grid_objects_2d.h

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/*
 * Copyright (c) 2011-2015:  G-CSC, Goethe University Frankfurt
 * Author: Sebastian Reiter
 * 
 * This file is part of UG4.
 * 
 * UG4 is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 3 (as published by the
 * Free Software Foundation) with the following additional attribution
 * requirements (according to LGPL/GPL v3 §7):
 * 
 * (1) The following notice must be displayed in the Appropriate Legal Notices
 * of covered and combined works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (2) The following notice must be displayed at a prominent place in the
 * terminal output of covered works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (3) The following bibliography is recommended for citation and must be
 * preserved in all covered files:
 * "Reiter, S., Vogel, A., Heppner, I., Rupp, M., and Wittum, G. A massively
 *   parallel geometric multigrid solver on hierarchically distributed grids.
 *   Computing and visualization in science 16, 4 (2013), 151-164"
 * "Vogel, A., Reiter, S., Rupp, M., Nägel, A., and Wittum, G. UG4 -- a novel
 *   flexible software system for simulating pde based models on high performance
 *   computers. Computing and visualization in science 16, 4 (2013), 165-179"
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 */
 
#ifndef __H__UG__grid_objects_2d__
#define __H__UG__grid_objects_2d__
 
#include "../grid/grid.h"
#include "common/math/ugmath.h"
#include "common/assert.h"
#include "grid_objects_0d.h"
#include "grid_objects_1d.h"
 
namespace ug
{
 
 
enum FaceContainerSections
{
  CSFACE_NONE = -1,
  CSFACE_TRIANGLE = 0,
  CSFACE_QUADRILATERAL = 1,
  CSFACE_CONSTRAINED_TRIANGLE = 2,
  CSFACE_CONSTRAINED_QUADRILATERAL = 3,
  CSFACE_CONSTRAINING_TRIANGLE = 4,
  CSFACE_CONSTRAINING_QUADRILATERAL = 5,
 
  CSFACE_USER // always last
};
 
 
//  predeclarations
class Triangle;
class Quadrilateral;
class ConstrainedTriangle;
class ConstrainedQuadrilateral;
class ConstrainingTriangle;
class ConstrainingQuadrilateral;
 
//  NORMAL FACES
 
//  TriangleDescriptor
class UG_API TriangleDescriptor
{
  public:
    TriangleDescriptor()  {}
    TriangleDescriptor(const TriangleDescriptor& td);
    TriangleDescriptor(Vertex* v1, Vertex* v2, Vertex* v3);
 
    inline uint num_vertices() const          {return 3;}
    inline void set_vertex(uint index, Vertex* v) {m_vertex[index] = v;}
    inline Vertex* vertex(size_t index) const     {return m_vertex[index];}
 
  protected:
    Vertex* m_vertex[3];
};
 
 
 
//  CustomTriangle
 
template <class ConcreteTriangleType, class BaseClass,
      class RefTriType, class RefQuadType>
class UG_API CustomTriangle : public BaseClass
{
  public:
    static const size_t NUM_VERTICES = 3;
 
  public:
    CustomTriangle()  {}
    CustomTriangle(const TriangleDescriptor& td);
    CustomTriangle(Vertex* v1, Vertex* v2, Vertex* v3);
 
    virtual GridObject* create_empty_instance() const {return new ConcreteTriangleType;}
    virtual ReferenceObjectID reference_object_id() const {return ROID_TRIANGLE;}
 
    virtual Vertex* vertex(size_t index) const  {return m_vertices[index];}
    virtual Face::ConstVertexArray vertices() const   {return m_vertices;}
    virtual size_t num_vertices() const {return 3;}
 
    virtual EdgeDescriptor edge_desc(int index) const
      {return EdgeDescriptor(m_vertices[index], m_vertices[(index+1) % 3]);}
 
    virtual void edge_desc(int index, EdgeDescriptor& edOut) const
      {edOut.set_vertices(m_vertices[index], m_vertices[(index+1) % 3]);}
 
    virtual std::pair<GridBaseObjectId, int> get_opposing_object(Vertex* vrt) const;
 
