used to endorse or promote products derived from this software without specific
+  prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/assimp/contrib/poly2tri/README.md

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+Since there are no Input validation of the data given for triangulation you need
+to think about this. Poly2Tri does not support repeat points within epsilon.
+
+* If you have a cyclic function that generates random points make sure you don't
+  add the same coordinate twice.
+* If you are given input and aren't sure same point exist twice you need to
+  check for this yourself.
+* Only simple polygons are supported. You may add holes or interior Steiner points
+* Interior holes must not touch other holes, nor touch the polyline boundary
+* Use the library in this order:
+  1. Initialize CDT with a simple polyline (this defines the constrained edges)
+  2. Add holes if necessary (also simple polylines)
+  3. Add Steiner points
+  4. Triangulate
+
+Make sure you understand the preceding notice before posting an issue. If you have
+an issue not covered by the above, include your data-set with the problem.
+The only easy day was yesterday; have a nice day. <Mason Green>
+
+TESTBED INSTALLATION GUIDE
+==========================
+
+Dependencies
+------------
+
+Core poly2tri lib:
+
+* Standard Template Library (STL)
+
+Unit tests:
+* Boost (filesystem, test framework)
+
+Testbed:
+
+* OpenGL
+* [GLFW](http://glfw.sf.net)
+
+Build the library
+-----------------
+
+With the ninja build system installed:
+
+```
+mkdir build && cd build
+cmake -GNinja ..
+cmake --build .
+```
+
+Build and run with unit tests
+----------------------------
+
+With the ninja build system:
+
+```
+mkdir build && cd build
+cmake -GNinja -DP2T_BUILD_TESTS=ON ..
+cmake --build .
+ctest --output-on-failure
+```
+
+Build with the testbed
+-----------------
+
+```
+mkdir build && cd build
+cmake -GNinja -DP2T_BUILD_TESTBED=ON ..
+cmake --build .
+```
+
+Running the Examples
+--------------------
+
+Load data points from a file:
+```
+build/testbed/p2t <filename> <center_x> <center_y> <zoom>
+```
+Load data points from a file and automatically fit the geometry to the window:
+```
+build/testbed/p2t <filename>
+```
+Random distribution of points inside a constrained box:
+```
+build/testbed/p2t random <num_points> <box_radius> <zoom>
+```
+Examples:
+```
+build/testbed/p2t testbed/data/dude.dat 350 500 3
+
+build/testbed/p2t testbed/data/nazca_monkey.dat
+
+build/testbed/p2t random 10 100 5.0
+build/testbed/p2t random 1000 20000 0.025
+```
+
+References
+==========
+
+- Domiter V. and Zalik B. (2008) Sweep‐line algorithm for constrained Delaunay triangulation
+- FlipScan by library author Thomas Åhlén
+
+![FlipScan](doc/FlipScan.png)

vendor/assimp/contrib/poly2tri/poly2tri/common/dll_symbol.h

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+/*
+ * Poly2Tri Copyright (c) 2009-2022, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#if defined(_MSC_VER)
+#  pragma warning( disable: 4273)
+#  define P2T_COMPILER_DLLEXPORT __declspec(dllexport)
+#  define P2T_COMPILER_DLLIMPORT __declspec(dllimport)
+#elif defined(__GNUC__)
+#  define P2T_COMPILER_DLLEXPORT __attribute__ ((visibility ("default")))
+#  define P2T_COMPILER_DLLIMPORT __attribute__ ((visibility ("default")))
+#else
+#  define P2T_COMPILER_DLLEXPORT
+#  define P2T_COMPILER_DLLIMPORT
+#endif
+
+// We need to enable shard linkage explicitely
+#ifdef ASSIMP_BUILD_DLL_EXPORT
+#  define P2T_SHARED_EXPORTS 1
+#endif
+
+#ifndef P2T_DLL_SYMBOL
+#  if defined(P2T_STATIC_EXPORTS)
+#    define P2T_DLL_SYMBOL
+#  elif defined(P2T_SHARED_EXPORTS)
+#    define P2T_DLL_SYMBOL P2T_COMPILER_DLLEXPORT
+#  elif defined(BUILD_SHARED_LIBS)
+#    define P2T_DLL_SYMBOL P2T_COMPILER_DLLIMPORT
+#  else
+#    define P2T_DLL_SYMBOL
+#  endif
+#endif

