path: root/inc/Poly_CoherentTriangulation.hxx

// File:      Poly_CoherentTriangulation.hxx
// Created:   24.11.07 14:24
// Author:    Alexander GRIGORIEV
// Copyright: Open Cascade 2007


#ifndef Poly_CoherentTriangulation_HeaderFile
#define Poly_CoherentTriangulation_HeaderFile

#include <Handle_Poly_Triangulation.hxx>
#include <Poly_CoherentNode.hxx>
#include <Poly_CoherentTriangle.hxx>
#include <Poly_CoherentLink.hxx>
#include <NCollection_Vector.hxx>

class Handle_Poly_CoherentTriangulation;
class Poly_CoherentTriangulation;
template <class A> class NCollection_List;

typedef NCollection_Vector<Poly_CoherentTriangle>::Iterator
                                Poly_BaseIteratorOfCoherentTriangle;
typedef NCollection_Vector<Poly_CoherentNode>::Iterator
                                Poly_BaseIteratorOfCoherentNode;
typedef NCollection_Vector<Poly_CoherentLink>::Iterator
                                Poly_BaseIteratorOfCoherentLink;

/**
 * Triangulation structure that allows to:
 * <ul>
 * <li>Store the connectivity of each triangle with up to 3 neighbouring ones
 *     and with the corresponding 3rd nodes on them,</li>
 * <li>Store the connectivity of each node with all triangles that share this
 *     node</li>
 * <li>Add nodes and triangles to the structure,</li>
 * <li>Find all triangles sharing a single or a couple of nodes</li>
 * <li>Remove triangles from structure</li>
 * <li>Optionally create Links between pairs of nodes according to the current
 *     triangulation. 
 * <li>Convert from/to Poly_Triangulation structure.</li>
 * </ul>
 * This class is useful for algorithms that need to analyse and/or edit a
 * triangulated mesh -- for example for mesh refining. The connectivity model
 * follows the idea that all Triangles in a mesh should have coherent orientation
 * like on a surface of a solid body. Connections between more than 2 triangles
 * are not suppoorted.
 * @section Poly_CoherentTriangulation Architecture
 * The data types used in this structure are:
 * <ul>
 * <li><b>Poly_CoherentNode</b>: Inherits go_XYZ therefore provides the full
 *     public API of gp_XYZ. Contains references to all incident triangles. You
 *     can add new nodes but you cannot remove existing ones. However each node
 *     that has no referenced triangle is considered as "free" (use the method
 *     IsFreeNode() to check this). Free nodes are not available to further
 *     processing, particularly they are not exported in Poly_Triangulation.
 * </li>
 * <li><b>Poly_CoherentTriangle</b>: Main data type. Refers three Nodes, three
 *     connected Triangles, three opposite (connected) Nodes and three Links.
 *     If there is boundary then 1, 2 or 3 references to Triangles/connected
 *     Nodes/Links are assigned to NULL (for pointers) or -1 (for integer
 *     node index).
 *     <br>
 *     You can find a triangle by one node using its triangle iterator or by
 *     two nodes - creating a temporary Poly_CoherentLink and calling the method
 *     FindTriangle().
 *     <br>
 *     Triangles can be removed but they are never deleted from
 *     the containing array. Removed triangles have all nodes equal to -1. You
 *     can use the method IsEmpty() to check that.
 * </li>
 * <li><b>Poly_CoherentLink</b>: Auxiliary data type. Normally the array of
 *     Links is empty, because for many algorithms it is sufficient to define
 *     only Triangles. You can explicitly create the Links at least once,
 *     calling the method ComputeLinks(). Each Link is oriented couple of
 *     Poly_CoherentNode (directed to the ascending Node index). It refers
 *     two connected triangulated Nodes - on the left and on the right,
 *     therefore a Poly_CoherentLink instance refers the full set of nodes
 *     that constitute a couple of connected Triangles. A boundary Link has
 *     either the first (left) or the second (right) connected node index
 *     equal to -1.
 *     <br>
 *     When the array of Links is created, all subsequent calls to AddTriangle
 *     and RemoveTriangle try to preserve the connectivity Triangle-Link in
 *     addition to the connectivity Triangle-Triangle. Particularly, new Links
 *     are created by method AddTriangle() and existing ones are removed by
 *     method RemoveTriangle(), in each case whenever necessary.
 *     <br>
 *     Similarly to Poly_CoherentTriangle, a Link can be removed but not
 *     destroyed separately from others. Removed Link can be recogniosed using
 *     the method IsEmpty(). To destroy all Links, call the method ClearLinks(),
 *     this method also nullifies Link references in all Triangles. 
 * </li>
 * All objects (except for free Nodes and empty Triangles and Links) can be
 * visited by the corresponding Iterator. Direct access is provided only for
 * Nodes (needed to resolve Node indexed commonly used as reference). Triangles
 * and Links can be retrieved by their index only internally, the public API
 * provides only references or pointers to C++ objects. If you need a direct
 * access to Triangles and Links, you can subclass Poly_CoherentTriangulation
 * and use the protected API for your needs.
 * <br>
 * Memory management: All data objects are stored in NCollection_Vector
 * containers that prove to be efficient for the performance. In addition
 * references to triangles are stored in ring lists, with an instance of such
 * list per Poly_CoherentNode. These lists are allocated in a memory allocator
 * that is provided in the constructor of Poly_CoherentTriangulation. By default
 * the standard OCCT allocator (aka NCollection_BaseAllocator) is used. But if
 * you need to increase the performance you can use NCollection_IncAllocator
 * instead.
 * </ul>
 */