    virtual bool refine(std::vector<Face*>& vNewFacesOut,
              Vertex** newFaceVertexOut,
              Vertex** newEdgeVertices,
              Vertex* newFaceVertex = NULL,
              Vertex** pSubstituteVertices = NULL,
              int snapPointIndex = -1);
 
    virtual bool is_regular_ref_rule(int edgeMarks) const;
 
    virtual bool collapse_edge(std::vector<Face*>& vNewFacesOut,
                int edgeIndex, Vertex* newVertex,
                Vertex** pSubstituteVertices = NULL);
 
    virtual bool collapse_edges(std::vector<Face*>& vNewFacesOut,
                std::vector<Vertex*>& vNewEdgeVertices,
                Vertex** pSubstituteVertices = NULL);
 
//  BEGIN Depreciated
    virtual void create_faces_by_edge_split(int splitEdgeIndex,
              Vertex* newVertex,
              std::vector<Face*>& vNewFacesOut,
              Vertex** pSubstituteVertices = NULL);
 
  protected:
    virtual void set_vertex(uint index, Vertex* pVrt) {m_vertices[index] = pVrt;}
 
  protected:
    Vertex* m_vertices[3];
};
 
 
 
//  Triangle
 
class UG_API Triangle :
  public CustomTriangle<Triangle, Face, Triangle, Quadrilateral>
{
  typedef CustomTriangle<Triangle, Face, Triangle, Quadrilateral> BaseClass;
  public:
    inline static bool type_match(GridObject* pObj) {return dynamic_cast<Triangle*>(pObj) != NULL;}
 
    Triangle() : BaseClass()  {}
    Triangle(const TriangleDescriptor& td) : BaseClass(td)  {}
    Triangle(Vertex* v1, Vertex* v2, Vertex* v3) : BaseClass(v1, v2, v3)  {}
 
    virtual int container_section() const {return CSFACE_TRIANGLE;}
 
  protected:
    virtual Edge* create_edge(int index)
      {
        return new RegularEdge(m_vertices[index], m_vertices[(index+1) % 3]);
      }
};
 
template <>
class geometry_traits<Triangle>
{
  public:
    typedef GenericGridObjectIterator<Triangle*, FaceIterator>      iterator;
    typedef ConstGenericGridObjectIterator<Triangle*, FaceIterator,
                              ConstFaceIterator>  const_iterator;
 
    typedef TriangleDescriptor Descriptor;  
    typedef Face  grid_base_object;
 
    enum
    {
      CONTAINER_SECTION = CSFACE_TRIANGLE,
      BASE_OBJECT_ID = FACE
    };
    static const ReferenceObjectID REFERENCE_OBJECT_ID = ROID_TRIANGLE;
};
 
typedef geometry_traits<Triangle>::iterator     TriangleIterator;
typedef geometry_traits<Triangle>::const_iterator ConstTriangleIterator;
 
 
 
//  QuadrilateralDescriptor
class UG_API QuadrilateralDescriptor
{
  public:
    QuadrilateralDescriptor() {}
    QuadrilateralDescriptor(const QuadrilateralDescriptor& qd);
    QuadrilateralDescriptor(Vertex* v1, Vertex* v2, Vertex* v3, Vertex* v4);
 
    inline uint num_vertices() const          {return 4;}
    inline void set_vertex(uint index, Vertex* v) {m_vertex[index] = v;}
    inline Vertex* vertex(size_t index) const     {return m_vertex[index];}
 
  protected:
    Vertex* m_vertex[4];
};
 
 
 
//  CustomQuadrilateral
 
template <class ConcreteQuadrilateralType, class BaseClass,
      class RefTriType, class RefQuadType>
class UG_API CustomQuadrilateral : public BaseClass
{
  public:
    static const size_t NUM_VERTICES = 4;
 
  public:
    using typename BaseClass::ConstVertexArray;
 
