Thread-safe version of Delaunay triangulation.

common/geometry/hetriang.cpp

@@ -51,8 +51,6 @@ using namespace hed;
 using namespace std;
 
 
-Triangulation* TTLtraits::triang_ = NULL;
-
 #ifdef TTL_USE_NODE_ID
   int Node::id_count = 0;
 #endif
@@ -164,11 +162,30 @@ EdgePtr Triangulation::initTwoEnclosingTriangles(NodesContainer::iterator first,
 }
 
 
+//--------------------------------------------------------------------------------------------------
+Triangulation::Triangulation() {
+  helper = new ttl::TriangulationHelper( *this );
+}
+
+
+//--------------------------------------------------------------------------------------------------
+Triangulation::Triangulation(const Triangulation& tr) {
+  std::cout << "Triangulation: Copy constructor not present - EXIT.";
+  exit(-1);
+}
+
+
+//--------------------------------------------------------------------------------------------------
+Triangulation::~Triangulation() {
+  cleanAll();
+  delete helper;
+}
+
+
 //--------------------------------------------------------------------------------------------------
 void Triangulation::createDelaunay(NodesContainer::iterator first,
                                    NodesContainer::iterator last) {
 
-  TTLtraits::triang_ = this;
   cleanAll();
   
   EdgePtr bedge = initTwoEnclosingTriangles(first, last);
@@ -178,7 +195,7 @@ void Triangulation::createDelaunay(NodesContainer::iterator first,
   
   NodesContainer::iterator it;
   for (it = first; it != last; ++it) {
-      ttl::insertNode<TTLtraits>(d_iter, *it);
+      helper->insertNode<TTLtraits>(d_iter, *it);
   }
 
   // In general (e.g. for the triangle based data structure), the initial dart
@@ -189,7 +206,7 @@ void Triangulation::createDelaunay(NodesContainer::iterator first,
   // triangle "outside" the triangulation.)
 
   // Assumes rectangular domain
-  ttl::removeRectangularBoundary<TTLtraits>(dc);
+  helper->removeRectangularBoundary<TTLtraits>(dc);
 }
 
 
@@ -269,7 +286,7 @@ cout << "Iterate boundary 2" << endl;
 
   Dart dart_iter = dart;
   do {
-  if (ttl::isBoundaryEdge(dart_iter))
+  if (helper->isBoundaryEdge(dart_iter))
   dart_iter.alpha0().alpha1();
   else
   dart_iter.alpha2().alpha1();
@@ -322,6 +339,31 @@ void Triangulation::cleanAll() {
 }
 
 
+//--------------------------------------------------------------------------------------------------
+void Triangulation::swapEdge(Dart& dart) {
+  if (!dart.getEdge()->isConstrained()) swapEdge(dart.getEdge());
+}
+
+
+//--------------------------------------------------------------------------------------------------
+void Triangulation::splitTriangle(Dart& dart, NodePtr point) {
+  EdgePtr edge = splitTriangle(dart.getEdge(), point);
+  dart.init(edge);
+}
+
+
+//--------------------------------------------------------------------------------------------------
+void Triangulation::reverse_splitTriangle(Dart& dart) {
+  reverse_splitTriangle(dart.getEdge());
+}
+
+
+//--------------------------------------------------------------------------------------------------
+void Triangulation::removeBoundaryTriangle(Dart& d) {
+  removeTriangle(d.getEdge());
+}
+
+
 #ifdef TTL_USE_NODE_FLAG
 //--------------------------------------------------------------------------------------------------
 // This is a "template" for accessing all nodes (but multiple tests)
@@ -486,7 +528,7 @@ void Triangulation::swapEdge(EdgePtr& diagonal) {
   
   // Note that diagonal is both input and output and it is always
   // kept in counterclockwise direction (this is not required by all 
-  // finctions in ttl:: now)
+  // functions in TriangulationHelper now)
   
   // Swap by rotating counterclockwise
   // Use the same objects - no deletion or new objects
@@ -567,7 +609,7 @@ bool Triangulation::checkDelaunay() const {
       // only one of the half-edges
       if (!twinedge || (size_t)edge.get() > (size_t)twinedge.get()) {
         Dart dart(edge);
-        if (ttl::swapTestDelaunay<TTLtraits>(dart)) {
+        if (helper->swapTestDelaunay<TTLtraits>(dart)) {
           noNotDelaunay++;
           