vendor/assimp/contrib/poly2tri/poly2tri/common/shapes.cc

@@ -0,0 +1,411 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "shapes.h"
+
+#include <cassert>
+#include <iostream>
+
+namespace p2t {
+
+Point::Point(double x, double y) : x(x), y(y)
+{
+}
+
+std::ostream& operator<<(std::ostream& out, const Point& point) {
+  return out << point.x << "," << point.y;
+}
+
+Triangle::Triangle(Point& a, Point& b, Point& c)
+{
+  points_[0] = &a; points_[1] = &b; points_[2] = &c;
+  neighbors_[0] = nullptr; neighbors_[1] = nullptr; neighbors_[2] = nullptr;
+  constrained_edge[0] = constrained_edge[1] = constrained_edge[2] = false;
+  delaunay_edge[0] = delaunay_edge[1] = delaunay_edge[2] = false;
+  interior_ = false;
+}
+
+// Update neighbor pointers
+void Triangle::MarkNeighbor(Point* p1, Point* p2, Triangle* t)
+{
+  if ((p1 == points_[2] && p2 == points_[1]) || (p1 == points_[1] && p2 == points_[2]))
+    neighbors_[0] = t;
+  else if ((p1 == points_[0] && p2 == points_[2]) || (p1 == points_[2] && p2 == points_[0]))
+    neighbors_[1] = t;
+  else if ((p1 == points_[0] && p2 == points_[1]) || (p1 == points_[1] && p2 == points_[0]))
+    neighbors_[2] = t;
+  else
+    assert(0);
+}
+
+// Exhaustive search to update neighbor pointers
+void Triangle::MarkNeighbor(Triangle& t)
+{
+  if (t.Contains(points_[1], points_[2])) {
+    neighbors_[0] = &t;
+    t.MarkNeighbor(points_[1], points_[2], this);
+  } else if (t.Contains(points_[0], points_[2])) {
+    neighbors_[1] = &t;
+    t.MarkNeighbor(points_[0], points_[2], this);
+  } else if (t.Contains(points_[0], points_[1])) {
+    neighbors_[2] = &t;
+    t.MarkNeighbor(points_[0], points_[1], this);
+  }
+}
+
+/**
+ * Clears all references to all other triangles and points
+ */
+void Triangle::Clear()
+{
+    Triangle *t;
+    for (auto& neighbor : neighbors_) {
+      t = neighbor;
+      if (t != nullptr) {
+        t->ClearNeighbor(this);
+      }
+    }
+    ClearNeighbors();
+    points_[0]=points_[1]=points_[2] = nullptr;
+}
+
+void Triangle::ClearNeighbor(const Triangle *triangle )
+{
+    if( neighbors_[0] == triangle )
+    {
+        neighbors_[0] = nullptr;
+    }
+    else if( neighbors_[1] == triangle )
+    {
+        neighbors_[1] = nullptr;
+    }
+    else
+    {
+        neighbors_[2] = nullptr;
+    }
+}
+
+void Triangle::ClearNeighbors()
+{
+  neighbors_[0] = nullptr;
+  neighbors_[1] = nullptr;
+  neighbors_[2] = nullptr;
+}
+
+void Triangle::ClearDelunayEdges()
+{
+  delaunay_edge[0] = delaunay_edge[1] = delaunay_edge[2] = false;
+}
+
+Point* Triangle::OppositePoint(Triangle& t, const Point& p)
+{
+  Point *cw = t.PointCW(p);
+  return PointCW(*cw);
+}
+
+// Legalized triangle by rotating clockwise around point(0)
+void Triangle::Legalize(Point& point)
+{
+  points_[1] = points_[0];
+  points_[0] = points_[2];
+  points_[2] = &point;
+}
+
+// Legalize triagnle by rotating clockwise around oPoint
+void Triangle::Legalize(Point& opoint, Point& npoint)
+{
+  if (&opoint == points_[0]) {
+    points_[1] = points_[0];
+    points_[0] = points_[2];
+    points_[2] = &npoint;
+  } else if (&opoint == points_[1]) {
+    points_[2] = points_[1];
+    points_[1] = points_[0];
+    points_[0] = &npoint;
+  } else if (&opoint == points_[2]) {
+    points_[0] = points_[2];
+    points_[2] = points_[1];
+    points_[1] = &npoint;
+  } else {
+    assert(0);
+  }
+}
+
+int Triangle::Index(const Point* p)
+{
+  if (p == points_[0]) {
+    return 0;
+  } else if (p == points_[1]) {
+    return 1;
+  } else if (p == points_[2]) {
+    return 2;
+  }
+  assert(0);
+  return -1;
+}
+
+int Triangle::EdgeIndex(const Point* p1, const Point* p2)
+{
+  if (points_[0] == p1) {
+    if (points_[1] == p2) {
+      return 2;
+    } else if (points_[2] == p2) {
+      return 1;
+    }
+  } else if (points_[1] == p1) {
+    if (points_[2] == p2) {
+      return 0;
+    } else if (points_[0] == p2) {
+      return 2;
+    }
+  } else if (points_[2] == p1) {
+    if (points_[0] == p2) {
+      return 1;
+    } else if (points_[1] == p2) {
+      return 0;
+    }
+  }
+  return -1;
+}
+
+void Triangle::MarkConstrainedEdge(int index)
+{
+  constrained_edge[index] = true;
+}
+
+void Triangle::MarkConstrainedEdge(Edge& edge)
+{
+  MarkConstrainedEdge(edge.p, edge.q);
+}
+
+// Mark edge as constrained
+void Triangle::MarkConstrainedEdge(Point* p, Point* q)
+{
+  if ((q == points_[0] && p == points_[1]) || (q == points_[1] && p == points_[0])) {
+    constrained_edge[2] = true;
+  } else if ((q == points_[0] && p == points_[2]) || (q == points_[2] && p == points_[0])) {
+    constrained_edge[1] = true;
+  } else if ((q == points_[1] && p == points_[2]) || (q == points_[2] && p == points_[1])) {
+    constrained_edge[0] = true;
+  }
+}
+
+// The point counter-clockwise to given point
+Point* Triangle::PointCW(const Point& point)
+{
+  if (&point == points_[0]) {
+    return points_[2];
+  } else if (&point == points_[1]) {
+    return points_[0];
+  } else if (&point == points_[2]) {
+    return points_[1];
+  }
+  assert(0);
+  return nullptr;
+}
+
+// The point counter-clockwise to given point
+Point* Triangle::PointCCW(const Point& point)
+{
+  if (&point == points_[0]) {
+    return points_[1];
+  } else if (&point == points_[1]) {
+    return points_[2];
+  } else if (&point == points_[2]) {
+    return points_[0];
+  }
+  assert(0);
+  return nullptr;
+}
+
+// The neighbor across to given point
+Triangle* Triangle::NeighborAcross(const Point& point)
+{
+  if (&point == points_[0]) {
+    return neighbors_[0];
+  } else if (&point == points_[1]) {
+    return neighbors_[1];
+  }
+  return neighbors_[2];
+}
+
+// The neighbor clockwise to given point
+Triangle* Triangle::NeighborCW(const Point& point)
+{
+  if (&point == points_[0]) {
+    return neighbors_[1];
+  } else if (&point == points_[1]) {
+    return neighbors_[2];
+  }
+  return neighbors_[0];
+}
+
+// The neighbor counter-clockwise to given point
+Triangle* Triangle::NeighborCCW(const Point& point)
+{
+  if (&point == points_[0]) {
+    return neighbors_[2];
+  } else if (&point == points_[1]) {
+    return neighbors_[0];
+  }
+  return neighbors_[1];
+}
+
+bool Triangle::GetConstrainedEdgeCCW(const Point& p)
+{
+  if (&p == points_[0]) {
+    return constrained_edge[2];
+  } else if (&p == points_[1]) {
+    return constrained_edge[0];
+  }
+  return constrained_edge[1];
+}
+
+bool Triangle::GetConstrainedEdgeCW(const Point& p)
+{
+  if (&p == points_[0]) {
+    return constrained_edge[1];
+  } else if (&p == points_[1]) {
+    return constrained_edge[2];
+  }
+  return constrained_edge[0];
+}
+
+void Triangle::SetConstrainedEdgeCCW(const Point& p, bool ce)
+{
+  if (&p == points_[0]) {
+    constrained_edge[2] = ce;
+  } else if (&p == points_[1]) {
+    constrained_edge[0] = ce;
+  } else {
+    constrained_edge[1] = ce;
+  }
+}
+
+void Triangle::SetConstrainedEdgeCW(const Point& p, bool ce)
+{
+  if (&p == points_[0]) {
+    constrained_edge[1] = ce;
+  } else if (&p == points_[1]) {
+    constrained_edge[2] = ce;
+  } else {
+    constrained_edge[0] = ce;
+  }
+}
+
+bool Triangle::GetDelunayEdgeCCW(const Point& p)
+{
+  if (&p == points_[0]) {
+    return delaunay_edge[2];
+  } else if (&p == points_[1]) {
+    return delaunay_edge[0];
+  }
+  return delaunay_edge[1];
+}
+
+bool Triangle::GetDelunayEdgeCW(const Point& p)
+{
+  if (&p == points_[0]) {
+    return delaunay_edge[1];
+  } else if (&p == points_[1]) {
+    return delaunay_edge[2];
+  }
+  return delaunay_edge[0];
+}
+
+void Triangle::SetDelunayEdgeCCW(const Point& p, bool e)
+{
+  if (&p == points_[0]) {
+    delaunay_edge[2] = e;
+  } else if (&p == points_[1]) {
+    delaunay_edge[0] = e;
+  } else {
+    delaunay_edge[1] = e;
+  }
+}
+
+void Triangle::SetDelunayEdgeCW(const Point& p, bool e)
+{
+  if (&p == points_[0]) {
+    delaunay_edge[1] = e;
+  } else if (&p == points_[1]) {
+    delaunay_edge[2] = e;
+  } else {
+    delaunay_edge[0] = e;
+  }
+}
+
+void Triangle::DebugPrint()
+{
+  std::cout << *points_[0] << " " << *points_[1] << " " << *points_[2] << std::endl;
+}
+
+bool Triangle::CircumcicleContains(const Point& point) const
+{
+  assert(IsCounterClockwise());
+  const double dx = points_[0]->x - point.x;
+  const double dy = points_[0]->y - point.y;
+  const double ex = points_[1]->x - point.x;
+  const double ey = points_[1]->y - point.y;
+  const double fx = points_[2]->x - point.x;
+  const double fy = points_[2]->y - point.y;
+
+  const double ap = dx * dx + dy * dy;
+  const double bp = ex * ex + ey * ey;
+  const double cp = fx * fx + fy * fy;
+
+  return (dx * (fy * bp - cp * ey) - dy * (fx * bp - cp * ex) + ap * (fx * ey - fy * ex)) < 0;
+}
+
+bool Triangle::IsCounterClockwise() const
+{
+  return (points_[1]->x - points_[0]->x) * (points_[2]->y - points_[0]->y) -
+             (points_[2]->x - points_[0]->x) * (points_[1]->y - points_[0]->y) >
+         0;
+}
+
+bool IsDelaunay(const std::vector<p2t::Triangle*>& triangles)
+{
+  for (const auto triangle : triangles) {
+    for (const auto other : triangles) {
+      if (triangle == other) {
+        continue;
+      }
+      for (int i = 0; i < 3; ++i) {
+        if (triangle->CircumcicleContains(*other->GetPoint(i))) {
+          return false;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+} // namespace p2t