    CustomQuadrilateral() {}
    CustomQuadrilateral(const QuadrilateralDescriptor& qd);
    CustomQuadrilateral(Vertex* v1, Vertex* v2,
              Vertex* v3, Vertex* v4);
 
    virtual GridObject* create_empty_instance() const {return new ConcreteQuadrilateralType;}
    virtual ReferenceObjectID reference_object_id() const {return ROID_QUADRILATERAL;}
 
    virtual Vertex* vertex(size_t index) const  {return m_vertices[index];}
    virtual Face::ConstVertexArray vertices() const   {return m_vertices;}
    virtual size_t num_vertices() const {return 4;}
 
    virtual EdgeDescriptor edge_desc(int index) const
      {return EdgeDescriptor(m_vertices[index], m_vertices[(index+1) % 4]);}
 
    virtual void edge_desc(int index, EdgeDescriptor& edOut) const
      {edOut.set_vertices(m_vertices[index], m_vertices[(index+1) % 4]);}
 
 
 
    virtual bool get_opposing_side(EdgeVertices* e, EdgeDescriptor& edOut) const;
 
    virtual std::pair<GridBaseObjectId, int> get_opposing_object(Vertex* vrt) const;
 
    virtual bool refine(std::vector<Face*>& vNewFacesOut,
              Vertex** newFaceVertexOut,
              Vertex** newEdgeVertices,
              Vertex* newFaceVertex = NULL,
              Vertex** pSubstituteVertices = NULL,
              int snapPointIndex = -1);
 
    virtual bool is_regular_ref_rule(int edgeMarks) const;
    
    virtual bool collapse_edge(std::vector<Face*>& vNewFacesOut,
                int edgeIndex, Vertex* newVertex,
                Vertex** pSubstituteVertices = NULL);
 
    virtual bool collapse_edges(std::vector<Face*>& vNewFacesOut,
                std::vector<Vertex*>& vNewEdgeVertices,
                Vertex** pSubstituteVertices = NULL);
 
//  BEGIN Depreciated
    virtual void create_faces_by_edge_split(int splitEdgeIndex,
              Vertex* newVertex,
              std::vector<Face*>& vNewFacesOut,
              Vertex** pSubstituteVertices = NULL);
 
  protected:
    virtual void set_vertex(uint index, Vertex* pVrt) {m_vertices[index] = pVrt;}
 
  protected:
    Vertex* m_vertices[4];
};
 
 
 
//  Quadrilateral
 
class UG_API Quadrilateral :
  public CustomQuadrilateral<Quadrilateral, Face, Triangle, Quadrilateral>
{
  public:
    typedef CustomQuadrilateral<Quadrilateral, Face, Triangle, Quadrilateral>
        BaseClass;
 
    inline static bool type_match(GridObject* pObj)
    {return dynamic_cast<Quadrilateral*>(pObj) != NULL;}
 
    Quadrilateral() {}
    Quadrilateral(const QuadrilateralDescriptor& td) : BaseClass(td)  {}
    Quadrilateral(Vertex* v1, Vertex* v2,
            Vertex* v3, Vertex* v4) : BaseClass(v1, v2, v3, v4) {}
 
    virtual int container_section() const {return CSFACE_QUADRILATERAL;}
 
  protected:
    virtual Edge* create_edge(int index)
    {
      return new RegularEdge(m_vertices[index], m_vertices[(index+1) % 4]);
    }
};
 
template <>
class geometry_traits<Quadrilateral>
{
  public:
    typedef GenericGridObjectIterator<Quadrilateral*, FaceIterator>
        iterator;
    typedef ConstGenericGridObjectIterator<Quadrilateral*, FaceIterator,
                         ConstFaceIterator>
        const_iterator;
 
    typedef QuadrilateralDescriptor Descriptor; 
    typedef Face  grid_base_object;
 
    enum
    {
      CONTAINER_SECTION = CSFACE_QUADRILATERAL,
      BASE_OBJECT_ID = FACE
    };
    static const ReferenceObjectID REFERENCE_OBJECT_ID = ROID_QUADRILATERAL;
};
 
typedef geometry_traits<Quadrilateral>::iterator    QuadrilateralIterator;
typedef geometry_traits<Quadrilateral>::const_iterator  ConstQuadrilateralIterator;
 
