polygon: added poly2tri library.

Requied for constrained Delaunay triangulation (P&S/ratsnest) and zone tesselation (GAL).

polygon/CMakeLists.txt

@@ -9,6 +9,12 @@ set(POLYGON_SRCS
     PolyLine.cpp
     polygon_test_point_inside.cpp
     clipper.cpp
-    )
+    
+    poly2tri/common/shapes.cc
+    poly2tri/sweep/sweep.cc
+    poly2tri/sweep/cdt.cc
+    poly2tri/sweep/advancing_front.cc
+    poly2tri/sweep/sweep_context.cc
+)
 
 add_library(polygon STATIC ${POLYGON_SRCS})

polygon/poly2tri/common/shapes.cc

+/* 
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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 <iostream>
+
+namespace p2t {
+
+Triangle::Triangle(Point& a, Point& b, Point& c)
+{
+  points_[0] = &a; points_[1] = &b; points_[2] = &c;
+  neighbors_[0] = NULL; neighbors_[1] = NULL; neighbors_[2] = NULL;
+  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( int i=0; i<3; i++ )
+    {
+        t = neighbors_[i];
+        if( t != NULL )
+        {
+            t->ClearNeighbor( this );
+        }
+    }
+    ClearNeighbors();
+    points_[0]=points_[1]=points_[2] = NULL;
+}
+
+void Triangle::ClearNeighbor(Triangle *triangle )
+{
+    if( neighbors_[0] == triangle )
+    {
+        neighbors_[0] = NULL;
+    }
+    else if( neighbors_[1] == triangle )
+    {
+        neighbors_[1] = NULL;            
+    }
+    else
+    {
+        neighbors_[2] = NULL;
+    }
+}
+    
+void Triangle::ClearNeighbors()
+{
+  neighbors_[0] = NULL;
+  neighbors_[1] = NULL;
+  neighbors_[2] = NULL;
+}
+
+void Triangle::ClearDelunayEdges()
+{
+  delaunay_edge[0] = delaunay_edge[1] = delaunay_edge[2] = false;
+}
+
+Point* Triangle::OppositePoint(Triangle& t, Point& p)
+{
+  Point *cw = t.PointCW(p);
+  double x = cw->x;
+  double y = cw->y;
+  x = p.x;
+  y = p.y;
+  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);
+}
+
+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(const 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(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);
+}
+
+// The point counter-clockwise to given point
+Point* Triangle::PointCCW(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);
+}
+
+// The neighbor clockwise to given point
+Triangle* Triangle::NeighborCW(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(Point& point)
+{
+  if (&point == points_[0]) {
+    return neighbors_[2];
+  } else if (&point == points_[1]) {
+    return neighbors_[0];
+  }
+  return neighbors_[1];
+}
+
+bool Triangle::GetConstrainedEdgeCCW(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(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(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(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(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(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(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(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;
+  }
+}
+
+// The neighbor across to given point
+Triangle& Triangle::NeighborAcross(Point& opoint)
+{
+  if (&opoint == points_[0]) {
+    return *neighbors_[0];
+  } else if (&opoint == points_[1]) {
+    return *neighbors_[1];
+  }
+  return *neighbors_[2];
+}
+
+void Triangle::DebugPrint()
+{
+  using namespace std;
+  cout << points_[0]->x << "," << points_[0]->y << " ";
+  cout << points_[1]->x << "," << points_[1]->y << " ";
+  cout << points_[2]->x << "," << points_[2]->y << endl;
+}
+
+}
+

polygon/poly2tri/common/shapes.h

+/*
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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 guard
+#ifndef SHAPES_H
+#define SHAPES_H
+
+#include <vector>
+#include <cstddef>
+#include <assert.h>
+#include <cmath>
+
+namespace p2t {
+
+struct Edge;
+
+struct 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) : x(x), y(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()
+  {
+    double len = Length();
+    x /= len;
+    y /= len;
+    return len;
+  }
+
+};
+
+// Represents a simple polygon's edge
+struct 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
+        assert(false);
+      }
+    }
+
+    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 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(const int& index);
+Point* PointCW(Point& point);
+Point* PointCCW(Point& point);
+Point* OppositePoint(Triangle& t, Point& p);
+
+Triangle* GetNeighbor(const int& index);
+void MarkNeighbor(Point* p1, Point* p2, Triangle* t);
+void MarkNeighbor(Triangle& t);
+
+void MarkConstrainedEdge(const 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* NeighborCW(Point& point);
+Triangle* NeighborCCW(Point& point);
+bool GetConstrainedEdgeCCW(Point& p);
+bool GetConstrainedEdgeCW(Point& p);
+void SetConstrainedEdgeCCW(Point& p, bool ce);
+void SetConstrainedEdgeCW(Point& p, bool ce);
+bool GetDelunayEdgeCCW(Point& p);
+bool GetDelunayEdgeCW(Point& p);
+void SetDelunayEdgeCCW(Point& p, bool e);
+void SetDelunayEdgeCW(Point& p, bool e);
+
+bool Contains(Point* p);
+bool Contains(const Edge& e);
+bool Contains(Point* p, 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(Triangle *triangle );
+void ClearNeighbors();
+void ClearDelunayEdges();
+
+inline bool IsInterior();
+inline void IsInterior(bool b);
+
+Triangle& NeighborAcross(Point& opoint);
+
+void DebugPrint();
+
+private:
+
+/// 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(const double s, const Point& a)
+{
+  return Point(-s * a.y, s * a.x);
+}
+
+inline Point* Triangle::GetPoint(const int& index)
+{
+  return points_[index];
+}
+
+inline Triangle* Triangle::GetNeighbor(const int& index)
+{
+  return neighbors_[index];
+}
+
+inline bool Triangle::Contains(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(Point* p, Point* q)
+{
+  return Contains(p) && Contains(q);
+}
+
+inline bool Triangle::IsInterior()
+{
+  return interior_;
+}
+
+inline void Triangle::IsInterior(bool b)
+{
+  interior_ = b;
+}
+
+}
+
+#endif
+
+

