Triangle::NeighborAcross to return a pointer

Same as Triangle::NeighborCW and Triangle::NeighborCCW

poly2tri/common/shapes.cc

@@ -243,6 +243,17 @@ Point* Triangle::PointCCW(const Point& point)
   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)
 {
@@ -349,23 +360,6 @@ void Triangle::SetDelunayEdgeCW(const Point& p, bool e)
   }
 }
 
-// The neighbor across to given point
-Triangle& Triangle::NeighborAcross(const Point& opoint)
-{
-  Triangle* neighbor = nullptr;
-  if (&opoint == points_[0]) {
-    neighbor = neighbors_[0];
-  } else if (&opoint == points_[1]) {
-    neighbor = neighbors_[1];
-  } else {
-    neighbor = neighbors_[2];
-  }
-  if (neighbor == nullptr) {
-      throw std::runtime_error("NeighborAcross - null neighbor");
-  }
-  return *neighbor;
-}
-
 void Triangle::DebugPrint()
 {
   std::cout << *points_[0] << " " << *points_[1] << " " << *points_[2] << std::endl;

poly2tri/common/shapes.h

@@ -176,6 +176,7 @@ 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);
@@ -203,8 +204,6 @@ void ClearDelunayEdges();
 inline bool IsInterior();
 inline void IsInterior(bool b);
 
-Triangle& NeighborAcross(const Point& opoint);
-
 void DebugPrint();
 
 bool CircumcicleContains(const Point&) const;

poly2tri/sweep/sweep.cc

@@ -108,6 +108,9 @@ void Sweep::EdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
 
 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;
   }
@@ -115,13 +118,13 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
   Point* p1 = triangle->PointCCW(point);
   Orientation o1 = Orient2d(eq, *p1, ep);
   if (o1 == COLLINEAR) {
-    if( triangle->Contains(&eq, p1)) {
+    if (triangle->Contains(&eq, p1)) {
-      triangle->MarkConstrainedEdge(&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);
+      triangle = triangle->NeighborAcross(point);
-      EdgeEvent( tcx, ep, *p1, triangle, *p1 );
+      EdgeEvent(tcx, ep, *p1, triangle, *p1);
     } else {
       throw std::runtime_error("EdgeEvent - collinear points not supported");
     }
@@ -131,13 +134,13 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
   Point* p2 = triangle->PointCW(point);
   Orientation o2 = Orient2d(eq, *p2, ep);
   if (o2 == COLLINEAR) {
-    if( triangle->Contains(&eq, p2)) {
+    if (triangle->Contains(&eq, p2)) {
-      triangle->MarkConstrainedEdge(&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);
+      triangle = triangle->NeighborAcross(point);
-      EdgeEvent( tcx, ep, *p2, triangle, *p2 );
+      EdgeEvent(tcx, ep, *p2, triangle, *p2);
     } else {
       throw std::runtime_error("EdgeEvent - collinear points not supported");
     }
@@ -149,12 +152,13 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
     // that will cross edge
     if (o1 == CW) {
       triangle = triangle->NeighborCCW(point);
-    }       else{
+    } 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);
   }
 }
@@ -215,7 +219,6 @@ void Sweep::Fill(SweepContext& tcx, Node& node)
   if (!Legalize(tcx, *triangle)) {
     tcx.MapTriangleToNodes(*triangle);
   }
-
 }
 
 void Sweep::FillAdvancingFront(SweepContext& tcx, Node& n)
@@ -293,7 +296,7 @@ double Sweep::Angle(const Point* origin, const Point* pa, const Point* pb) const
    */
   const double px = origin->x;
   const double py = origin->y;
-  const double ax = pa->x- px;
+  const double ax = pa->x - px;
   const double ay = pa->y - py;
   const double bx = pb->x - px;
   const double by = pb->y - py;
@@ -586,7 +589,7 @@ void Sweep::FillRightBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
     if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
       // Concave
       FillRightConcaveEdgeEvent(tcx, edge, node);
-    } else{
+    } else {
       // Convex
       FillRightConvexEdgeEvent(tcx, edge, node);
       // Retry this one
@@ -610,7 +613,6 @@ void Sweep::FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
       }
     }
   }
-
 }
 