           //printEdge(dart,os); os << "\n";
@@ -610,7 +652,7 @@ void Triangulation::optimizeDelaunay() {
       
       Dart dart(edge);
       // Constrained edges should not be swapped
-      if (!edge->isConstrained() && ttl::swapTestDelaunay<TTLtraits>(dart, cycling_check)) {
+      if (!edge->isConstrained() && helper->swapTestDelaunay<TTLtraits>(dart, cycling_check)) {
         optimal = false;
         swapEdge(edge);
       }
@@ -632,7 +674,7 @@ EdgePtr Triangulation::getInteriorNode() const {
     for (int i = 0; i < 3; ++i) {
       if (edge->getTwinEdge()) {
         
-        if (!ttl::isBoundaryNode(Dart(edge)))
+        if (!helper->isBoundaryNode(Dart(edge)))
           return edge;
       }
       edge = edge->getNextEdgeInFace();
@@ -643,18 +685,18 @@ EdgePtr Triangulation::getInteriorNode() const {
 
 
 //--------------------------------------------------------------------------------------------------
-static EdgePtr getBoundaryEdgeInTriangle(const EdgePtr& e) {
+EdgePtr Triangulation::getBoundaryEdgeInTriangle(const EdgePtr& e) const {
   EdgePtr edge = e;
   
-  if (ttl::isBoundaryEdge(Dart(edge)))
+  if (helper->isBoundaryEdge(Dart(edge)))
     return edge;
 
   edge = edge->getNextEdgeInFace();
-  if (ttl::isBoundaryEdge(Dart(edge)))
+  if (helper->isBoundaryEdge(Dart(edge)))
     return edge;
 
   edge = edge->getNextEdgeInFace();
-  if (ttl::isBoundaryEdge(Dart(edge)))
+  if (helper->isBoundaryEdge(Dart(edge)))
     return edge;
   
   return EdgePtr();

include/ttl/halfedge/hetraits.h

@@ -69,9 +69,6 @@ namespace hed {
 
   struct TTLtraits {
     
-    // The actual triangulation object
-    static Triangulation* triang_;
-    
     /** The floating point type used in calculations
     *   involving scalar products and cross products.
     */
@@ -172,127 +169,6 @@ namespace hed {
     }
 