vendor/assimp/contrib/poly2tri/poly2tri/common/shapes.h

@@ -0,0 +1,332 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "dll_symbol.h"
+
+#include <cmath>
+#include <cstddef>
+#include <stdexcept>
+#include <vector>
+
+#if defined(_WIN32) && defined(_MSC_VER) && !defined(__INTEL_COMPILER)
+#  pragma warning( disable: 4251)
+#endif
+namespace p2t {
+
+struct Edge;
+
+struct P2T_DLL_SYMBOL Point {
+
+  double x, y;
+
+  /// Default constructor does nothing (for performance).
+  Point()
+  {
+    x = 0.0;
+    y = 0.0;
+  }
+
+  /// The edges this point constitutes an upper ending point
+  std::vector<Edge*> edge_list;
+
+  /// Construct using coordinates.
+  Point(double x, double y);
+
+  /// Set this point to all zeros.
+  void set_zero()
+  {
+    x = 0.0;
+    y = 0.0;
+  }
+
+  /// Set this point to some specified coordinates.
+  void set(double x_, double y_)
+  {
+    x = x_;
+    y = y_;
+  }
+
+  /// Negate this point.
+  Point operator -() const
+  {
+    Point v;
+    v.set(-x, -y);
+    return v;
+  }
+
+  /// Add a point to this point.
+  void operator +=(const Point& v)
+  {
+    x += v.x;
+    y += v.y;
+  }
+
+  /// Subtract a point from this point.
+  void operator -=(const Point& v)
+  {
+    x -= v.x;
+    y -= v.y;
+  }
+
+  /// Multiply this point by a scalar.
+  void operator *=(double a)
+  {
+    x *= a;
+    y *= a;
+  }
+
+  /// Get the length of this point (the norm).
+  double Length() const
+  {
+    return sqrt(x * x + y * y);
+  }
+
+  /// Convert this point into a unit point. Returns the Length.
+  double Normalize()
+  {
+    const double len = Length();
+    x /= len;
+    y /= len;
+    return len;
+  }
+
+};
+
+P2T_DLL_SYMBOL std::ostream& operator<<(std::ostream&, const Point&);
+
+// Represents a simple polygon's edge
+struct P2T_DLL_SYMBOL Edge {
+
+  Point* p, *q;
+
+  /// Constructor
+  Edge(Point& p1, Point& p2) : p(&p1), q(&p2)
+  {
+    if (p1.y > p2.y) {
+      q = &p1;
+      p = &p2;
+    } else if (p1.y == p2.y) {
+      if (p1.x > p2.x) {
+        q = &p1;
+        p = &p2;
+      } else if (p1.x == p2.x) {
+        // Repeat points
+        throw std::runtime_error("Edge::Edge: p1 == p2");
+      }
+    }
+
+    q->edge_list.push_back(this);
+  }
+};
+
+// Triangle-based data structures are know to have better performance than quad-edge structures
+// See: J. Shewchuk, "Triangle: Engineering a 2D Quality Mesh Generator and Delaunay Triangulator"
+//      "Triangulations in CGAL"
+class P2T_DLL_SYMBOL Triangle {
+public:
+
+/// Constructor
+Triangle(Point& a, Point& b, Point& c);
+
+/// Flags to determine if an edge is a Constrained edge
+bool constrained_edge[3];
+/// Flags to determine if an edge is a Delauney edge
+bool delaunay_edge[3];
+
+Point* GetPoint(int index);
+Point* PointCW(const Point& point);
+Point* PointCCW(const Point& point);
+Point* OppositePoint(Triangle& t, const Point& p);
+
+Triangle* GetNeighbor(int index);
+void MarkNeighbor(Point* p1, Point* p2, Triangle* t);
+void MarkNeighbor(Triangle& t);
+
+void MarkConstrainedEdge(int index);
+void MarkConstrainedEdge(Edge& edge);
+void MarkConstrainedEdge(Point* p, Point* q);
+
+int Index(const Point* p);
+int EdgeIndex(const Point* p1, const Point* p2);
+
+Triangle* NeighborAcross(const Point& point);
+Triangle* NeighborCW(const Point& point);
+Triangle* NeighborCCW(const Point& point);
+bool GetConstrainedEdgeCCW(const Point& p);
+bool GetConstrainedEdgeCW(const Point& p);
+void SetConstrainedEdgeCCW(const Point& p, bool ce);
+void SetConstrainedEdgeCW(const Point& p, bool ce);
+bool GetDelunayEdgeCCW(const Point& p);
+bool GetDelunayEdgeCW(const Point& p);
+void SetDelunayEdgeCCW(const Point& p, bool e);
+void SetDelunayEdgeCW(const Point& p, bool e);
+
+bool Contains(const Point* p);
+bool Contains(const Edge& e);
+bool Contains(const Point* p, const Point* q);
+void Legalize(Point& point);
+void Legalize(Point& opoint, Point& npoint);
+/**
+ * Clears all references to all other triangles and points
+ */
+void Clear();
+void ClearNeighbor(const Triangle *triangle);
+void ClearNeighbors();
+void ClearDelunayEdges();
+
+inline bool IsInterior();
+inline void IsInterior(bool b);
+
+void DebugPrint();
+
+bool CircumcicleContains(const Point&) const;
+
+private:
+
+bool IsCounterClockwise() const;
+
+/// Triangle points
+Point* points_[3];
+/// Neighbor list
+Triangle* neighbors_[3];
+
+/// Has this triangle been marked as an interior triangle?
+bool interior_;
+};
+
+inline bool cmp(const Point* a, const Point* b)
+{
+  if (a->y < b->y) {
+    return true;
+  } else if (a->y == b->y) {
+    // Make sure q is point with greater x value
+    if (a->x < b->x) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/// Add two points_ component-wise.
+inline Point operator +(const Point& a, const Point& b)
+{
+  return Point(a.x + b.x, a.y + b.y);
+}
+
+/// Subtract two points_ component-wise.
+inline Point operator -(const Point& a, const Point& b)
+{
+  return Point(a.x - b.x, a.y - b.y);
+}
+
+/// Multiply point by scalar
+inline Point operator *(double s, const Point& a)
+{
+  return Point(s * a.x, s * a.y);
+}
+
+inline bool operator ==(const Point& a, const Point& b)
+{
+  return a.x == b.x && a.y == b.y;
+}
+
+inline bool operator !=(const Point& a, const Point& b)
+{
+  return !(a.x == b.x) || !(a.y == b.y);
+}
+
+/// Peform the dot product on two vectors.
+inline double Dot(const Point& a, const Point& b)
+{
+  return a.x * b.x + a.y * b.y;
+}
+
+/// Perform the cross product on two vectors. In 2D this produces a scalar.
+inline double Cross(const Point& a, const Point& b)
+{
+  return a.x * b.y - a.y * b.x;
+}
+
+/// Perform the cross product on a point and a scalar. In 2D this produces
+/// a point.
+inline Point Cross(const Point& a, double s)
+{
+  return Point(s * a.y, -s * a.x);
+}
+
+/// Perform the cross product on a scalar and a point. In 2D this produces
+/// a point.
+inline Point Cross(double s, const Point& a)
+{
+  return Point(-s * a.y, s * a.x);
+}
+
+inline Point* Triangle::GetPoint(int index)
+{
+  return points_[index];
+}
+
+inline Triangle* Triangle::GetNeighbor(int index)
+{
+  return neighbors_[index];
+}
+
+inline bool Triangle::Contains(const Point* p)
+{
+  return p == points_[0] || p == points_[1] || p == points_[2];
+}
+
+inline bool Triangle::Contains(const Edge& e)
+{
+  return Contains(e.p) && Contains(e.q);
+}
+
+inline bool Triangle::Contains(const Point* p, const Point* q)
+{
+  return Contains(p) && Contains(q);
+}
+
+inline bool Triangle::IsInterior()
+{
+  return interior_;
+}
+
+inline void Triangle::IsInterior(bool b)
+{
+  interior_ = b;
+}
+
+/// Is this set a valid delaunay triangulation?
+P2T_DLL_SYMBOL bool IsDelaunay(const std::vector<p2t::Triangle*>&);
+
+}

vendor/assimp/contrib/poly2tri/poly2tri/common/utils.h

@@ -0,0 +1,130 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+// Otherwise #defines like M_PI are undeclared under Visual Studio
+#define _USE_MATH_DEFINES
+
+#include "shapes.h"
+
+#include <cmath>
+#include <exception>
+
+// C99 removes M_PI from math.h
+#ifndef M_PI
+#define M_PI 3.14159265358979323846264338327
+#endif
+
+namespace p2t {
+
+const double PI_3div4 = 3 * M_PI / 4;
+const double PI_div2 = 1.57079632679489661923;
+const double EPSILON = 1e-12;
+
+enum Orientation { CW, CCW, COLLINEAR };
+
+/**
+ * Forumla to calculate signed area<br>
+ * Positive if CCW<br>
+ * Negative if CW<br>
+ * 0 if collinear<br>
+ * <pre>
+ * A[P1,P2,P3]  =  (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
+ *              =  (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
+ * </pre>
+ */
+Orientation Orient2d(const Point& pa, const Point& pb, const Point& pc)
+{
+  double detleft = (pa.x - pc.x) * (pb.y - pc.y);
+  double detright = (pa.y - pc.y) * (pb.x - pc.x);
+  double val = detleft - detright;
+
+// Using a tolerance here fails on concave-by-subepsilon boundaries
+//   if (val > -EPSILON && val < EPSILON) {
+// Using == on double makes -Wfloat-equal warnings yell at us
+  if (std::fpclassify(val) == FP_ZERO) {
+    return COLLINEAR;
+  } else if (val > 0) {
+    return CCW;
+  }
+  return CW;
+}
+
+/*
+bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
+{
+  double pdx = pd.x;
+  double pdy = pd.y;
+  double adx = pa.x - pdx;
+  double ady = pa.y - pdy;
+  double bdx = pb.x - pdx;
+  double bdy = pb.y - pdy;
+
+  double adxbdy = adx * bdy;
+  double bdxady = bdx * ady;
+  double oabd = adxbdy - bdxady;
+
+  if (oabd <= EPSILON) {
+    return false;
+  }
+
+  double cdx = pc.x - pdx;
+  double cdy = pc.y - pdy;
+
+  double cdxady = cdx * ady;
+  double adxcdy = adx * cdy;
+  double ocad = cdxady - adxcdy;
+
+  if (ocad <= EPSILON) {
+    return false;
+  }
+
+  return true;
+}
+
+*/
+
+bool InScanArea(const Point& pa, const Point& pb, const Point& pc, const Point& pd)
+{
+  double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
+  if (oadb >= -EPSILON) {
+    return false;
+  }
+
+  double oadc = (pa.x - pc.x)*(pd.y - pc.y) - (pd.x - pc.x)*(pa.y - pc.y);
+  if (oadc <= EPSILON) {
+    return false;
+  }
+  return true;
+}
+
+}

vendor/assimp/contrib/poly2tri/poly2tri/poly2tri.h

@@ -0,0 +1,35 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "common/shapes.h"
+#include "sweep/cdt.h"

vendor/assimp/contrib/poly2tri/poly2tri/sweep/advancing_front.cc

@@ -0,0 +1,110 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "advancing_front.h"
+
+#include <cassert>
+
+namespace p2t {
+
+AdvancingFront::AdvancingFront(Node& head, Node& tail)
+{
+  head_ = &head;
+  tail_ = &tail;
+  search_node_ = &head;
+}
+
+Node* AdvancingFront::LocateNode(double x)
+{
+  Node* node = search_node_;
+
+  if (x < node->value) {
+    while ((node = node->prev) != nullptr) {
+      if (x >= node->value) {
+        search_node_ = node;
+        return node;
+      }
+    }
+  } else {
+    while ((node = node->next) != nullptr) {
+      if (x < node->value) {
+        search_node_ = node->prev;
+        return node->prev;
+      }
+    }
+  }
+  return nullptr;
+}
+
+Node* AdvancingFront::FindSearchNode(double x)
+{
+  (void)x; // suppress compiler warnings "unused parameter 'x'"
+  // TODO: implement BST index
+  return search_node_;
+}
+
+Node* AdvancingFront::LocatePoint(const Point* point)
+{
+  const double px = point->x;
+  Node* node = FindSearchNode(px);
+  const double nx = node->point->x;
+
+  if (px == nx) {
+    if (point != node->point) {
+      // We might have two nodes with same x value for a short time
+      if (point == node->prev->point) {
+        node = node->prev;
+      } else if (point == node->next->point) {
+        node = node->next;
+      } else {
+        assert(0);
+      }
+    }
+  } else if (px < nx) {
+    while ((node = node->prev) != nullptr) {
+      if (point == node->point) {
+        break;
+      }
+    }
+  } else {
+    while ((node = node->next) != nullptr) {
+      if (point == node->point)
+        break;
+    }
+  }
+  if(node) search_node_ = node;
+  return node;
+}
+
+AdvancingFront::~AdvancingFront()
+{
+}
+
+} // namespace p2t

