OCCT

// Created on: 1995-03-06
// Created by: Laurent PAINNOT
// Copyright (c) 1995-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#include <Poly_Connect.hxx>

#include <NCollection_IncAllocator.hxx>
#include <Poly_Triangulation.hxx>

// this structure records one of the edges starting from a node
struct polyedge
{
  polyedge* next;  // the next edge in the list
  int       nt[2]; // the two adjacent triangles
  int       nn[2]; // the two adjacent nodes
  int       nd;    // the second node of the edge
  DEFINE_STANDARD_ALLOC
};

//=================================================================================================

Poly_Connect::Poly_Connect()
    : mytr(0),
      myfirst(0),
      mynode(0),
      myothernode(0),
      mysense(false),
      mymore(false)
{
}

//=================================================================================================

Poly_Connect::Poly_Connect(const occ::handle<Poly_Triangulation>& theTriangulation)
    : myTriangulation(theTriangulation),
      myTriangles(1, theTriangulation->NbNodes()),
      myAdjacents(1, 6 * theTriangulation->NbTriangles()),
      mytr(0),
      myfirst(0),
      mynode(0),
      myothernode(0),
      mysense(false),
      mymore(false)
{
  Load(theTriangulation);
}

//=================================================================================================

void Poly_Connect::Load(const occ::handle<Poly_Triangulation>& theTriangulation)
{
  myTriangulation = theTriangulation;
  mytr            = 0;
  myfirst         = 0;
  mynode          = 0;
  myothernode     = 0;
  mysense         = false;
  mymore          = false;

  const int aNbNodes = myTriangulation->NbNodes();
  const int aNbTris  = myTriangulation->NbTriangles();
  {
    const int aNbAdjs = 6 * aNbTris;
    if (myTriangles.Length() != aNbNodes)
    {
      myTriangles.Resize(1, aNbNodes, false);
    }
    if (myAdjacents.Length() != aNbAdjs)
    {
      myAdjacents.Resize(1, aNbAdjs, false);
    }
  }

  myTriangles.Init(0);
  myAdjacents.Init(0);

  // We first build an array of the list of edges connected to the nodes
  // create an array to store the edges starting from the vertices
  NCollection_Array1<polyedge*> anEdges(1, aNbNodes);
  anEdges.Init(nullptr);
  // use incremental allocator for small allocations
  occ::handle<NCollection_IncAllocator> anIncAlloc = new NCollection_IncAllocator();

  // loop on the triangles
  NCollection_Vec3<int> aTriNodes;
  NCollection_Vec2<int> anEdgeNodes;
  for (int aTriIter = 1; aTriIter <= aNbTris; ++aTriIter)
  {
    // get the nodes
    myTriangulation->Triangle(aTriIter).Get(aTriNodes[0], aTriNodes[1], aTriNodes[2]);

    // Update the myTriangles array
    myTriangles.SetValue(aTriNodes[0], aTriIter);
    myTriangles.SetValue(aTriNodes[1], aTriIter);
    myTriangles.SetValue(aTriNodes[2], aTriIter);

    // update the edge lists
    for (int aNodeInTri = 0; aNodeInTri < 3; ++aNodeInTri)
    {
      const int aNodeNext = (aNodeInTri + 1) % 3; // the following node of the edge
      if (aTriNodes[aNodeInTri] < aTriNodes[aNodeNext])
      {
        anEdgeNodes[0] = aTriNodes[aNodeInTri];
        anEdgeNodes[1] = aTriNodes[aNodeNext];
      }
      else
      {
        anEdgeNodes[0] = aTriNodes[aNodeNext];
        anEdgeNodes[1] = aTriNodes[aNodeInTri];
      }

      // edge from node 0 to node 1 with node 0 < node 1
      // insert in the list of node 0
      polyedge* ced = anEdges[anEdgeNodes[0]];
      for (; ced != nullptr; ced = ced->next)
      {
        // the edge already exists
        if (ced->nd == anEdgeNodes[1])
        {
          // just mark the adjacency if found
          ced->nt[1] = aTriIter;
          ced->nn[1] = aTriNodes[3 - aNodeInTri - aNodeNext]; // the third node
          break;
        }
      }

      if (ced == nullptr)
      {
        // create the edge if not found
        ced                     = (polyedge*)anIncAlloc->Allocate(sizeof(polyedge));
        ced->next               = anEdges[anEdgeNodes[0]];
        anEdges[anEdgeNodes[0]] = ced;
        ced->nd                 = anEdgeNodes[1];
        ced->nt[0]              = aTriIter;
        ced->nn[0]              = aTriNodes[3 - aNodeInTri - aNodeNext]; // the third node
        ced->nt[1]              = 0;
        ced->nn[1]              = 0;
      }
    }
  }

