Use poly2tri for triangulation. This fixes some cases where polyPartition couldn't triangulate successfully. Reported as issue #9 in polyPartition repository. Tested with MotorHalter_0.stl cut at 1.2

xs/src/poly2tri/sweep/sweep_context.h

@@ -0,0 +1,186 @@
+/*
+ * 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(const 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(const 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(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(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(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_;
+}
+
+}
+
+#endif