Method EstablishNeighbors

Filters/Geometry/vtkStructuredAMRGridConnectivity.cxx:1613–1693

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void vtkStructuredAMRGridConnectivity::EstablishNeighbors(int i, int j)
{
  int ext1[6]; /* extent for grid i */
  int ext2[6]; /* extent for grid j */

  // STEP 0: Compute the level difference between the two grids
  int levelDiff = std::abs((this->GridLevels[j] - this->GridLevels[i]));

  // STEP 1: If this is a balanced refinement, check the level difference
  if (this->BalancedRefinement)
  {
    if (levelDiff > 1)
    {
      // If the refinement is balanced, adjacent grids are guaranteed to have
      // a level difference of 1, hence, we skip grids that have bigger level
      // difference.
      return;
    }
  } // END if balanced refinement

  // NOTE: To establish neighboring connectivity, the grids must be coarsened
  // or refined at the same level. By convention, we always normalize to the
  // level of grid j.
  int normalizedLevel = this->GridLevels[j];

  // STEP 2: Get normalized extents, i.e., extents at the same level
  if (this->GridLevels[i] == this->GridLevels[j])
  {
    // Grids at the same level, connectivity can be determined directly
    // by acquiring each grid extent.
    this->GetGridExtent(i, ext1);
    this->GetGridExtent(j, ext2);
  } // END if the grids are at the same level
  else if (this->GridLevels[i] < this->GridLevels[j])
  {
    // Grid "i" is coarser than grid "j"
    this->GetRefinedExtent(i, this->GridLevels[i], this->GridLevels[j], ext1);
    this->GetGridExtent(j, ext2);
  }
  else if (this->GridLevels[i] > this->GridLevels[j])
  {
    // Grid "i" is finer than grid "j"
    this->GetCoarsenedExtent(i, this->GridLevels[i], this->GridLevels[j], ext2);
    this->GetGridExtent(j, ext2);
  }
  else
  {
    // Code should not reach here!
    vtkErrorMacro("Code should not reach here!");
  }

  // STEP 3: Get the whole extent at the normalized level
  int myWholeExtent[6];
  this->GetWholeExtentAtLevel(normalizedLevel, myWholeExtent);

  // STEP 4: Use vtkStructuredGridConnectivity to establish neighbors
  vtkStructuredGridConnectivity* gridConnectivity = vtkStructuredGridConnectivity::New();
  gridConnectivity->SetWholeExtent(myWholeExtent);