class Poly_CoherentTriangulation : public Standard_Transient
{
 public:
  /**
   * Subclass Iterator - allows to iterate all triangles skipping those that
   * have been removed.
   */
  class IteratorOfTriangle : public Poly_BaseIteratorOfCoherentTriangle
  {
  public:
    //! Constructor
    Standard_EXPORT IteratorOfTriangle
                          (const Handle_Poly_CoherentTriangulation& theTri);
    //! Make step
    Standard_EXPORT virtual void Next ();
  };

  /**
   * Subclass Iterator - allows to iterate all nodes skipping the free ones.
   */
  class IteratorOfNode : public Poly_BaseIteratorOfCoherentNode
  {
  public:
    //! Constructor
    Standard_EXPORT IteratorOfNode
                        (const Handle_Poly_CoherentTriangulation& theTri);
    //! Make step
    Standard_EXPORT virtual void Next ();
  };

  /**
   * Subclass Iterator - allows to iterate all links skipping invalid ones.
   */
  class IteratorOfLink : public Poly_BaseIteratorOfCoherentLink
  {
  public:
    //! Constructor
    Standard_EXPORT IteratorOfLink
                        (const Handle_Poly_CoherentTriangulation& theTri);
    //! Make step
    Standard_EXPORT virtual void Next ();
  };

  //! Couple of integer indices (used in RemoveDegenerated()).
  struct TwoIntegers
  {
    Standard_Integer myValue[2];
    TwoIntegers() {}
    TwoIntegers(Standard_Integer i0, Standard_Integer i1) {
      myValue[0] = i0; myValue[1] = i1;
    }
  };

 public:
  // ---------- PUBLIC METHODS ----------


  /**
   * Empty constructor.
   */
  Standard_EXPORT Poly_CoherentTriangulation
                (const Handle_NCollection_BaseAllocator& theAlloc = 0L);

  /**
   * Constructor. It does not create Links, you should call ComputeLinks
   * following this constructor if you need these links.
   */
  Standard_EXPORT Poly_CoherentTriangulation
                (const Handle_Poly_Triangulation&        theTriangulation,
                 const Handle_NCollection_BaseAllocator& theAlloc = 0L);

  /**
   * Destructor.
   */
  Standard_EXPORT virtual ~Poly_CoherentTriangulation ();

  /**
   * Create an instance of Poly_Triangulation from this object.
   */
  Standard_EXPORT Handle_Poly_Triangulation
                                   GetTriangulation () const;

  /**
   * Find and remove degenerated triangles in Triangulation.
   * @param theTol
   *   Tolerance for the degeneration case. If any two nodes of a triangle have
   *   the distance less than this tolerance, this triangle is considered
   *   degenerated and therefore removed by this method.
   * @param pLstRemovedNode
   *   Optional parameter. If defined, then it will receive the list of arrays
   *   where the first number is the index of removed node and the seond -
   *   the index of remaining node to which the mesh was reconnected.
   */
  Standard_EXPORT Standard_Boolean RemoveDegenerated
                        (const Standard_Real             theTol,
                         NCollection_List<TwoIntegers> * pLstRemovedNode = 0L);

  /**
   * Create a list of free nodes. These nodes may appear as a result of any
   * custom mesh decimation or RemoveDegenerated() call. This analysis is
   * necessary if you support additional data structures based on the
   * triangulation (e.g., edges on the surface boundary).
   * @param lstNodes
   *   <tt>[out]</tt> List that receives the indices of free nodes.
   */
  Standard_EXPORT Standard_Boolean GetFreeNodes
                        (NCollection_List<Standard_Integer>& lstNodes) const;

  /**
   * Query the index of the last node in the triangulation
   */
  inline Standard_Integer          MaxNode      () const
  { return myNodes.Length() - 1; }

  /**
   * Query the index of the last triangle in the triangulation
   */
  inline Standard_Integer          MaxTriangle  () const
  { return myTriangles.Length() - 1; }

  /**
   * Set the Deflection value as the parameter of the given triangulation.
   */
  inline void                      SetDeflection(const Standard_Real theDefl)
  { myDeflection = theDefl; }

  /**
   * Query the Deflection parameter (default value 0. -- if never initialized)
   */
  inline Standard_Real             Deflection   () const
  { return myDeflection; }