     //@} // End of Geometric Predicates Group
-
-
-    // A rationale for directing these functions to traits is:
-    // e.g., constraints
-
-    //----------------------------------------------------------------------------------------------
-    /* Checks if the edge associated with \e dart should be swapped
-    *   according to the Delaunay criterion.<br>
-    *
-    *   \note
-    *   This function is also present in the TTL as ttl::swapTestDelaunay.<br>
-    *   Thus, the function can be implemented simply as:
-    *   \code
-    *   { return ttl::swapTestDelaunay<TTLtraits>(dart); }
-    *   \endcode
-    */
-    //static bool swapTestDelaunay(const Dart& dart) {
-    //  return ttl::swapTestDelaunay<TTLtraits>(dart);
-    //}
-
-
-    //----------------------------------------------------------------------------------------------
-    /* Checks if the edge associated with \e dart can be swapped, i.e.,
-    *   if the edge is a diagonal in a (strictly) convex quadrilateral.
-    *   This function is also present as ttl::swappableEdge.
-    */
-    //static bool swappableEdge(const Dart& dart) {
-    //  return ttl::swappableEdge<TTLtraits>(dart);
-    //}
-
-
-    //----------------------------------------------------------------------------------------------
-    /* Checks if the edge associated with \e dart should be \e fixed, meaning
-    *   that it should never be swapped. ??? Use when constraints.
-    */
-    //static bool fixedEdge(const Dart& dart) {
-    //  return dart.getEdge()->isConstrained();
-    //}
-
-
-    //----------------------------------------------------------------------------------------------
-    // ----------------------- Functions for Delaunay Triangulation Group -------------------------
-    //----------------------------------------------------------------------------------------------
-
-    /** @name Functions for Delaunay Triangulation */
-    //@{
-
-    //----------------------------------------------------------------------------------------------
-    /** Swaps the edge associated with \e dart in the actual data structure.
-    *
-    *   <center>
-    *   \image html swapEdge.gif
-    *   </center>
-    * 
-    *   \param dart
-    *   Some of the functions require a dart as output.
-    *   If this is required by the actual function, the dart should be delivered
-    *   back in a position as seen if it was glued to the edge when swapping (rotating)
-    *   the edge CCW; see the figure.
-    *
-    *   \note
-    *   - If the edge is \e constrained, or if it should not be swapped for
-    *     some other reason, this function need not do the actual swap of the edge.
-    *   - Some functions in TTL require that \c swapEdge is implemented such that
-    *     darts outside the quadrilateral are not affected by the swap.
-    */
-    static void swapEdge(Dart& dart) {
-      if (!dart.getEdge()->isConstrained()) triang_->swapEdge(dart.getEdge());
-    }
-
-
-    //----------------------------------------------------------------------------------------------
-    /** Splits the triangle associated with \e dart in the actual data structure into
-    *   three new triangles joining at \e point.
-    *
-    *   <center>
-    *   \image html splitTriangle.gif
-    *   </center>
-    *
-    *   \param dart
-    *   Output: A CCW dart incident with the new node; see the figure.
-    */
-    static void splitTriangle(Dart& dart, NodePtr point) {
-      EdgePtr edge = triang_->splitTriangle(dart.getEdge(), point);
-      dart.init(edge);
-    }
-    
-    //@} // End of Functions for Delaunay Triangulation group
-
-
-    //----------------------------------------------------------------------------------------------
-    // --------------------------- Functions for removing nodes Group -----------------------------
-    //----------------------------------------------------------------------------------------------
-
-    /** @name Functions for removing nodes */
-    //@{
-
-    //----------------------------------------------------------------------------------------------
-    /** The reverse operation of TTLtraits::splitTriangle.
-    *   This function is only required for functions that involve
-    *   removal of interior nodes; see for example ttl::removeInteriorNode.
-    *
-    *   <center>
-    *   \image html reverse_splitTriangle.gif
-    *   </center>
-    */
-    static void reverse_splitTriangle(Dart& dart) {
-      triang_->reverse_splitTriangle(dart.getEdge());
-    }
-
-
-    //----------------------------------------------------------------------------------------------
-    /** Removes a triangle with an edge at the boundary of the triangulation
-    *   in the actual data structure
-    */
-    static void removeBoundaryTriangle(Dart& d) {
-      triang_->removeTriangle(d.getEdge());
-    }
-
-    //@} // End of Functions for removing nodes Group
-
   };
 
 }; // End of hed namespace

include/ttl/halfedge/hetriang.h

@@ -51,10 +51,13 @@
 #include <vector>
 #include <iostream>
 #include <fstream>
-#include <ttl/ttl.h>
 #include <ttl/ttl_util.h>
 #include <boost/shared_ptr.hpp>
 
+namespace ttl {
+  class TriangulationHelper;
+};
+
 //--------------------------------------------------------------------------------------------------
 // The half-edge data structure
 //--------------------------------------------------------------------------------------------------
@@ -242,26 +245,75 @@ public:
   class Triangulation {
 
   protected:
-    list<EdgePtr> leadingEdges_; // one half-edge for each arc
+    std::list<EdgePtr> leadingEdges_; // one half-edge for each arc
+
+    ttl::TriangulationHelper* helper;
+
     void addLeadingEdge(EdgePtr& edge) {
         edge->setAsLeadingEdge();
         leadingEdges_.push_front( edge );
     }
+
     bool removeLeadingEdgeFromList(EdgePtr& leadingEdge);
+
     void cleanAll();
     
+    /** Swaps the edge associated with \e dart in the actual data structure.
+    *
+    *   <center>
+    *   \image html swapEdge.gif
+    *   </center>
+    *
+    *   \param dart
+    *   Some of the functions require a dart as output.
+    *   If this is required by the actual function, the dart should be delivered
+    *   back in a position as seen if it was glued to the edge when swapping (rotating)
+    *   the edge CCW; see the figure.
+    *
+    *   \note
+    *   - If the edge is \e constrained, or if it should not be swapped for
+    *     some other reason, this function need not do the actual swap of the edge.
+    *   - Some functions in TTL require that \c swapEdge is implemented such that
+    *     darts outside the quadrilateral are not affected by the swap.
+    */
+    void swapEdge(Dart& dart);
+
+    /** Splits the triangle associated with \e dart in the actual data structure into
+    *   three new triangles joining at \e point.
+    *
+    *   <center>
+    *   \image html splitTriangle.gif
+    *   </center>
+    *
+    *   \param dart
+    *   Output: A CCW dart incident with the new node; see the figure.
+    */
+    void splitTriangle(Dart& dart, NodePtr point);
+
+    /** The reverse operation of TTLtraits::splitTriangle.
+    *   This function is only required for functions that involve
+    *   removal of interior nodes; see for example TrinagulationHelper::removeInteriorNode.
+    *
+    *   <center>
+    *   \image html reverse_splitTriangle.gif
+    *   </center>
+    */
+    void reverse_splitTriangle(Dart& dart);
+
+    /** Removes a triangle with an edge at the boundary of the triangulation
+    *   in the actual data structure
+    */
+    void removeBoundaryTriangle(Dart& d);
+
   public:
     /// Default constructor
-    Triangulation() {}
+    Triangulation();
     