polygon/poly2tri/common/utils.h

+/* 
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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.
+ */
+ 
+#ifndef UTILS_H
+#define UTILS_H
+
+// Otherwise #defines like M_PI are undeclared under Visual Studio
+#define _USE_MATH_DEFINES
+
+#include <exception>
+#include <math.h>
+
+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(Point& pa, Point& pb, 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;
+  if (val > -EPSILON && val < EPSILON) {
+    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(Point& pa, Point& pb, Point& pc, 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;
+}
+
+}
+
+#endif
+

polygon/poly2tri/poly2tri.h

+/* 
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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.
+ */
+
+#ifndef POLY2TRI_H
+#define POLY2TRI_H
+
+#include "common/shapes.h"
+#include "sweep/cdt.h"
+
+#endif
+

polygon/poly2tri/sweep/advancing_front.cc

+/*
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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"
+
+namespace p2t {
+
+AdvancingFront::AdvancingFront(Node& head, Node& tail)
+{
+  head_ = &head;
+  tail_ = &tail;
+  search_node_ = &head;
+}
+
+Node* AdvancingFront::LocateNode(const double& x)
+{
+  Node* node = search_node_;
+
+  if (x < node->value) {
+    while ((node = node->prev) != NULL) {
+      if (x >= node->value) {
+        search_node_ = node;
+        return node;
+      }
+    }
+  } else {
+    while ((node = node->next) != NULL) {
+      if (x < node->value) {
+        search_node_ = node->prev;
+        return node->prev;
+      }
+    }
+  }
+  return NULL;
+}
+
+Node* AdvancingFront::FindSearchNode(const 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) != NULL) {
+      if (point == node->point) {
+        break;
+      }
+    }
+  } else {
+    while ((node = node->next) != NULL) {
+      if (point == node->point)
+        break;
+    }
+  }
+  if(node) search_node_ = node;
+  return node;
+}
+
+AdvancingFront::~AdvancingFront()
+{
+}
+
+}
+

polygon/poly2tri/sweep/advancing_front.h

+/*
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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.
+ */
+
+#ifndef ADVANCED_FRONT_H
+#define ADVANCED_FRONT_H
+
+#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(const double& x);
+
+Node* LocatePoint(const Point* point);
+
+private:
+
+Node* head_, *tail_, *search_node_;
+
+Node* FindSearchNode(const 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;
+}
+
+}
+
+#endif

polygon/poly2tri/sweep/cdt.cc

+/* 
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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(std::vector<Point*> polyline)
+{
+  sweep_context_ = new SweepContext(polyline);
+  sweep_ = new Sweep;
+}
+
+void CDT::AddHole(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_;
+}
+
+}
+

polygon/poly2tri/sweep/cdt.h

+/* 
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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.
+ */
+ 
+#ifndef CDT_H
+#define CDT_H
+
+#include "advancing_front.h"
+#include "sweep_context.h"
+#include "sweep.h"
+
+/**
+ * 
+ * @author Mason Green <mason.green@gmail.com>
+ *
+ */
+ 
+namespace p2t {
+
+class CDT
+{
+public:
+
+  /**
+   * Constructor - add polyline with non repeating points
+   * 
+   * @param polyline
+   */
+  CDT(std::vector<Point*> polyline);
+  
+   /**
+   * Destructor - clean up memory
+   */
+  ~CDT();
+  
+  /**
+   * Add a hole
+   * 
+   * @param polyline
+   */
+  void AddHole(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_;
+
+};
+
+}
+
+#endif