  // now complete the myAdjacents array
  int anAdjIndex = 1;
  for (int aTriIter = 1; aTriIter <= aNbTris; ++aTriIter)
  {
    // get the nodes
    myTriangulation->Triangle(aTriIter).Get(aTriNodes[0], aTriNodes[1], aTriNodes[2]);

    // for each edge in triangle
    for (int aNodeInTri = 0; aNodeInTri < 3; ++aNodeInTri)
    {
      const int aNodeNext = (aNodeInTri + 1) % 3; // the following node of the edge
      if (aTriNodes[aNodeInTri] < aTriNodes[aNodeNext])
      {
        anEdgeNodes[0] = aTriNodes[aNodeInTri];
        anEdgeNodes[1] = aTriNodes[aNodeNext];
      }
      else
      {
        anEdgeNodes[0] = aTriNodes[aNodeNext];
        anEdgeNodes[1] = aTriNodes[aNodeInTri];
      }

      // edge from node 0 to node 1 with node 0 < node 1
      // find in the list of node 0
      const polyedge* ced = anEdges[anEdgeNodes[0]];
      while (ced->nd != anEdgeNodes[1])
      {
        ced = ced->next;
      }

      // Find the adjacent triangle
      const int l = ced->nt[0] == aTriIter ? 1 : 0;

      myAdjacents.SetValue(anAdjIndex, ced->nt[l]);
      myAdjacents.SetValue(anAdjIndex + 3, ced->nn[l]);
      ++anAdjIndex;
    }
    anAdjIndex += 3;
  }

  // destroy the edges array - can be skipped when using NCollection_IncAllocator
  /*for (int aNodeIter = anEdges.Lower(); aNodeIter <= anEdges.Upper(); ++aNodeIter)
  {
    for (polyedge* anEdgeIter = anEdges[aNodeIter]; anEdgeIter != NULL;)
    {
      polyedge* aTmp = anEdgeIter->next;
      anIncAlloc->Free (anEdgeIter);
      anEdgeIter = aTmp;
    }
  }*/
}

//=================================================================================================

void Poly_Connect::Initialize(const int N)
{
  mynode  = N;
  myfirst = Triangle(N);
  mytr    = myfirst;
  mysense = true;
  mymore  = (myfirst != 0);
  myPassedTr.Clear();
  myPassedTr.Add(mytr);
  if (mymore)
  {
    int i, no[3];
    myTriangulation->Triangle(myfirst).Get(no[0], no[1], no[2]);
    for (i = 0; i < 3; i++)
    {
      if (no[i] == mynode)
      {
        break;
      }
    }
    myothernode = no[(i + 2) % 3];
  }
}

//=================================================================================================

void Poly_Connect::Next()
{
  int i, j;
  int n[3];
  int t[3];
  Triangles(mytr, t[0], t[1], t[2]);
  if (mysense)
  {
    for (i = 0; i < 3; i++)
    {
      if (t[i] != 0)
      {
        myTriangulation->Triangle(t[i]).Get(n[0], n[1], n[2]);
        for (j = 0; j < 3; j++)
        {
          if ((n[j] == mynode) && (n[(j + 1) % 3] == myothernode))
          {
            mytr        = t[i];
            myothernode = n[(j + 2) % 3];
            mymore      = !myPassedTr.Contains(mytr);
            myPassedTr.Add(mytr);
            return;
          }
        }
      }
    }
    // sinon, depart vers la gauche.
    myTriangulation->Triangle(myfirst).Get(n[0], n[1], n[2]);
    for (i = 0; i < 3; i++)
    {
      if (n[i] == mynode)
      {
        break;
      }
    }
    myothernode = n[(i + 1) % 3];
    mysense     = false;
    mytr        = myfirst;
    Triangles(mytr, t[0], t[1], t[2]);
  }
  if (!mysense)
  {
    for (i = 0; i < 3; i++)
    {
      if (t[i] != 0)
      {
        myTriangulation->Triangle(t[i]).Get(n[0], n[1], n[2]);
        for (j = 0; j < 3; j++)
        {
          if ((n[j] == mynode) && (n[(j + 2) % 3] == myothernode))
          {
            mytr        = t[i];
            myothernode = n[(j + 1) % 3];
            mymore      = !myPassedTr.Contains(mytr);
            myPassedTr.Add(mytr);
            return;
          }
        }
      }
    }
  }
  mymore = false;
}