     /// Copy constructor
-    Triangulation(const Triangulation& tr) { 
-	std::cout << "Triangulation: Copy constructor not present - EXIT."; 
-      exit(-1);
-    }
+    Triangulation(const Triangulation& tr);
 
     /// Destructor
-    ~Triangulation() { cleanAll(); }
+    ~Triangulation();
     
     /// Creates a Delaunay triangulation from a set of points
     void createDelaunay(NodesContainer::iterator first,
@@ -295,20 +347,20 @@ public:
     Dart createDart();
 
     /// Returns a list of "triangles" (one leading half-edge for each triangle)
-    const list<EdgePtr>& getLeadingEdges() const { return leadingEdges_; }
+    const std::list<EdgePtr>& getLeadingEdges() const { return leadingEdges_; }
 
     /// Returns the number of triangles
       int noTriangles() const { return (int)leadingEdges_.size(); }
     
     /// Returns a list of half-edges (one half-edge for each arc)
-    list<EdgePtr>* getEdges(bool skip_boundary_edges = false) const;
+    std::list<EdgePtr>* getEdges(bool skip_boundary_edges = false) const;
 
 #ifdef TTL_USE_NODE_FLAG
     /// Sets flag in all the nodes  
     void flagNodes(bool flag) const;
 
     /// Returns a list of nodes. This function requires TTL_USE_NODE_FLAG to be defined. \see Node.
-    list<NodePtr>* getNodes() const;
+    std::list<NodePtr>* getNodes() const;
 #endif
 
     /// Swaps edges until the triangulation is Delaunay (constrained edges are not swapped)
@@ -320,12 +372,16 @@ public:
     /// Returns an arbitrary interior node (as the source node of the returned edge)
     EdgePtr getInteriorNode() const;
 
+    EdgePtr getBoundaryEdgeInTriangle(const EdgePtr& e) const;
+
     /// Returns an arbitrary boundary edge
     EdgePtr getBoundaryEdge() const;
 
     /// Print edges for plotting with, e.g., gnuplot
     void printEdges(std::ofstream& os) const;
 
+    friend class ttl::TriangulationHelper;
+
   }; // End of class Triangulation
 
 

include/ttl/ttl_constr.h

@@ -51,9 +51,6 @@
   static ofstream ofile_constr("qweCons.dat");
 #endif
 
-
-//using namespace std;
-
 /** \brief Constrained Delaunay triangulation
 *
 *   Basic generic algorithms in TTL for inserting a constrained edge between two existing nodes.\n
@@ -61,7 +58,7 @@
 *   See documentation for the namespace ttl for general requirements and assumptions.
 *
 *   \author 
-*   Øyvind Hjelle, oyvindhj@ifi.uio.no
+*   �yvind Hjelle, oyvindhj@ifi.uio.no
 */
 