polygon/poly2tri/sweep/sweep.h

+/*
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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 hln, thahlen@gmail.com
+ */
+
+#ifndef SWEEP_H
+#define SWEEP_H
+
+#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(Point& pa, Point& pb, Point& pc, Point& pd);
+
+  /**
+   * 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);
+
+  /**
+   * 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(Node* node);
+  bool AngleExceeds90Degrees(Point* origin, Point* pa, Point* pb);
+  bool AngleExceedsPlus90DegreesOrIsNegative(Point* origin, Point* pa, Point* pb);
+  double Angle(Point& origin, Point& pa, Point& pb);
+
+  /**
+   *
+   * @param node - middle node
+   * @return the angle between 3 front nodes
+   */
+  double HoleAngle(Node& node);
+
+  /**
+   * The basin angle is decided against the horizontal line [1,0]
+   */
+  double BasinAngle(Node& node);
+
+  /**
+   * 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_;
+
+};
+
+}
+
+#endif

polygon/poly2tri/sweep/sweep_context.cc

+/*
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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) :
+  front_(0),
+  head_(0),
+  tail_(0),
+  af_head_(0),
+  af_middle_(0),
+  af_tail_(0)
+{
+  basin = Basin();
+  edge_event = EdgeEvent();
+
+  points_ = polyline;
+
+  InitEdges(points_);
+}
+
+void SweepContext::AddHole(std::vector<Point*> polyline)
+{
+  InitEdges(polyline);
+  for(unsigned int i = 0; i < polyline.size(); i++) {
+    points_.push_back(polyline[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 (unsigned int i = 0; i < points_.size(); i++) {
+    Point& p = *points_[i];
+    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(xmax + dx, ymin - dy);
+  tail_ = new Point(xmin - dx, ymin - dy);
+
+  // Sort points along y-axis
+  std::sort(points_.begin(), points_.end(), cmp);
+
+}
+
+void SweepContext::InitEdges(std::vector<Point*> polyline)
+{
+  int num_points = polyline.size();
+  for (int i = 0; i < num_points; i++) {
+    int j = i < num_points - 1 ? i + 1 : 0;
+    edge_list.push_back(new Edge(*polyline[i], *polyline[j]));
+  }
+}
+
+Point* SweepContext::GetPoint(const int& index)
+{
+  return points_[index];
+}
+
+void SweepContext::AddToMap(Triangle* triangle)
+{
+  map_.push_back(triangle);
+}
+
+Node& SweepContext::LocateNode(Point& point)
+{
+  // TODO implement search tree
+  return *front_->LocateNode(point.x);
+}
+
+void SweepContext::CreateAdvancingFront(std::vector<Node*> nodes)
+{
+
+  (void) nodes;
+  // Initial triangle
+  Triangle* triangle = new Triangle(*points_[0], *tail_, *head_);
+
+  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 != NULL && !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_;
+
+    typedef std::list<Triangle*> type_list;
+
+    for(type_list::iterator iter = map_.begin(); iter != map_.end(); ++iter) {
+        Triangle* ptr = *iter;
+        delete ptr;
+    }
+
+     for(unsigned int i = 0; i < edge_list.size(); i++) {
+        delete edge_list[i];
+    }
+
+}
+
+}

polygon/poly2tri/sweep/sweep_context.h

+/*
+ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
+ * http://code.google.com/p/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.
+ */
+
+#ifndef SWEEP_CONTEXT_H
+#define SWEEP_CONTEXT_H
+
+#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
+SweepContext(std::vector<Point*> polyline);
+/// Destructor
+~SweepContext();
+
+void set_head(Point* p1);
+
+Point* head();
+
+void set_tail(Point* p1);
+
+Point* tail();
+
+int point_count();
+
+Node& LocateNode(Point& point);
+
+void RemoveNode(Node* node);
+
+void CreateAdvancingFront(std::vector<Node*> nodes);
+
+/// 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(const int& index);
+
+Point* GetPoints();
+
+void RemoveFromMap(Triangle* triangle);
+
+void AddHole(std::vector<Point*> polyline);
+
+void AddPoint(Point* point);
+
+AdvancingFront* front();
+
+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(NULL), bottom_node(NULL), right_node(NULL), width(0.0), left_highest(false)
+  {
+  }
+
+  void Clear()
+  {
+    left_node = NULL;
+    bottom_node = NULL;
+    right_node = NULL;
+    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(std::vector<Point*> polyline);
+
+};
+
+inline AdvancingFront* SweepContext::front()
+{
+  return front_;
+}
+
+inline int SweepContext::point_count()
+{
+  return points_.size();
+}
+
+inline void SweepContext::set_head(Point* p1)
+{
+  head_ = p1;
+}
+
+inline Point* SweepContext::head()
+{
+  return head_;
+}
+
+inline void SweepContext::set_tail(Point* p1)
+{
+  tail_ = p1;
+}
+
+inline Point* SweepContext::tail()
+{
+  return tail_;
+}
+
+}
+
+#endif