 
 
//  CONSTRAINED FACES
 
//  ConstrainedFace
 
class UG_API ConstrainedFace : public Face
{
  public:
    inline static bool type_match(GridObject* pObj)
    {return dynamic_cast<ConstrainedFace*>(pObj) != NULL;}
 
    ConstrainedFace() : m_pConstrainingObject(NULL), m_parentBaseObjectId(-1) {}
    virtual ~ConstrainedFace()
    {
      if(m_pConstrainingObject)
        m_pConstrainingObject->remove_constraint_link(this);
    }
 
    inline void set_constraining_object(GridObject* pObj)
    {
      m_pConstrainingObject = pObj;
      if(pObj)
        m_parentBaseObjectId = pObj->base_object_id();
    }
 
    inline GridObject* get_constraining_object()  {return m_pConstrainingObject;}
 
    inline int get_parent_base_object_id()      {return m_parentBaseObjectId;}
    inline void set_parent_base_object_id(int id)
    {
      if((m_parentBaseObjectId != -1) && (m_parentBaseObjectId != id)){
        UG_THROW("Bad parent base object id specified! The given id"
            " has to match the id of the constraining object if that"
            " is present. Call this method only, if no constraining"
            " object has been set!");
      }
      m_parentBaseObjectId = id;
    }
 
    virtual bool is_constrained() const {return true;}
 
    virtual void remove_constraint_link(const Face* f)
    {
      if(m_pConstrainingObject == static_cast<const GridObject*>(f))
        m_pConstrainingObject = NULL;
    }
 
 
  protected:
    GridObject* m_pConstrainingObject;
    int     m_parentBaseObjectId;
};
 
 
//  ConstrainedTriangle
 
class UG_API ConstrainedTriangle :
  public CustomTriangle <ConstrainedTriangle, ConstrainedFace,
               ConstrainedTriangle, ConstrainedQuadrilateral>
{
  typedef CustomTriangle<ConstrainedTriangle, ConstrainedFace,
              ConstrainedTriangle, ConstrainedQuadrilateral>
      BaseTriangle;
 
  public:
    inline static bool type_match(GridObject* pObj) {return dynamic_cast<ConstrainedTriangle*>(pObj) != NULL;}
 
    ConstrainedTriangle() :
      BaseTriangle()  {}
 
    ConstrainedTriangle(const TriangleDescriptor& td) :
      BaseTriangle(td)  {}
 
    ConstrainedTriangle(Vertex* v1, Vertex* v2, Vertex* v3) :
      BaseTriangle(v1, v2, v3)  {}
 
    virtual int container_section() const {return CSFACE_CONSTRAINED_TRIANGLE;}
 
  protected:
    virtual Edge* create_edge(int index)
      {
        return new ConstrainedEdge(m_vertices[index], m_vertices[(index+1) % 3]);
      }
};
 
template <>
class geometry_traits<ConstrainedTriangle>
{
  public:
    typedef GenericGridObjectIterator<ConstrainedTriangle*, FaceIterator>
        iterator;
    typedef ConstGenericGridObjectIterator<ConstrainedTriangle*, FaceIterator,
                         ConstFaceIterator>
        const_iterator;
 
    typedef TriangleDescriptor Descriptor;  
    typedef Face  grid_base_object;
 
    enum
    {
      CONTAINER_SECTION = CSFACE_CONSTRAINED_TRIANGLE,
      BASE_OBJECT_ID = FACE
    };
    static const ReferenceObjectID REFERENCE_OBJECT_ID = ROID_TRIANGLE;
};
 
typedef geometry_traits<ConstrainedTriangle>::iterator      ConstrainedTriangleIterator;
typedef geometry_traits<ConstrainedTriangle>::const_iterator  ConstConstrainedTriangleIterator;
 
 
 