 namespace ttl_constr {
@@ -73,6 +70,9 @@ namespace ttl_constr {
 #endif
 
 
+class ConstrainedTriangulation
+{
+  public:
   //------------------------------------------------------------------------------------------------
   /* Checks if \e dart has start and end points in \e dstart and \e dend.
   *
@@ -89,14 +89,14 @@ namespace ttl_constr {
   *   A bool confirming that it's the constraint or not 
   *
   *   \using
-  *   ttl::same_0_orbit
+  *   same_0_orbit
   */
   template <class DartType>
-    bool isTheConstraint(const DartType& dart, const DartType& dstart, const DartType& dend) {
+    static bool isTheConstraint(const DartType& dart, const DartType& dstart, const DartType& dend) {
     DartType d0 = dart;
     d0.alpha0(); // CW
-    if ((ttl::same_0_orbit(dstart, dart) && ttl::same_0_orbit(dend, d0)) ||
-      (ttl::same_0_orbit(dstart, d0)  && ttl::same_0_orbit(dend, dart))) {
+    if ((ttl::TriangulationHelper::same_0_orbit(dstart, dart) && ttl::TriangulationHelper::same_0_orbit(dend, d0)) ||
+      (ttl::TriangulationHelper::same_0_orbit(dstart, d0) && ttl::TriangulationHelper::same_0_orbit(dend, dart))) {
       return true;
     }
     return false;
@@ -123,7 +123,7 @@ namespace ttl_constr {
   *   TraitsType::orient2d
   */
   template <class TraitsType, class DartType>
-    bool crossesConstraint(DartType& dstart, DartType& dend, DartType& d1, DartType& d2) {
+    static bool crossesConstraint(DartType& dstart, DartType& dend, DartType& d1, DartType& d2) {
     
     typename TraitsType::real_type orient_1 = TraitsType::orient2d(dstart,d1,dend);
     typename TraitsType::real_type orient_2 = TraitsType::orient2d(dstart,d2,dend);
@@ -156,12 +156,12 @@ namespace ttl_constr {
   *   The dart \e d making the smallest positive (or == 0) angle
   *
   *   \using
-  *   ttl::isBoundaryNode
-  *   ttl::positionAtNextBoundaryEdge
+  *   isBoundaryNode
+  *   positionAtNextBoundaryEdge
   *   TraitsType::orient2d
   */
   template <class TraitsType, class DartType>
-    DartType getAtSmallestAngle(const DartType& dstart, const DartType& dend) {
+    static DartType getAtSmallestAngle(const DartType& dstart, const DartType& dend) {
     
     // - Must boundary be convex???
     // - Handle the case where the constraint is already present???
@@ -169,9 +169,9 @@ namespace ttl_constr {
     //   (dstart and dend may define a boundary edge)
     
     DartType d_iter = dstart;
-    if (ttl::isBoundaryNode(d_iter)) {
+    if (ttl::TriangulationHelper::isBoundaryNode(d_iter)) {
       d_iter.alpha1(); // CW
-      ttl::positionAtNextBoundaryEdge(d_iter); // CCW (was rotated CW to the boundary)
+      ttl::TriangulationHelper::positionAtNextBoundaryEdge(d_iter); // CCW (was rotated CW to the boundary)
     }
     
     // assume convex boundary; see comments
@@ -273,7 +273,7 @@ namespace ttl_constr {
   *   Returns the next "collinear" starting node such that dend is returned when done.
   */
   template <class TraitsType, class DartType, class ListType>
-    DartType findCrossingEdges(const DartType& dstart, const DartType& dend, ListType& elist) {
+    static DartType findCrossingEdges(const DartType& dstart, const DartType& dend, ListType& elist) {
     
     const DartType my_start = getAtSmallestAngle<TraitsType>(dstart, dend);
     DartType my_end   = getAtSmallestAngle<TraitsType>(dend, dstart);
@@ -387,15 +387,16 @@ namespace ttl_constr {
   *   A list containing all the edges crossing the spesified constraint
   *
   *   \using
-  *   ttl::swappableEdge
-  *   ttl::swapEdgeInList
-  *   ttl::crossesConstraint
-  *   ttl::isTheConstraint
+  *   swappableEdge
+  *   swapEdgeInList
+  *   crossesConstraint
+  *   isTheConstraint
   */
   template <class TraitsType, class DartType>
-    void transformToConstraint(DartType& dstart, DartType& dend, std::list<DartType>& elist) {
+    void transformToConstraint(ttl::TriangulationHelper helper, DartType& dstart, DartType& dend,
+                               std::list<DartType>& elist) const {
     
-    typename list<DartType>::iterator it, used;
+    typename std::list<DartType>::iterator it, used;
     
     // We may enter in a situation where dstart and dend are altered because of a swap.
     // (The general rule is that darts inside the actual quadrilateral can be changed,
@@ -423,7 +424,7 @@ namespace ttl_constr {
         if (counter > dartsInList)
           break;
         