 void Sweep::FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
@@ -619,13 +621,13 @@ void Sweep::FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
   if (Orient2d(*node.next->point, *node.next->next->point, *node.next->next->next->point) == CCW) {
     // Concave
     FillRightConcaveEdgeEvent(tcx, edge, *node.next);
-  } else{
+  } 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{
+    } else {
       // Above
     }
   }
@@ -664,13 +666,13 @@ void Sweep::FillLeftConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
   if (Orient2d(*node.prev->point, *node.prev->prev->point, *node.prev->prev->prev->point) == CW) {
     // Concave
     FillLeftConcaveEdgeEvent(tcx, edge, *node.prev);
-  } else{
+  } 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{
+    } else {
       // Above
     }
   }
@@ -686,17 +688,22 @@ void Sweep::FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
       if (Orient2d(*node.point, *node.prev->point, *node.prev->prev->point) == CW) {
         // Next is concave
         FillLeftConcaveEdgeEvent(tcx, edge, node);
-      } else{
+      } else {
         // Next is convex
       }
     }
   }
-
 }
 
 void Sweep::FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p)
 {
-  Triangle& ot = t->NeighborAcross(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)) {
@@ -762,7 +769,11 @@ Point& Sweep::NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op)
 void Sweep::FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle,
                               Triangle& t, Point& p)
 {
-  Triangle& ot = t.NeighborAcross(p);
+  Triangle* ot_ptr = t.NeighborAcross(p);
+  if (ot_ptr == nullptr) {
+    throw std::runtime_error("FlipScanEdgeEvent - null neighbor across");
+  }
+  Triangle& ot = *ot_ptr;
   Point& op = *ot.OppositePoint(t, p);
 
   if (InScanArea(eq, *flip_triangle.PointCCW(eq), *flip_triangle.PointCW(eq), op)) {
@@ -775,7 +786,7 @@ void Sweep::FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle&
     // 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{
+  } else {
     Point& newP = NextFlipPoint(ep, eq, ot, op);
     FlipScanEdgeEvent(tcx, ep, eq, flip_triangle, ot, newP);
   }
@@ -790,5 +801,4 @@ Sweep::~Sweep() {
 
 }
 
-}
+} // namespace p2t
-

unittest/main.cpp

@@ -21,7 +21,7 @@ BOOST_AUTO_TEST_CASE(BasicTest)
     new p2t::Point(1, 1),
   };
   p2t::CDT cdt{ polyline };
-  cdt.Triangulate();
+  BOOST_CHECK_NO_THROW(cdt.Triangulate());
   const auto result = cdt.GetTriangles();
   BOOST_REQUIRE_EQUAL(result.size(), 1);
   BOOST_CHECK_EQUAL(*result[0]->GetPoint(0), *polyline[0]);
@@ -38,7 +38,7 @@ BOOST_AUTO_TEST_CASE(QuadTest)
   std::vector<p2t::Point*> polyline{ new p2t::Point(0, 0), new p2t::Point(0, 1),
                                      new p2t::Point(1, 1), new p2t::Point(1, 0) };
   p2t::CDT cdt{ polyline };
-  cdt.Triangulate();
+  BOOST_CHECK_NO_THROW(cdt.Triangulate());
   const auto result = cdt.GetTriangles();
   BOOST_REQUIRE_EQUAL(result.size(), 2);
   BOOST_CHECK(p2t::IsDelaunay(result));
@@ -47,7 +47,7 @@ BOOST_AUTO_TEST_CASE(QuadTest)
   }
 }
 
-BOOST_AUTO_TEST_CASE(QuadTestThrow)
+BOOST_AUTO_TEST_CASE(NarrowQuadTest)
 {
   // Very narrow quad that demonstrates a failure case during triangulation
   std::vector<p2t::Point*> polyline {
@@ -92,7 +92,7 @@ BOOST_AUTO_TEST_CASE(TestbedFilesTest)
       polyline.push_back(new p2t::Point(x, y));
     }
     p2t::CDT cdt{ polyline };
-    cdt.Triangulate();
+    BOOST_CHECK_NO_THROW(cdt.Triangulate());
     const auto result = cdt.GetTriangles();
     BOOST_REQUIRE(result.size() * 3 > polyline.size());
     BOOST_CHECK_MESSAGE(p2t::IsDelaunay(result), filename + std::to_string(polyline.size()));