vendor/assimp/contrib/poly2tri/poly2tri/sweep/advancing_front.h

@@ -0,0 +1,115 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "../common/shapes.h"
+
+namespace p2t {
+
+struct Node;
+
+// Advancing front node
+struct Node {
+  Point* point;
+  Triangle* triangle;
+
+  Node* next;
+  Node* prev;
+
+  double value;
+
+  Node(Point& p) : point(&p), triangle(NULL), next(NULL), prev(NULL), value(p.x)
+  {
+  }
+
+  Node(Point& p, Triangle& t) : point(&p), triangle(&t), next(NULL), prev(NULL), value(p.x)
+  {
+  }
+
+};
+
+// Advancing front
+class AdvancingFront {
+public:
+
+AdvancingFront(Node& head, Node& tail);
+// Destructor
+~AdvancingFront();
+
+Node* head();
+void set_head(Node* node);
+Node* tail();
+void set_tail(Node* node);
+Node* search();
+void set_search(Node* node);
+
+/// Locate insertion point along advancing front
+Node* LocateNode(double x);
+
+Node* LocatePoint(const Point* point);
+
+private:
+
+Node* head_, *tail_, *search_node_;
+
+Node* FindSearchNode(double x);
+};
+
+inline Node* AdvancingFront::head()
+{
+  return head_;
+}
+inline void AdvancingFront::set_head(Node* node)
+{
+  head_ = node;
+}
+
+inline Node* AdvancingFront::tail()
+{
+  return tail_;
+}
+inline void AdvancingFront::set_tail(Node* node)
+{
+  tail_ = node;
+}
+
+inline Node* AdvancingFront::search()
+{
+  return search_node_;
+}
+
+inline void AdvancingFront::set_search(Node* node)
+{
+  search_node_ = node;
+}
+
+}

vendor/assimp/contrib/poly2tri/poly2tri/sweep/cdt.cc

@@ -0,0 +1,71 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2021, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "cdt.h"
+
+namespace p2t {
+
+CDT::CDT(const std::vector<Point*>& polyline)
+{
+  sweep_context_ = new SweepContext(polyline);
+  sweep_ = new Sweep;
+}
+
+void CDT::AddHole(const std::vector<Point*>& polyline)
+{
+  sweep_context_->AddHole(polyline);
+}
+
+void CDT::AddPoint(Point* point) {
+  sweep_context_->AddPoint(point);
+}
+
+void CDT::Triangulate()
+{
+  sweep_->Triangulate(*sweep_context_);
+}
+
+std::vector<p2t::Triangle*> CDT::GetTriangles()
+{
+  return sweep_context_->GetTriangles();
+}
+
+std::list<p2t::Triangle*> CDT::GetMap()
+{
+  return sweep_context_->GetMap();
+}
+
+CDT::~CDT()
+{
+  delete sweep_context_;
+  delete sweep_;
+}
+
+} // namespace p2t

vendor/assimp/contrib/poly2tri/poly2tri/sweep/cdt.h

@@ -0,0 +1,104 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "advancing_front.h"
+#include "sweep_context.h"
+#include "sweep.h"
+
+#include "../common/dll_symbol.h"
+
+/**
+ *
+ * @author Mason Green <mason.green@gmail.com>
+ *
+ */
+
+namespace p2t {
+
+class P2T_DLL_SYMBOL CDT
+{
+public:
+
+  /**
+   * Constructor - add polyline with non repeating points
+   *
+   * @param polyline
+   */
+  CDT(const std::vector<Point*>& polyline);
+
+   /**
+   * Destructor - clean up memory
+   */
+  ~CDT();
+
+  /**
+   * Add a hole
+   *
+   * @param polyline
+   */
+  void AddHole(const std::vector<Point*>& polyline);
+
+  /**
+   * Add a steiner point
+   *
+   * @param point
+   */
+  void AddPoint(Point* point);
+
+  /**
+   * Triangulate - do this AFTER you've added the polyline, holes, and Steiner points
+   */
+  void Triangulate();
+
+  /**
+   * Get CDT triangles
+   */
+  std::vector<Triangle*> GetTriangles();
+
+  /**
+   * Get triangle map
+   */
+  std::list<Triangle*> GetMap();
+
+  private:
+
+  /**
+   * Internals
+   */
+
+  SweepContext* sweep_context_;
+  Sweep* sweep_;
+
+};
+
+}