-        if (ttl::swappableEdge<TraitsType, DartType>(*it, true)) {
+        if (ttl::TriangulationHelper::swappableEdge<TraitsType, DartType>(*it, true)) {
           // Dyn & Goren & Rippa 's notation:
           // The node assosiated with dart *it is denoted u_m. u_m has edges crossing the constraint
           // named w_1, ... , w_r . The other node to the edge assosiated with dart *it is w_s.
@@ -456,7 +457,7 @@ namespace ttl_constr {
               end = true;
             
             // This is the only place swapping is called when inserting a constraint
-            ttl::swapEdgeInList<TraitsType, DartType>(it,elist);
+            helper.swapEdgeInList<TraitsType, DartType>(it,elist);
             
             // If we, during look-ahead, found that dstart and/or dend were in the quadrilateral,
             // we update them.
@@ -512,6 +513,8 @@ namespace ttl_constr {
 
   }
 
+}; // End of ConstrainedTriangulation class
+
 }; // End of ttl_constr namespace scope
 
 
@@ -546,14 +549,14 @@ namespace ttl { // (extension)
   *   - \ref hed::TTLtraits::swapEdge "TraitsType::swapEdge" (DartType&)
   *
   *   \using
-  *   - ttl::optimizeDelaunay if \e optimize_delaunay is set to \c true
+  *   - optimizeDelaunay if \e optimize_delaunay is set to \c true
   *
   *   \par Assumes:
   *   - The constrained edge must be inside the existing triangulation (and it cannot
   *     cross the boundary of the triangulation).
   */
   template <class TraitsType, class DartType>
-    DartType insertConstraint(DartType& dstart, DartType& dend, bool optimize_delaunay) {
+    DartType TriangulationHelper::insertConstraint(DartType& dstart, DartType& dend, bool optimize_delaunay) {
     
     // Assumes:
     // - It is the users responsibility to avoid crossing constraints
@@ -567,8 +570,8 @@ namespace ttl { // (extension)
     // calls itself recursively. 
 
     // RECURSION
-    list<DartType> elist;
-    DartType next_start = ttl_constr::findCrossingEdges<TraitsType>(dstart, dend, elist);
+    std::list<DartType> elist;
+    DartType next_start = ttl_constr::ConstrainedTriangulation::findCrossingEdges<TraitsType>(dstart, dend, elist);
 
     // If there are no crossing edges (elist is empty), we assume that the constraint
     // is an existing edge.
@@ -583,7 +586,7 @@ namespace ttl { // (extension)
     // findCrossingEdges stops if it finds a node lying on the constraint.
     // A dart with this node as start node is returned
     // We call insertConstraint recursivly until the received dart is dend
-    if (!ttl::same_0_orbit(next_start, dend)) {
+    if (!same_0_orbit(next_start, dend)) {
 
 #ifdef DEBUG_TTL_CONSTR_PLOT
       cout << "RECURSION due to collinearity along constraint" << endl;
@@ -594,7 +597,7 @@ namespace ttl { // (extension)
     
     // Swap edges such that the constraint edge is present in the transformed triangulation.
     if (elist.size() > 0) // by Thomas Sevaldrud
-       ttl_constr::transformToConstraint<TraitsType>(dstart, next_start, elist);
+      ttl_constr::ConstrainedTriangulation::transformToConstraint<TraitsType>(dstart, next_start, elist);
     
 #ifdef DEBUG_TTL_CONSTR_PLOT
     cout << "size of elist = " << elist.size() << endl;
@@ -607,13 +610,13 @@ namespace ttl { // (extension)
 #endif
 
     // Optimize to constrained Delaunay triangulation if required.
-    typename list<DartType>::iterator end_opt = elist.end();
+    typename std::list<DartType>::iterator end_opt = elist.end();
     if (optimize_delaunay) {
 
       // Indicate that the constrained edge, which is the last element in the list,
       // should not be swapped
       --end_opt;
-      ttl::optimizeDelaunay<TraitsType, DartType>(elist, end_opt);
+      optimizeDelaunay<TraitsType, DartType>(elist, end_opt);
     }
 
     if(elist.size() == 0) // by Thomas Sevaldrud

pcbnew/ratsnest_data.cpp

@@ -240,7 +240,7 @@ void RN_NET::compute()
 
         return;
     }
-    else if( boardNodes.size() == 1 )   // This case is even simpler
+    else if( boardNodes.size() <= 1 )   // This case is even simpler
     {
         m_rnEdges.reset( new std::vector<RN_EDGE_PTR>( 0 ) );