Method ShouldAddEdge3D

Filters/HyperTree/vtkHyperTreeGridFeatureEdges.cxx:277–332

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bool vtkHyperTreeGridFeatureEdges::ShouldAddEdge3D(
  vtkHyperTreeGridNonOrientedMooreSuperCursor* cursor, unsigned int edgeId)
{
  auto neighborVisible = [&cursor](unsigned int neighborId)
  { return cursor->HasTree(neighborId) && !cursor->IsMasked(neighborId); };

  auto neighborVisibleAndInf = [&cursor, &neighborVisible](unsigned int neighborId)
  { return neighborVisible(neighborId) && cursor->GetLevel(neighborId) < cursor->GetLevel(); };

  auto neighborVisibleAndLeaf = [&cursor, &neighborVisible](unsigned int neighborId)
  { return neighborVisible(neighborId) && cursor->IsLeaf(neighborId); };

  const unsigned int* neighborIds = MOORE_NEIGH_IDS_3D[edgeId];

  // For a given level, visible cells will generate edges only shared with other visible
  // neighboring leaf cells (by definition, such cell is necessarily a cell of same level).
  // Current visible cell will generate an edge if:
  // - no other cell sharing this edge is visible (we have a "corner" edge),
  // - only the "diagonal" cell sharing the edge is visible (the edge represents the
  //   intersection between the two cells),
  // - only 2 neighbouring cells sharing are visible (we have 3 cells sharing the edge,
  //   forming a 90 degrees angle).
  bool noneVisible = !neighborVisible(neighborIds[0]) && !neighborVisible(neighborIds[1]) &&
    !neighborVisible(neighborIds[2]);
  bool onlyDiag = !neighborVisible(neighborIds[0]) && neighborVisibleAndLeaf(neighborIds[1]) &&
    !neighborVisible(neighborIds[2]);
  bool onlyTwo = (!neighborVisible(neighborIds[0]) && neighborVisibleAndLeaf(neighborIds[1]) &&
                   neighborVisibleAndLeaf(neighborIds[2])) ||
    (neighborVisibleAndLeaf(neighborIds[0]) && !neighborVisible(neighborIds[1]) &&
      neighborVisibleAndLeaf(neighborIds[2])) ||
    (neighborVisibleAndLeaf(neighborIds[0]) && neighborVisibleAndLeaf(neighborIds[1]) &&
      !neighborVisible(neighborIds[2]));
  bool visibleShouldAdd = !cursor->IsMasked() && (noneVisible || onlyDiag || onlyTwo);

  // For a given level, masked cells will generate edges only shared with other visible
  // neighboring cells of inferior level (by definition, such cell is necessarily a leaf).
  // Current masked cell will generate an edge if:
  // - only one of the neighboring cells sharing the edge is visible (we have a "corner edge"),
  // - the 2 neighboring cells sharing the edge except the "diagonal" are visible (the edge
  //   represents the intersection between the 2 neighboring cells),
  // - all neighboring cells sharing the edge are visible (we have 3 cells sharing the edge,
  //   forming a 90 degrees angle).
  bool onlyOne = (neighborVisibleAndInf(neighborIds[0]) && !neighborVisible(neighborIds[1]) &&
                   !neighborVisible(neighborIds[2])) ||
    (!neighborVisible(neighborIds[0]) && neighborVisibleAndInf(neighborIds[1]) &&
      !neighborVisible(neighborIds[2])) ||
    (!neighborVisible(neighborIds[0]) && !neighborVisible(neighborIds[1]) &&
      neighborVisibleAndInf(neighborIds[2]));
  bool twoExceptDiag = neighborVisibleAndInf(neighborIds[0]) && !neighborVisible(neighborIds[1]) &&
    neighborVisibleAndInf(neighborIds[2]);
  bool allVisible = neighborVisibleAndInf(neighborIds[0]) &&
    neighborVisibleAndInf(neighborIds[1]) && neighborVisibleAndInf(neighborIds[2]);
  bool maskedShouldAdd = cursor->IsMasked() && (onlyOne || twoExceptDiag || allVisible);

  return visibleShouldAdd || maskedShouldAdd;
}

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