//  ConstrainedQuadrilateral
 
class UG_API ConstrainedQuadrilateral :
  public CustomQuadrilateral  <ConstrainedQuadrilateral, ConstrainedFace,
                 ConstrainedTriangle, ConstrainedQuadrilateral>
{
  typedef CustomQuadrilateral<ConstrainedQuadrilateral, ConstrainedFace,
                ConstrainedTriangle, ConstrainedQuadrilateral>
      BaseClass;
 
  public:
    inline static bool type_match(GridObject* pObj) {return dynamic_cast<ConstrainedQuadrilateral*>(pObj) != NULL;}
 
    ConstrainedQuadrilateral() : BaseClass()  {}
    ConstrainedQuadrilateral(const QuadrilateralDescriptor& qd) : BaseClass(qd) {}
    ConstrainedQuadrilateral(Vertex* v1, Vertex* v2,
                 Vertex* v3, Vertex* v4) : BaseClass(v1, v2, v3, v4)  {}
 
    virtual int container_section() const {return CSFACE_CONSTRAINED_QUADRILATERAL;}
 
  protected:
    virtual Edge* create_edge(int index)
      {
        return new ConstrainedEdge(m_vertices[index], m_vertices[(index+1) % 4]);
      }
};
 
 
template <>
class geometry_traits<ConstrainedQuadrilateral>
{
  public:
    typedef GenericGridObjectIterator<ConstrainedQuadrilateral*, FaceIterator>
        iterator;
    typedef ConstGenericGridObjectIterator<ConstrainedQuadrilateral*,
                         FaceIterator, ConstFaceIterator>
        const_iterator;
 
    typedef QuadrilateralDescriptor Descriptor; 
    typedef Face  grid_base_object;
 
    enum
    {
      CONTAINER_SECTION = CSFACE_CONSTRAINED_QUADRILATERAL,
      BASE_OBJECT_ID = FACE
    };
    static const ReferenceObjectID REFERENCE_OBJECT_ID = ROID_QUADRILATERAL;
};
 
typedef geometry_traits<ConstrainedQuadrilateral>::iterator     ConstrainedQuadrilateralIterator;
typedef geometry_traits<ConstrainedQuadrilateral>::const_iterator ConstConstrainedQuadrilateralIterator;
 
 
 
//  CONSTRAINING FACES
 
//  ConstrainingFace
 
class UG_API ConstrainingFace : public Face
{
 
  public:
    inline static bool type_match(GridObject* pObj) {return dynamic_cast<ConstrainingFace*>(pObj) != NULL;}
 
    virtual ~ConstrainingFace()
    {
      for(size_t i = 0; i < m_constrainedVertices.size(); ++i){
        m_constrainedVertices[i]->remove_constraint_link(this);
      }
 
      for(size_t i = 0; i < m_constrainedEdges.size(); ++i){
        m_constrainedEdges[i]->remove_constraint_link(this);
      }
 
      for(size_t i = 0; i < m_constrainedFaces.size(); ++i){
        m_constrainedFaces[i]->remove_constraint_link(this);
      }
    }
 
    virtual bool is_constraining() const          {return true;}
 
    inline void add_constrained_object(Vertex* pObj)
      {
        UG_ASSERT(!is_constrained_object(pObj),
              "vertex is already registered at constraining face");
        m_constrainedVertices.push_back(pObj);
      }
 
    inline void add_constrained_object(Edge* pObj)
      {
        UG_ASSERT(!is_constrained_object(pObj),
              "edge is already registered at constraining face");
        m_constrainedEdges.push_back(pObj);
      }
 
    inline void add_constrained_object(Face* pObj)
      {
        UG_ASSERT(!is_constrained_object(pObj),
              "face is already registered at constraining face");
        m_constrainedFaces.push_back(pObj);
      }
 
    inline bool is_constrained_object(Vertex* vrt)
      {
        std::vector<Vertex*>::iterator iter = find(m_constrainedVertices.begin(),
                              m_constrainedVertices.end(), vrt);
        return iter != m_constrainedVertices.end();
      }
 