vendor/assimp/contrib/poly2tri/poly2tri/sweep/sweep.cc

@@ -0,0 +1,860 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "sweep.h"
+#include "sweep_context.h"
+#include "advancing_front.h"
+#include "../common/utils.h"
+
+#include <cassert>
+#include <stdexcept>
+
+namespace p2t {
+
+// Triangulate simple polygon with holes
+void Sweep::Triangulate(SweepContext& tcx)
+{
+  tcx.InitTriangulation();
+  tcx.CreateAdvancingFront();
+  // Sweep points; build mesh
+  SweepPoints(tcx);
+  // Clean up
+  FinalizationPolygon(tcx);
+}
+
+void Sweep::SweepPoints(SweepContext& tcx)
+{
+  for (size_t i = 1; i < tcx.point_count(); i++) {
+    Point& point = *tcx.GetPoint(i);
+    Node* node = &PointEvent(tcx, point);
+    for (auto& j : point.edge_list) {
+      EdgeEvent(tcx, j, node);
+    }
+  }
+}
+
+void Sweep::FinalizationPolygon(SweepContext& tcx)
+{
+  // Get an Internal triangle to start with
+  Triangle* t = tcx.front()->head()->next->triangle;
+  Point* p = tcx.front()->head()->next->point;
+  while (t && !t->GetConstrainedEdgeCW(*p)) {
+    t = t->NeighborCCW(*p);
+  }
+
+  // Collect interior triangles constrained by edges
+  if (t) {
+    tcx.MeshClean(*t);
+  }
+}
+
+Node& Sweep::PointEvent(SweepContext& tcx, Point& point)
+{
+  Node* node_ptr = tcx.LocateNode(point);
+  if (!node_ptr || !node_ptr->point || !node_ptr->next || !node_ptr->next->point)
+  {
+    throw std::runtime_error("PointEvent - null node");
+  }
+
+  Node& node = *node_ptr;
+  Node& new_node = NewFrontTriangle(tcx, point, node);
+
+  // Only need to check +epsilon since point never have smaller
+  // x value than node due to how we fetch nodes from the front
+  if (point.x <= node.point->x + EPSILON) {
+    Fill(tcx, node);
+  }
+
+  //tcx.AddNode(new_node);
+
+  FillAdvancingFront(tcx, new_node);
+  return new_node;
+}
+
+void Sweep::EdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
+{
+  tcx.edge_event.constrained_edge = edge;
+  tcx.edge_event.right = (edge->p->x > edge->q->x);
+
+  if (IsEdgeSideOfTriangle(*node->triangle, *edge->p, *edge->q)) {
+    return;
+  }
+
+  // For now we will do all needed filling
+  // TODO: integrate with flip process might give some better performance
+  //       but for now this avoid the issue with cases that needs both flips and fills
+  FillEdgeEvent(tcx, edge, node);
+  EdgeEvent(tcx, *edge->p, *edge->q, node->triangle, *edge->q);
+}
+
+void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangle, Point& point)
+{
+  if (triangle == nullptr) {
+    throw std::runtime_error("EdgeEvent - null triangle");
+  }
+  if (IsEdgeSideOfTriangle(*triangle, ep, eq)) {
+    return;
+  }
+
+  Point* p1 = triangle->PointCCW(point);
+  Orientation o1 = Orient2d(eq, *p1, ep);
+  if (o1 == COLLINEAR) {
+    if (triangle->Contains(&eq, p1)) {
+      triangle->MarkConstrainedEdge(&eq, p1);
+      // We are modifying the constraint maybe it would be better to
+      // not change the given constraint and just keep a variable for the new constraint
+      tcx.edge_event.constrained_edge->q = p1;
+      triangle = triangle->NeighborAcross(point);
+      EdgeEvent(tcx, ep, *p1, triangle, *p1);
+    } else {
+      throw std::runtime_error("EdgeEvent - collinear points not supported");
+    }
+    return;
+  }
+
+  Point* p2 = triangle->PointCW(point);
+  Orientation o2 = Orient2d(eq, *p2, ep);
+  if (o2 == COLLINEAR) {
+    if (triangle->Contains(&eq, p2)) {
+      triangle->MarkConstrainedEdge(&eq, p2);
+      // We are modifying the constraint maybe it would be better to
+      // not change the given constraint and just keep a variable for the new constraint
+      tcx.edge_event.constrained_edge->q = p2;
+      triangle = triangle->NeighborAcross(point);
+      EdgeEvent(tcx, ep, *p2, triangle, *p2);
+    } else {
+      throw std::runtime_error("EdgeEvent - collinear points not supported");
+    }
+    return;
+  }
+
+  if (o1 == o2) {
+    // Need to decide if we are rotating CW or CCW to get to a triangle
+    // that will cross edge
+    if (o1 == CW) {
+      triangle = triangle->NeighborCCW(point);
+    } else {
+      triangle = triangle->NeighborCW(point);
+    }
+    EdgeEvent(tcx, ep, eq, triangle, point);
+  } else {
+    // This triangle crosses constraint so lets flippin start!
+    assert(triangle);
+    FlipEdgeEvent(tcx, ep, eq, triangle, point);
+  }
+}
+
+bool Sweep::IsEdgeSideOfTriangle(Triangle& triangle, Point& ep, Point& eq)
+{
+  const int index = triangle.EdgeIndex(&ep, &eq);
+
+  if (index != -1) {
+    triangle.MarkConstrainedEdge(index);
+    Triangle* t = triangle.GetNeighbor(index);
+    if (t) {
+      t->MarkConstrainedEdge(&ep, &eq);
+    }
+    return true;
+  }
+  return false;
+}
+
+Node& Sweep::NewFrontTriangle(SweepContext& tcx, Point& point, Node& node)
+{
+  Triangle* triangle = new Triangle(point, *node.point, *node.next->point);
+
+  triangle->MarkNeighbor(*node.triangle);
+  tcx.AddToMap(triangle);
+
+  Node* new_node = new Node(point);
+  nodes_.push_back(new_node);
+
+  new_node->next = node.next;
+  new_node->prev = &node;
+  node.next->prev = new_node;
+  node.next = new_node;
+
+  if (!Legalize(tcx, *triangle)) {
+    tcx.MapTriangleToNodes(*triangle);
+  }
+
+  return *new_node;
+}
+
+void Sweep::Fill(SweepContext& tcx, Node& node)
+{
+  Triangle* triangle = new Triangle(*node.prev->point, *node.point, *node.next->point);
+
+  // TODO: should copy the constrained_edge value from neighbor triangles
+  //       for now constrained_edge values are copied during the legalize
+  triangle->MarkNeighbor(*node.prev->triangle);
+  triangle->MarkNeighbor(*node.triangle);
+
+  tcx.AddToMap(triangle);
+
+  // Update the advancing front
+  node.prev->next = node.next;
+  node.next->prev = node.prev;
+
+  // If it was legalized the triangle has already been mapped
+  if (!Legalize(tcx, *triangle)) {
+    tcx.MapTriangleToNodes(*triangle);
+  }
+}
+
+void Sweep::FillAdvancingFront(SweepContext& tcx, Node& n)
+{
+
+  // Fill right holes
+  Node* node = n.next;
+
+  while (node && node->next) {
+    // if HoleAngle exceeds 90 degrees then break.
+    if (LargeHole_DontFill(node)) break;
+    Fill(tcx, *node);
+    node = node->next;
+  }
+
+  // Fill left holes
+  node = n.prev;
+
+  while (node && node->prev) {
+    // if HoleAngle exceeds 90 degrees then break.
+    if (LargeHole_DontFill(node)) break;
+    Fill(tcx, *node);
+    node = node->prev;
+  }
+
+  // Fill right basins
+  if (n.next && n.next->next) {
+    const double angle = BasinAngle(n);
+    if (angle < PI_3div4) {
+      FillBasin(tcx, n);
+    }
+  }
+}
+
+// True if HoleAngle exceeds 90 degrees.
+// LargeHole_DontFill checks if the advancing front has a large hole.
+// A "Large hole" is a triangle formed by a sequence of points in the advancing
+// front where three neighbor points form a triangle.
+// And angle between left-top, bottom, and right-top points is more than 90 degrees.
+// The first part of the algorithm reviews only three neighbor points, e.g. named A, B, C.
+// Additional part of this logic reviews a sequence of 5 points -
+// additionally reviews one point before and one after the sequence of three (A, B, C),
+// e.g. named X and Y.
+// In this case, angles are XBC and ABY and this if angles are negative or more
+// than 90 degrees LargeHole_DontFill returns true.
+// But there is a configuration when ABC has a negative angle but XBC or ABY is less
+// than 90 degrees and positive.
+// Then function LargeHole_DontFill return false and initiates filling.
+// This filling creates a triangle ABC and adds it to the advancing front.
+// But in the case when angle ABC is negative this triangle goes inside the advancing front
+// and can intersect previously created triangles.
+// This triangle leads to making wrong advancing front and problems in triangulation in the future.
+// Looks like such a triangle should not be created.
+// The simplest way to check and fix it is to check an angle ABC.
+// If it is negative LargeHole_DontFill should return true and
+// not initiate creating the ABC triangle in the advancing front.
+// X______A         Y
+//        \        /
+//         \      /
+//          \ B  /
+//           |  /
+//           | /
+//           |/
+//           C
+bool Sweep::LargeHole_DontFill(const Node* node) const {
+
+  const Node* nextNode = node->next;
+  const Node* prevNode = node->prev;
+  if (!AngleExceeds90Degrees(node->point, nextNode->point, prevNode->point))
+          return false;
+
+  if (AngleIsNegative(node->point, nextNode->point, prevNode->point))
+          return true;
+
+  // Check additional points on front.
+  const Node* next2Node = nextNode->next;
+  // "..Plus.." because only want angles on same side as point being added.
+  if ((next2Node != nullptr) && !AngleExceedsPlus90DegreesOrIsNegative(node->point, next2Node->point, prevNode->point))
+          return false;
+
+  const Node* prev2Node = prevNode->prev;
+  // "..Plus.." because only want angles on same side as point being added.
+  if ((prev2Node != nullptr) && !AngleExceedsPlus90DegreesOrIsNegative(node->point, nextNode->point, prev2Node->point))
+          return false;
+
+  return true;
+}
+
+bool Sweep::AngleIsNegative(const Point* origin, const Point* pa, const Point* pb) const {
+    const double angle = Angle(origin, pa, pb);
+    return angle < 0;
+}
+
+bool Sweep::AngleExceeds90Degrees(const Point* origin, const Point* pa, const Point* pb) const {
+  const double angle = Angle(origin, pa, pb);
+  return ((angle > PI_div2) || (angle < -PI_div2));
+}
+
+bool Sweep::AngleExceedsPlus90DegreesOrIsNegative(const Point* origin, const Point* pa, const Point* pb) const {
+  const double angle = Angle(origin, pa, pb);
+  return (angle > PI_div2) || (angle < 0);
+}
+
+double Sweep::Angle(const Point* origin, const Point* pa, const Point* pb) const {
+  /* Complex plane
+   * ab = cosA +i*sinA
+   * ab = (ax + ay*i)(bx + by*i) = (ax*bx + ay*by) + i(ax*by-ay*bx)
+   * atan2(y,x) computes the principal value of the argument function
+   * applied to the complex number x+iy
+   * Where x = ax*bx + ay*by
+   *       y = ax*by - ay*bx
+   */
+  const double px = origin->x;
+  const double py = origin->y;
+  const double ax = pa->x - px;
+  const double ay = pa->y - py;
+  const double bx = pb->x - px;
+  const double by = pb->y - py;
+  const double x = ax * by - ay * bx;
+  const double y = ax * bx + ay * by;
+  return atan2(x, y);
+}
+
+double Sweep::BasinAngle(const Node& node) const
+{
+  const double ax = node.point->x - node.next->next->point->x;
+  const double ay = node.point->y - node.next->next->point->y;
+  return atan2(ay, ax);
+}
+
+double Sweep::HoleAngle(const Node& node) const
+{
+  /* Complex plane
+   * ab = cosA +i*sinA
+   * ab = (ax + ay*i)(bx + by*i) = (ax*bx + ay*by) + i(ax*by-ay*bx)
+   * atan2(y,x) computes the principal value of the argument function
+   * applied to the complex number x+iy
+   * Where x = ax*bx + ay*by
+   *       y = ax*by - ay*bx
+   */
+  const double ax = node.next->point->x - node.point->x;
+  const double ay = node.next->point->y - node.point->y;
+  const double bx = node.prev->point->x - node.point->x;
+  const double by = node.prev->point->y - node.point->y;
+  return atan2(ax * by - ay * bx, ax * bx + ay * by);
+}
+
+bool Sweep::Legalize(SweepContext& tcx, Triangle& t)
+{
+  // To legalize a triangle we start by finding if any of the three edges
+  // violate the Delaunay condition
+  for (int i = 0; i < 3; i++) {
+    if (t.delaunay_edge[i])
+      continue;
+
+    Triangle* ot = t.GetNeighbor(i);
+
+    if (ot) {
+      Point* p = t.GetPoint(i);
+      Point* op = ot->OppositePoint(t, *p);
+      int oi = ot->Index(op);
+
+      // If this is a Constrained Edge or a Delaunay Edge(only during recursive legalization)
+      // then we should not try to legalize
+      if (ot->constrained_edge[oi] || ot->delaunay_edge[oi]) {
+        t.constrained_edge[i] = ot->constrained_edge[oi];
+        continue;
+      }
+
+      bool inside = Incircle(*p, *t.PointCCW(*p), *t.PointCW(*p), *op);
+
+      if (inside) {
+        // Lets mark this shared edge as Delaunay
+        t.delaunay_edge[i] = true;
+        ot->delaunay_edge[oi] = true;
+
+        // Lets rotate shared edge one vertex CW to legalize it
+        RotateTrianglePair(t, *p, *ot, *op);
+
+        // We now got one valid Delaunay Edge shared by two triangles
+        // This gives us 4 new edges to check for Delaunay
+
+        // Make sure that triangle to node mapping is done only one time for a specific triangle
+        bool not_legalized = !Legalize(tcx, t);
+        if (not_legalized) {
+          tcx.MapTriangleToNodes(t);
+        }
+
+        not_legalized = !Legalize(tcx, *ot);
+        if (not_legalized)