  /**
   * Initialize a node
   * @param thePoint
   *   3D Coordinates of the node.
   * @param iN
   *   Index of the node. If negative (default), the node is added to the
   *   end of the current array of nodes.
   * @return
   *   Index of the added node.
   */
  Standard_EXPORT Standard_Integer SetNode      (const gp_XYZ&          thePnt,
                                                 const Standard_Integer iN= -1);

  /**
   * Get the node at the given index 'i'.
   */
  inline const Poly_CoherentNode&  Node         (const Standard_Integer i) const
  { return myNodes.Value(i); }

  /**
   * Get the node at the given index 'i'.
   */
  inline Poly_CoherentNode&        ChangeNode   (const Standard_Integer i) 
  { return myNodes.ChangeValue(i); }

  /**
   * Query the total number of active nodes (i.e. nodes used by 1 or more
   * triangles)
   */
  Standard_EXPORT Standard_Integer NNodes       () const;

  /**
   * Get the triangle at the given index 'i'.
   */
  inline const Poly_CoherentTriangle&  Triangle (const Standard_Integer i) const
  { return myTriangles.Value(i); }

  /**
   * Query the total number of active triangles (i.e. triangles that refer
   * nodes, non-empty ones)
   */
  Standard_EXPORT Standard_Integer NTriangles   () const;

  /**
   * Query the total number of active Links.
   */
  Standard_EXPORT Standard_Integer NLinks       () const;  

  /**
   * Removal of a single triangle from the triangulation.
   */
  Standard_EXPORT Standard_Boolean RemoveTriangle(Poly_CoherentTriangle& theTr);

  /**
   * Removal of a single link from the triangulation.
   */
  Standard_EXPORT void             RemoveLink   (Poly_CoherentLink& theLink);

  /**
   * Add a triangle to the triangulation.
   * @return
   *   Pointer to the added triangle instance or NULL if an error occurred.
   */
  Standard_EXPORT Poly_CoherentTriangle *
                                   AddTriangle  (const Standard_Integer iNode0,
                                                 const Standard_Integer iNode1,
                                                 const Standard_Integer iNode2);

  /**
   * Replace nodes in the given triangle.
   * @return
   *   True if operation succeeded.
   */
  Standard_EXPORT Standard_Boolean ReplaceNodes
                    (Poly_CoherentTriangle& theTriangle,
                     const Standard_Integer iNode0,
                     const Standard_Integer iNode1,
                     const Standard_Integer iNode2);

  /**
   * Add a single link to triangulation, based on a triangle and its side index.
   * This method does not check for coincidence with already present links.
   * @param theTri
   *   Triangle that contains the link to be added.
   * @param theConn
   *   Index of the side (i.e., 0, 1 0r 2) defining the added link.
   */
  Standard_EXPORT Poly_CoherentLink *
                                   AddLink (const Poly_CoherentTriangle& theTri,
                                            const Standard_Integer    theConn);

  /**
   * Find one or two triangles that share the given couple of nodes.
   * @param theLink
   *   Link (in fact, just a couple of nodes) on which the triangle is
   *   searched.
   * @param pTri
   *   <tt>[out]</tt> Array of two pointers to triangle. pTri[0] stores the
   *   triangle to the left of the link, while pTri[1] stores the one to the
   *   right of the link.
   * @return
   *   True if at least one triangle is found and output as pTri.
   */ 
  Standard_EXPORT Standard_Boolean FindTriangle
                                (const Poly_CoherentLink&       theLink,
                                 const Poly_CoherentTriangle*   pTri[2]) const;

  /**
   * (Re)Calculate all links in this Triangulation.
   */
  Standard_EXPORT Standard_Integer ComputeLinks ();

  /**
   * Clear all Links data from the Triangulation data.
   */
  Standard_EXPORT void             ClearLinks   ();

  /**
   * Query the allocator of elements, this allocator can be used for other
   * objects 
   */
  inline const Handle_NCollection_BaseAllocator&
                                Allocator       () const
  {
    return myAlloc;
  }
  /**
   * Create a copy of this Triangulation, using the given allocator.
   */
  Standard_EXPORT Handle_Poly_CoherentTriangulation  Clone
                (const Handle_NCollection_BaseAllocator& theAlloc) const;

  /**
   * Debugging output.
   */
  Standard_EXPORT void             Dump         (Standard_OStream&) const;

 protected:
  // ---------- PROTECTED METHODS ----------



 protected:
  // ---------- PROTECTED FIELDS ----------

  NCollection_Vector<Poly_CoherentTriangle> myTriangles;
  NCollection_Vector<Poly_CoherentNode>     myNodes;
  NCollection_Vector<Poly_CoherentLink>     myLinks;
  Handle_NCollection_BaseAllocator          myAlloc;
  Standard_Real                             myDeflection;

 public:
// Declaration of CASCADE RTTI
DEFINE_STANDARD_RTTI (Poly_CoherentTriangulation)

  friend class IteratorOfTriangle;
  friend class IteratorOfNode;
  friend class IteratorOfLink;
};

#include <Handle_Poly_CoherentTriangulation.hxx>

#endif