    inline bool is_constrained_object(Edge* edge)
      {
        std::vector<Edge*>::iterator iter = find(m_constrainedEdges.begin(),
                              m_constrainedEdges.end(), edge);
        return iter != m_constrainedEdges.end();
      }
 
    inline bool is_constrained_object(Face* face)
      {
        std::vector<Face*>::iterator iter = find(m_constrainedFaces.begin(),
                            m_constrainedFaces.end(), face);
        return iter != m_constrainedFaces.end();
      }
 
    virtual void remove_constraint_link(const Vertex* vrt)
    {
      unconstrain_object(vrt);
    }
 
    virtual void remove_constraint_link(const Edge* e)
    {
      unconstrain_object(e);
    }
 
    virtual void remove_constraint_link(const Face* f)
    {
      unconstrain_object(f);
    }
 
    inline void unconstrain_object(const Vertex* vrt)
      {
        std::vector<Vertex*>::iterator iter = find(m_constrainedVertices.begin(),
                               m_constrainedVertices.end(), vrt);
        if(iter != m_constrainedVertices.end())
          m_constrainedVertices.erase(iter);
      }
 
    inline void unconstrain_object(const Edge* edge)
      {
        std::vector<Edge*>::iterator iter
          = find(m_constrainedEdges.begin(),
               m_constrainedEdges.end(), edge);
 
        if(iter != m_constrainedEdges.end())
          m_constrainedEdges.erase(iter);
      }
 
    inline void unconstrain_object(const Face* face)
      {
        std::vector<Face*>::iterator iter = find(m_constrainedFaces.begin(),
                            m_constrainedFaces.end(), face);
        if(iter != m_constrainedFaces.end())
          m_constrainedFaces.erase(iter);
      }
 
    inline void clear_constrained_vertices()  {m_constrainedVertices.clear();}
    inline void clear_constrained_edges()   {m_constrainedEdges.clear();}
    inline void clear_constrained_faces()   {m_constrainedFaces.clear();}
    inline void clear_constrained_objects()
      {
        clear_constrained_vertices();
        clear_constrained_edges();
        clear_constrained_faces();
      }
 
    inline size_t num_constrained_vertices() const
    {return m_constrainedVertices.size();}
 
    inline size_t num_constrained_edges() const
    {return m_constrainedEdges.size();}
 
    inline size_t num_constrained_faces() const
    {return m_constrainedFaces.size();}
 
 
    template <class TElem> size_t num_constrained() const;
 
 
    inline Vertex* constrained_vertex(size_t ind) const
      {
        UG_ASSERT(ind < m_constrainedVertices.size(), "bad index.");
        return m_constrainedVertices[ind];
      }
 
    inline Edge* constrained_edge(size_t ind) const
      {
        UG_ASSERT(ind < m_constrainedEdges.size(), "bad index.");
        return m_constrainedEdges[ind];
      }
 
    inline Face* constrained_face(size_t ind) const
      {
        UG_ASSERT(ind < m_constrainedFaces.size(), "bad index.");
        return m_constrainedFaces[ind];
      }
 
    template <class TElem> TElem* constrained(size_t ind) const;
 
  protected:
    std::vector<Vertex*>  m_constrainedVertices;
    std::vector<Edge*>    m_constrainedEdges;
    std::vector<Face*>    m_constrainedFaces;
};
 
 
 
//  ConstrainingTriangle
 
class UG_API ConstrainingTriangle :
  public CustomTriangle <ConstrainingTriangle, ConstrainingFace,
               ConstrainingTriangle, ConstrainingQuadrilateral>
{
  typedef CustomTriangle<ConstrainingTriangle, ConstrainingFace,
              ConstrainingTriangle, ConstrainingQuadrilateral>
      BaseTriangle;
 
  public:
    inline static bool type_match(GridObject* pObj)
    {return dynamic_cast<ConstrainingTriangle*>(pObj) != NULL;}
 