+          tcx.MapTriangleToNodes(*ot);
+
+        // Reset the Delaunay edges, since they only are valid Delaunay edges
+        // until we add a new triangle or point.
+        // XXX: need to think about this. Can these edges be tried after we
+        //      return to previous recursive level?
+        t.delaunay_edge[i] = false;
+        ot->delaunay_edge[oi] = false;
+
+        // If triangle have been legalized no need to check the other edges since
+        // the recursive legalization will handles those so we can end here.
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+bool Sweep::Incircle(const Point& pa, const Point& pb, const Point& pc, const Point& pd) const
+{
+  const double adx = pa.x - pd.x;
+  const double ady = pa.y - pd.y;
+  const double bdx = pb.x - pd.x;
+  const double bdy = pb.y - pd.y;
+
+  const double adxbdy = adx * bdy;
+  const double bdxady = bdx * ady;
+  const double oabd = adxbdy - bdxady;
+
+  if (oabd <= 0)
+    return false;
+
+  const double cdx = pc.x - pd.x;
+  const double cdy = pc.y - pd.y;
+
+  const double cdxady = cdx * ady;
+  const double adxcdy = adx * cdy;
+  const double ocad = cdxady - adxcdy;
+
+  if (ocad <= 0)
+    return false;
+
+  const double bdxcdy = bdx * cdy;
+  const double cdxbdy = cdx * bdy;
+
+  const double alift = adx * adx + ady * ady;
+  const double blift = bdx * bdx + bdy * bdy;
+  const double clift = cdx * cdx + cdy * cdy;
+
+  const double det = alift * (bdxcdy - cdxbdy) + blift * ocad + clift * oabd;
+
+  return det > 0;
+}
+
+void Sweep::RotateTrianglePair(Triangle& t, Point& p, Triangle& ot, Point& op) const
+{
+  Triangle* n1, *n2, *n3, *n4;
+  n1 = t.NeighborCCW(p);
+  n2 = t.NeighborCW(p);
+  n3 = ot.NeighborCCW(op);
+  n4 = ot.NeighborCW(op);
+
+  bool ce1, ce2, ce3, ce4;
+  ce1 = t.GetConstrainedEdgeCCW(p);
+  ce2 = t.GetConstrainedEdgeCW(p);
+  ce3 = ot.GetConstrainedEdgeCCW(op);
+  ce4 = ot.GetConstrainedEdgeCW(op);
+
+  bool de1, de2, de3, de4;
+  de1 = t.GetDelunayEdgeCCW(p);
+  de2 = t.GetDelunayEdgeCW(p);
+  de3 = ot.GetDelunayEdgeCCW(op);
+  de4 = ot.GetDelunayEdgeCW(op);
+
+  t.Legalize(p, op);
+  ot.Legalize(op, p);
+
+  // Remap delaunay_edge
+  ot.SetDelunayEdgeCCW(p, de1);
+  t.SetDelunayEdgeCW(p, de2);
+  t.SetDelunayEdgeCCW(op, de3);
+  ot.SetDelunayEdgeCW(op, de4);
+
+  // Remap constrained_edge
+  ot.SetConstrainedEdgeCCW(p, ce1);
+  t.SetConstrainedEdgeCW(p, ce2);
+  t.SetConstrainedEdgeCCW(op, ce3);
+  ot.SetConstrainedEdgeCW(op, ce4);
+
+  // Remap neighbors
+  // XXX: might optimize the markNeighbor by keeping track of
+  //      what side should be assigned to what neighbor after the
+  //      rotation. Now mark neighbor does lots of testing to find
+  //      the right side.
+  t.ClearNeighbors();
+  ot.ClearNeighbors();
+  if (n1) ot.MarkNeighbor(*n1);
+  if (n2) t.MarkNeighbor(*n2);
+  if (n3) t.MarkNeighbor(*n3);
+  if (n4) ot.MarkNeighbor(*n4);
+  t.MarkNeighbor(ot);
+}
+
+void Sweep::FillBasin(SweepContext& tcx, Node& node)
+{
+  if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
+    tcx.basin.left_node = node.next->next;
+  } else {
+    tcx.basin.left_node = node.next;
+  }
+
+  // Find the bottom and right node
+  tcx.basin.bottom_node = tcx.basin.left_node;
+  while (tcx.basin.bottom_node->next
+         && tcx.basin.bottom_node->point->y >= tcx.basin.bottom_node->next->point->y) {
+    tcx.basin.bottom_node = tcx.basin.bottom_node->next;
+  }
+  if (tcx.basin.bottom_node == tcx.basin.left_node) {
+    // No valid basin
+    return;
+  }
+
+  tcx.basin.right_node = tcx.basin.bottom_node;
+  while (tcx.basin.right_node->next
+         && tcx.basin.right_node->point->y < tcx.basin.right_node->next->point->y) {
+    tcx.basin.right_node = tcx.basin.right_node->next;
+  }
+  if (tcx.basin.right_node == tcx.basin.bottom_node) {
+    // No valid basins
+    return;
+  }
+
+  tcx.basin.width = tcx.basin.right_node->point->x - tcx.basin.left_node->point->x;
+  tcx.basin.left_highest = tcx.basin.left_node->point->y > tcx.basin.right_node->point->y;
+
+  FillBasinReq(tcx, tcx.basin.bottom_node);
+}
+
+void Sweep::FillBasinReq(SweepContext& tcx, Node* node)
+{
+  // if shallow stop filling
+  if (IsShallow(tcx, *node)) {
+    return;
+  }
+
+  Fill(tcx, *node);
+
+  if (node->prev == tcx.basin.left_node && node->next == tcx.basin.right_node) {
+    return;
+  } else if (node->prev == tcx.basin.left_node) {
+    Orientation o = Orient2d(*node->point, *node->next->point, *node->next->next->point);
+    if (o == CW) {
+      return;
+    }
+    node = node->next;
+  } else if (node->next == tcx.basin.right_node) {
+    Orientation o = Orient2d(*node->point, *node->prev->point, *node->prev->prev->point);
+    if (o == CCW) {
+      return;
+    }
+    node = node->prev;
+  } else {
+    // Continue with the neighbor node with lowest Y value
+    if (node->prev->point->y < node->next->point->y) {
+      node = node->prev;
+    } else {
+      node = node->next;
+    }
+  }
+
+  FillBasinReq(tcx, node);
+}
+
+bool Sweep::IsShallow(SweepContext& tcx, Node& node)
+{
+  double height;
+
+  if (tcx.basin.left_highest) {
+    height = tcx.basin.left_node->point->y - node.point->y;
+  } else {
+    height = tcx.basin.right_node->point->y - node.point->y;
+  }
+
+  // if shallow stop filling
+  if (tcx.basin.width > height) {
+    return true;
+  }
+  return false;
+}
+
+void Sweep::FillEdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
+{
+  if (tcx.edge_event.right) {
+    FillRightAboveEdgeEvent(tcx, edge, node);
+  } else {
+    FillLeftAboveEdgeEvent(tcx, edge, node);
+  }
+}
+
+void Sweep::FillRightAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
+{
+  while (node->next->point->x < edge->p->x) {
+    // Check if next node is below the edge
+    if (Orient2d(*edge->q, *node->next->point, *edge->p) == CCW) {
+      FillRightBelowEdgeEvent(tcx, edge, *node);
+    } else {
+      node = node->next;
+    }
+  }
+}
+
+void Sweep::FillRightBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
+{
+  if (node.point->x < edge->p->x) {
+    if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
+      // Concave
+      FillRightConcaveEdgeEvent(tcx, edge, node);
+    } else {
+      // Convex
+      FillRightConvexEdgeEvent(tcx, edge, node);
+      // Retry this one
+      FillRightBelowEdgeEvent(tcx, edge, node);
+    }
+  }
+}
+
+void Sweep::FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
+{
+  Fill(tcx, *node.next);
+  if (node.next->point != edge->p) {
+    // Next above or below edge?
+    if (Orient2d(*edge->q, *node.next->point, *edge->p) == CCW) {
+      // Below
+      if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
+        // Next is concave
+        FillRightConcaveEdgeEvent(tcx, edge, node);
+      } else {
+        // Next is convex
+      }
+    }
+  }
+}
+
+void Sweep::FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
+{
+  // Next concave or convex?
+  if (Orient2d(*node.next->point, *node.next->next->point, *node.next->next->next->point) == CCW) {
+    // Concave
+    FillRightConcaveEdgeEvent(tcx, edge, *node.next);
+  } else {
+    // Convex
+    // Next above or below edge?
+    if (Orient2d(*edge->q, *node.next->next->point, *edge->p) == CCW) {
+      // Below
+      FillRightConvexEdgeEvent(tcx, edge, *node.next);
+    } else {
+      // Above
+    }
+  }
+}
+
+void Sweep::FillLeftAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
+{
+  while (node->prev->point->x > edge->p->x) {
+    // Check if next node is below the edge
+    if (Orient2d(*edge->q, *node->prev->point, *edge->p) == CW) {
+      FillLeftBelowEdgeEvent(tcx, edge, *node);
+    } else {
+      node = node->prev;
+    }
+  }
+}
+
+void Sweep::FillLeftBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
+{
+  if (node.point->x > edge->p->x) {
+    if (Orient2d(*node.point, *node.prev->point, *node.prev->prev->point) == CW) {
+      // Concave
+      FillLeftConcaveEdgeEvent(tcx, edge, node);
+    } else {
+      // Convex
+      FillLeftConvexEdgeEvent(tcx, edge, node);
+      // Retry this one
+      FillLeftBelowEdgeEvent(tcx, edge, node);
+    }
+  }
+}
+
+void Sweep::FillLeftConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
+{
+  // Next concave or convex?
+  if (Orient2d(*node.prev->point, *node.prev->prev->point, *node.prev->prev->prev->point) == CW) {
+    // Concave
+    FillLeftConcaveEdgeEvent(tcx, edge, *node.prev);
+  } else {
+    // Convex
+    // Next above or below edge?
+    if (Orient2d(*edge->q, *node.prev->prev->point, *edge->p) == CW) {
+      // Below
+      FillLeftConvexEdgeEvent(tcx, edge, *node.prev);
+    } else {
+      // Above
+    }
+  }
+}
+
+void Sweep::FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
+{
+  Fill(tcx, *node.prev);
+  if (node.prev->point != edge->p) {
+    // Next above or below edge?
+    if (Orient2d(*edge->q, *node.prev->point, *edge->p) == CW) {
+      // Below
+      if (Orient2d(*node.point, *node.prev->point, *node.prev->prev->point) == CW) {
+        // Next is concave
+        FillLeftConcaveEdgeEvent(tcx, edge, node);
+      } else {
+        // Next is convex
+      }
+    }
+  }
+}
+
+void Sweep::FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p)
+{
+  assert(t);
+  Triangle* ot_ptr = t->NeighborAcross(p);
+  if (ot_ptr == nullptr)
+  {
+    throw std::runtime_error("FlipEdgeEvent - null neighbor across");
+  }
+  Triangle& ot = *ot_ptr;
+  Point& op = *ot.OppositePoint(*t, p);
+
+  if (InScanArea(p, *t->PointCCW(p), *t->PointCW(p), op)) {
+    // Lets rotate shared edge one vertex CW
+    RotateTrianglePair(*t, p, ot, op);
+    tcx.MapTriangleToNodes(*t);
+    tcx.MapTriangleToNodes(ot);
+
+    if (p == eq && op == ep) {
+      if (eq == *tcx.edge_event.constrained_edge->q && ep == *tcx.edge_event.constrained_edge->p) {
+        t->MarkConstrainedEdge(&ep, &eq);
+        ot.MarkConstrainedEdge(&ep, &eq);
+        Legalize(tcx, *t);
+        Legalize(tcx, ot);
+      } else {
+        // XXX: I think one of the triangles should be legalized here?
+      }
+    } else {
+      Orientation o = Orient2d(eq, op, ep);
+      t = &NextFlipTriangle(tcx, (int)o, *t, ot, p, op);
+      FlipEdgeEvent(tcx, ep, eq, t, p);
+    }
+  } else {
+    Point& newP = NextFlipPoint(ep, eq, ot, op);
+    FlipScanEdgeEvent(tcx, ep, eq, *t, ot, newP);
+    EdgeEvent(tcx, ep, eq, t, p);
+  }
+}
+
+Triangle& Sweep::NextFlipTriangle(SweepContext& tcx, int o, Triangle& t, Triangle& ot, Point& p, Point& op)
+{
+  if (o == CCW) {
+    // ot is not crossing edge after flip
+    int edge_index = ot.EdgeIndex(&p, &op);
+    ot.delaunay_edge[edge_index] = true;
+    Legalize(tcx, ot);
+    ot.ClearDelunayEdges();
+    return t;
+  }
+
+  // t is not crossing edge after flip
+  int edge_index = t.EdgeIndex(&p, &op);
+
+  t.delaunay_edge[edge_index] = true;
+  Legalize(tcx, t);
+  t.ClearDelunayEdges();
+  return ot;
+}
+
+Point& Sweep::NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op)
+{
+  Orientation o2d = Orient2d(eq, op, ep);
+  if (o2d == CW) {
+    // Right
+    return *ot.PointCCW(op);
+  } else if (o2d == CCW) {
+    // Left
+    return *ot.PointCW(op);
+  }
+  throw std::runtime_error("[Unsupported] Opposing point on constrained edge");
+}
+
+void Sweep::FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle,
+                              Triangle& t, Point& p)
+{
+  Triangle* ot_ptr = t.NeighborAcross(p);
+  if (ot_ptr == nullptr) {
+    throw std::runtime_error("FlipScanEdgeEvent - null neighbor across");
+  }
+
+  Point* op_ptr = ot_ptr->OppositePoint(t, p);
+  if (op_ptr == nullptr) {
+    throw std::runtime_error("FlipScanEdgeEvent - null opposing point");
+  }
+
+  Point* p1 = flip_triangle.PointCCW(eq);
+  Point* p2 = flip_triangle.PointCW(eq);
+  if (p1 == nullptr || p2 == nullptr) {
+    throw std::runtime_error("FlipScanEdgeEvent - null on either of points");
+  }
+
+  Triangle& ot = *ot_ptr;
+  Point& op = *op_ptr;
+
+  if (InScanArea(eq, *p1, *p2, op)) {
+    // flip with new edge op->eq
+    FlipEdgeEvent(tcx, eq, op, &ot, op);
+    // TODO: Actually I just figured out that it should be possible to
+    //       improve this by getting the next ot and op before the the above
+    //       flip and continue the flipScanEdgeEvent here
+    // set new ot and op here and loop back to inScanArea test
+    // also need to set a new flip_triangle first
+    // Turns out at first glance that this is somewhat complicated
+    // so it will have to wait.
+  } else {
+    Point& newP = NextFlipPoint(ep, eq, ot, op);
+    FlipScanEdgeEvent(tcx, ep, eq, flip_triangle, ot, newP);
+  }
+}
+
+Sweep::~Sweep() {
+
+    // Clean up memory
+    for (auto& node : nodes_) {
+      delete node;
+    }
+}
+
+} // namespace p2t

vendor/assimp/contrib/poly2tri/poly2tri/sweep/sweep.h

@@ -0,0 +1,283 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/**
+ * Sweep-line, Constrained Delauney Triangulation (CDT) See: Domiter, V. and
+ * Zalik, B.(2008)'Sweep-line algorithm for constrained Delaunay triangulation',
+ * International Journal of Geographical Information Science
+ *
+ * "FlipScan" Constrained Edge Algorithm invented by Thomas Åhlén, thahlen@gmail.com
+ */
+
+#pragma once
+
+#include <vector>
+
+namespace p2t {
+
+class SweepContext;
+struct Node;
+struct Point;
+struct Edge;
+class Triangle;
+
+class Sweep
+{
+public:
+
+  /**
+   * Triangulate
+   *
+   * @param tcx
+   */
+  void Triangulate(SweepContext& tcx);
+
+  /**
+   * Destructor - clean up memory
+   */
+  ~Sweep();
+
+private:
+
+  /**
+   * Start sweeping the Y-sorted point set from bottom to top
+   *
+   * @param tcx
+   */
+  void SweepPoints(SweepContext& tcx);
+
+  /**
+   * Find closes node to the left of the new point and
+   * create a new triangle. If needed new holes and basins
+   * will be filled to.
+   *
+   * @param tcx
+   * @param point
+   * @return
+   */
+  Node& PointEvent(SweepContext& tcx, Point& point);
+
+   /**
+     *
+     *
+     * @param tcx
+     * @param edge
+     * @param node
+     */
+  void EdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
+
+  void EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangle, Point& point);
+
+  /**
+   * Creates a new front triangle and legalize it
+   *
+   * @param tcx
+   * @param point
+   * @param node
+   * @return
+   */
+  Node& NewFrontTriangle(SweepContext& tcx, Point& point, Node& node);
+
+  /**
+   * Adds a triangle to the advancing front to fill a hole.
+   * @param tcx
+   * @param node - middle node, that is the bottom of the hole
+   */
+  void Fill(SweepContext& tcx, Node& node);
+
+  /**
+   * Returns true if triangle was legalized
+   */
+  bool Legalize(SweepContext& tcx, Triangle& t);
+
+  /**
+   * <b>Requirement</b>:<br>
+   * 1. a,b and c form a triangle.<br>
+   * 2. a and d is know to be on opposite side of bc<br>
+   * <pre>
+   *                a
+   *                +
+   *               / \
+   *              /   \
+   *            b/     \c
+   *            +-------+
+   *           /    d    \
+   *          /           \
+   * </pre>
+   * <b>Fact</b>: d has to be in area B to have a chance to be inside the circle formed by
+   *  a,b and c<br>
+   *  d is outside B if orient2d(a,b,d) or orient2d(c,a,d) is CW<br>
+   *  This preknowledge gives us a way to optimize the incircle test
+   * @param a - triangle point, opposite d
+   * @param b - triangle point
+   * @param c - triangle point
+   * @param d - point opposite a
+   * @return true if d is inside circle, false if on circle edge
+   */
+  bool Incircle(const Point& pa, const Point& pb, const Point& pc, const Point& pd) const;
+
+  /**
+   * Rotates a triangle pair one vertex CW
+   *<pre>
+   *       n2                    n2
+   *  P +-----+             P +-----+
+   *    | t  /|               |\  t |
+   *    |   / |               | \   |
+   *  n1|  /  |n3           n1|  \  |n3
+   *    | /   |    after CW   |   \ |
+   *    |/ oT |               | oT \|
+   *    +-----+ oP            +-----+
+   *       n4                    n4
+   * </pre>
+   */
+  void RotateTrianglePair(Triangle& t, Point& p, Triangle& ot, Point& op) const;
+
+  /**
+   * Fills holes in the Advancing Front
+   *
+   *
+   * @param tcx
+   * @param n
+   */
+  void FillAdvancingFront(SweepContext& tcx, Node& n);
+
+  // Decision-making about when to Fill hole.
+  // Contributed by ToolmakerSteve2
+  bool LargeHole_DontFill(const Node* node) const;
+  bool AngleIsNegative(const Point* origin, const Point* pa, const Point* pb) const;
+  bool AngleExceeds90Degrees(const Point* origin, const Point* pa, const Point* pb) const;
+  bool AngleExceedsPlus90DegreesOrIsNegative(const Point* origin, const Point* pa, const Point* pb) const;
+  double Angle(const Point* origin, const Point* pa, const Point* pb) const;
+
+  /**
+   *
+   * @param node - middle node
+   * @return the angle between 3 front nodes
+   */
+  double HoleAngle(const Node& node) const;
+
+  /**
+   * The basin angle is decided against the horizontal line [1,0]
+   */
+  double BasinAngle(const Node& node) const;
+
+  /**
+   * Fills a basin that has formed on the Advancing Front to the right
+   * of given node.<br>
+   * First we decide a left,bottom and right node that forms the
+   * boundaries of the basin. Then we do a reqursive fill.
+   *
+   * @param tcx
+   * @param node - starting node, this or next node will be left node
+   */
+  void FillBasin(SweepContext& tcx, Node& node);
+
+  /**
+   * Recursive algorithm to fill a Basin with triangles
+   *
+   * @param tcx
+   * @param node - bottom_node
+   * @param cnt - counter used to alternate on even and odd numbers
+   */
+  void FillBasinReq(SweepContext& tcx, Node* node);
+
+  bool IsShallow(SweepContext& tcx, Node& node);
+
+  bool IsEdgeSideOfTriangle(Triangle& triangle, Point& ep, Point& eq);
+
+  void FillEdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
+
+  void FillRightAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
+
+  void FillRightBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
+
+  void FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
+
+  void FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
+
+  void FillLeftAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
+
+  void FillLeftBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
+
+  void FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
+
+  void FillLeftConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
+
+  void FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p);
+
+  /**
+   * After a flip we have two triangles and know that only one will still be
+   * intersecting the edge. So decide which to contiune with and legalize the other
+   *
+   * @param tcx
+   * @param o - should be the result of an orient2d( eq, op, ep )
+   * @param t - triangle 1
+   * @param ot - triangle 2
+   * @param p - a point shared by both triangles
+   * @param op - another point shared by both triangles
+   * @return returns the triangle still intersecting the edge
+   */
+  Triangle& NextFlipTriangle(SweepContext& tcx, int o, Triangle&  t, Triangle& ot, Point& p, Point& op);
+
+   /**
+     * When we need to traverse from one triangle to the next we need
+     * the point in current triangle that is the opposite point to the next
+     * triangle.
+     *
+     * @param ep
+     * @param eq
+     * @param ot
+     * @param op
+     * @return
+     */
+  Point& NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op);
+
+   /**
+     * Scan part of the FlipScan algorithm<br>
+     * When a triangle pair isn't flippable we will scan for the next
+     * point that is inside the flip triangle scan area. When found
+     * we generate a new flipEdgeEvent
+     *
+     * @param tcx
+     * @param ep - last point on the edge we are traversing
+     * @param eq - first point on the edge we are traversing
+     * @param flipTriangle - the current triangle sharing the point eq with edge
+     * @param t
+     * @param p
+     */
+  void FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle, Triangle& t, Point& p);
+
+  void FinalizationPolygon(SweepContext& tcx);
+
+  std::vector<Node*> nodes_;
+
+};
+
+}