    ConstrainingTriangle() :
      BaseTriangle()  {reserve_memory();}
    ConstrainingTriangle(const TriangleDescriptor& td) :
      BaseTriangle(td)  {reserve_memory();}
    ConstrainingTriangle(Vertex* v1, Vertex* v2, Vertex* v3) :
      BaseTriangle(v1, v2, v3)  {reserve_memory();}
 
    virtual int container_section() const {return CSFACE_CONSTRAINING_TRIANGLE;}
 
  protected:
    void reserve_memory()
      {
        m_constrainedEdges.reserve(3);
        m_constrainedFaces.reserve(4);
      }
 
    virtual Edge* create_edge(int index)
      {
        return new RegularEdge(m_vertices[index], m_vertices[(index+1) % 3]);
      }
};
 
template <>
class geometry_traits<ConstrainingTriangle>
{
  public:
    typedef GenericGridObjectIterator<ConstrainingTriangle*, FaceIterator>
        iterator;
    typedef ConstGenericGridObjectIterator<ConstrainingTriangle*, FaceIterator,
                        ConstFaceIterator>
        const_iterator;
 
    typedef TriangleDescriptor Descriptor;  
    typedef Face  grid_base_object;
 
    enum
    {
      CONTAINER_SECTION = CSFACE_CONSTRAINING_TRIANGLE,
      BASE_OBJECT_ID = FACE
    };
    static const ReferenceObjectID REFERENCE_OBJECT_ID = ROID_TRIANGLE;
};
 
typedef geometry_traits<ConstrainingTriangle>::iterator
    ConstrainingTriangleIterator;
typedef geometry_traits<ConstrainingTriangle>::const_iterator
    ConstConstrainingTriangleIterator;
 
 
 
//  ConstrainingQuadrilateral
 
class UG_API ConstrainingQuadrilateral :
  public CustomQuadrilateral  <ConstrainingQuadrilateral, ConstrainingFace,
                 ConstrainingTriangle, ConstrainingQuadrilateral>
{
  typedef CustomQuadrilateral<ConstrainingQuadrilateral, ConstrainingFace,
                ConstrainingTriangle, ConstrainingQuadrilateral>
      BaseClass;
 
  public:
    inline static bool type_match(GridObject* pObj) {return dynamic_cast<ConstrainingQuadrilateral*>(pObj) != NULL;}
 
    ConstrainingQuadrilateral() :
      BaseClass() {reserve_memory();}
    ConstrainingQuadrilateral(const QuadrilateralDescriptor& qd) :
      BaseClass(qd) {reserve_memory();}
    ConstrainingQuadrilateral(Vertex* v1, Vertex* v2,
                  Vertex* v3, Vertex* v4) :
      BaseClass(v1, v2, v3, v4) {reserve_memory();}
 
    virtual int container_section() const {return CSFACE_CONSTRAINING_QUADRILATERAL;}
 
  protected:
    void reserve_memory()
      {
        m_constrainedVertices.reserve(1);
        m_constrainedEdges.reserve(4);
        m_constrainedFaces.reserve(4);
      }
 
    virtual Edge* create_edge(int index)
      {
        return new RegularEdge(m_vertices[index], m_vertices[(index+1) % 4]);
      }
};
 
template <>
class geometry_traits<ConstrainingQuadrilateral>
{
  public:
    typedef GenericGridObjectIterator<ConstrainingQuadrilateral*, FaceIterator>
        iterator;
 
    typedef ConstGenericGridObjectIterator<ConstrainingQuadrilateral*,
                      FaceIterator, ConstFaceIterator>
        const_iterator;
 
    typedef QuadrilateralDescriptor Descriptor; 
    typedef Face  grid_base_object;
 
    enum
    {
      CONTAINER_SECTION = CSFACE_CONSTRAINING_QUADRILATERAL,
      BASE_OBJECT_ID = FACE
    };
    static const ReferenceObjectID REFERENCE_OBJECT_ID = ROID_QUADRILATERAL;
};
 
typedef geometry_traits<ConstrainingQuadrilateral>::iterator
    ConstrainingQuadrilateralIterator;
typedef geometry_traits<ConstrainingQuadrilateral>::const_iterator
    ConstConstrainingQuadrilateralIterator;
 
 
}// end of namespace
 
#endif