vendor/assimp/contrib/poly2tri/poly2tri/sweep/sweep_context.cc

@@ -0,0 +1,206 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2022, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "sweep_context.h"
+#include <algorithm>
+#include "advancing_front.h"
+
+namespace p2t {
+
+SweepContext::SweepContext(std::vector<Point*> polyline) : points_(std::move(polyline)),
+  front_(nullptr),
+  head_(nullptr),
+  tail_(nullptr),
+  af_head_(nullptr),
+  af_middle_(nullptr),
+  af_tail_(nullptr)
+{
+  InitEdges(points_);
+}
+
+void SweepContext::AddHole(const std::vector<Point*>& polyline)
+{
+  InitEdges(polyline);
+  for (auto i : polyline) {
+    points_.push_back(i);
+  }
+}
+
+void SweepContext::AddPoint(Point* point) {
+  points_.push_back(point);
+}
+
+std::vector<Triangle*> &SweepContext::GetTriangles()
+{
+  return triangles_;
+}
+
+std::list<Triangle*> &SweepContext::GetMap()
+{
+  return map_;
+}
+
+void SweepContext::InitTriangulation()
+{
+  double xmax(points_[0]->x), xmin(points_[0]->x);
+  double ymax(points_[0]->y), ymin(points_[0]->y);
+
+  // Calculate bounds.
+  for (auto& point : points_) {
+    Point& p = *point;
+    if (p.x > xmax)
+      xmax = p.x;
+    if (p.x < xmin)
+      xmin = p.x;
+    if (p.y > ymax)
+      ymax = p.y;
+    if (p.y < ymin)
+      ymin = p.y;
+  }
+
+  double dx = kAlpha * (xmax - xmin);
+  double dy = kAlpha * (ymax - ymin);
+  head_ = new Point(xmin - dx, ymin - dy);
+  tail_ = new Point(xmax + dx, ymin - dy);
+
+  // Sort points along y-axis
+  std::sort(points_.begin(), points_.end(), cmp);
+
+}
+
+void SweepContext::InitEdges(const std::vector<Point*>& polyline)
+{
+  size_t num_points = polyline.size();
+  for (size_t i = 0; i < num_points; i++) {
+    size_t j = i < num_points - 1 ? i + 1 : 0;
+    edge_list.push_back(new Edge(*polyline[i], *polyline[j]));
+  }
+}
+
+Point* SweepContext::GetPoint(size_t index)
+{
+  return points_[index];
+}
+
+void SweepContext::AddToMap(Triangle* triangle)
+{
+  map_.push_back(triangle);
+}
+
+Node* SweepContext::LocateNode(const Point& point)
+{
+  // TODO implement search tree
+  return front_->LocateNode(point.x);
+}
+
+void SweepContext::CreateAdvancingFront()
+{
+
+  // Initial triangle
+  Triangle* triangle = new Triangle(*points_[0], *head_, *tail_);
+
+  map_.push_back(triangle);
+
+  af_head_ = new Node(*triangle->GetPoint(1), *triangle);
+  af_middle_ = new Node(*triangle->GetPoint(0), *triangle);
+  af_tail_ = new Node(*triangle->GetPoint(2));
+  front_ = new AdvancingFront(*af_head_, *af_tail_);
+
+  // TODO: More intuitive if head is middles next and not previous?
+  //       so swap head and tail
+  af_head_->next = af_middle_;
+  af_middle_->next = af_tail_;
+  af_middle_->prev = af_head_;
+  af_tail_->prev = af_middle_;
+}
+
+void SweepContext::RemoveNode(Node* node)
+{
+  delete node;
+}
+
+void SweepContext::MapTriangleToNodes(Triangle& t)
+{
+  for (int i = 0; i < 3; i++) {
+    if (!t.GetNeighbor(i)) {
+      Node* n = front_->LocatePoint(t.PointCW(*t.GetPoint(i)));
+      if (n)
+        n->triangle = &t;
+    }
+  }
+}
+
+void SweepContext::RemoveFromMap(Triangle* triangle)
+{
+  map_.remove(triangle);
+}
+
+void SweepContext::MeshClean(Triangle& triangle)
+{
+  std::vector<Triangle *> triangles;
+  triangles.push_back(&triangle);
+
+  while(!triangles.empty()){
+	Triangle *t = triangles.back();
+	triangles.pop_back();
+
+    if (t != nullptr && !t->IsInterior()) {
+      t->IsInterior(true);
+      triangles_.push_back(t);
+      for (int i = 0; i < 3; i++) {
+        if (!t->constrained_edge[i])
+          triangles.push_back(t->GetNeighbor(i));
+      }
+    }
+  }
+}
+
+SweepContext::~SweepContext()
+{
+
+    // Clean up memory
+
+    delete head_;
+    delete tail_;
+    delete front_;
+    delete af_head_;
+    delete af_middle_;
+    delete af_tail_;
+
+    for (auto ptr : map_) {
+      delete ptr;
+    }
+
+    for (auto& i : edge_list) {
+      delete i;
+    }
+}
+
+} // namespace p2t

vendor/assimp/contrib/poly2tri/poly2tri/sweep/sweep_context.h

@@ -0,0 +1,184 @@
+/*
+ * Poly2Tri Copyright (c) 2009-2022, Poly2Tri Contributors
+ * https://github.com/jhasse/poly2tri
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * * Neither the name of Poly2Tri nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without specific
+ *   prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <list>
+#include <vector>
+#include <cstddef>
+
+namespace p2t {
+
+// Inital triangle factor, seed triangle will extend 30% of
+// PointSet width to both left and right.
+const double kAlpha = 0.3;
+
+struct Point;
+class Triangle;
+struct Node;
+struct Edge;
+class AdvancingFront;
+
+class SweepContext {
+public:
+
+/// Constructor
+explicit SweepContext(std::vector<Point*> polyline);
+/// Destructor
+~SweepContext();
+
+void set_head(Point* p1);
+
+Point* head() const;
+
+void set_tail(Point* p1);
+
+Point* tail() const;
+
+size_t point_count() const;
+
+Node* LocateNode(const Point& point);
+
+void RemoveNode(Node* node);
+
+void CreateAdvancingFront();
+
+/// Try to map a node to all sides of this triangle that don't have a neighbor
+void MapTriangleToNodes(Triangle& t);
+
+void AddToMap(Triangle* triangle);
+
+Point* GetPoint(size_t index);
+
+Point* GetPoints();
+
+void RemoveFromMap(Triangle* triangle);
+
+void AddHole(const std::vector<Point*>& polyline);
+
+void AddPoint(Point* point);
+
+AdvancingFront* front() const;
+
+void MeshClean(Triangle& triangle);
+
+std::vector<Triangle*> &GetTriangles();
+std::list<Triangle*> &GetMap();
+
+std::vector<Edge*> edge_list;
+
+struct Basin {
+  Node* left_node;
+  Node* bottom_node;
+  Node* right_node;
+  double width;
+  bool left_highest;
+
+  Basin()
+  : left_node(nullptr), bottom_node(nullptr), right_node(nullptr), width(0.0), left_highest(false)
+  {
+  }
+
+  void Clear()
+  {
+    left_node = nullptr;
+    bottom_node = nullptr;
+    right_node = nullptr;
+    width = 0.0;
+    left_highest = false;
+  }
+};
+
+struct EdgeEvent {
+  Edge* constrained_edge;
+  bool right;
+
+  EdgeEvent() : constrained_edge(NULL), right(false)
+  {
+  }
+};
+
+Basin basin;
+EdgeEvent edge_event;
+
+private:
+
+friend class Sweep;
+
+std::vector<Triangle*> triangles_;
+std::list<Triangle*> map_;
+std::vector<Point*> points_;
+
+// Advancing front
+AdvancingFront* front_;
+// head point used with advancing front
+Point* head_;
+// tail point used with advancing front
+Point* tail_;
+
+Node *af_head_, *af_middle_, *af_tail_;
+
+void InitTriangulation();
+void InitEdges(const std::vector<Point*>& polyline);
+
+};
+
+inline AdvancingFront* SweepContext::front() const
+{
+  return front_;
+}
+
+inline size_t SweepContext::point_count() const
+{
+  return points_.size();
+}
+
+inline void SweepContext::set_head(Point* p1)
+{
+  head_ = p1;
+}
+
+inline Point* SweepContext::head() const
+{
+  return head_;
+}
+
+inline void SweepContext::set_tail(Point* p1)
+{
+  tail_ = p1;
+}
+
+inline Point* SweepContext::tail() const
+{
+  return tail_;
+}
+
+}