Method InsertTriInHash

Filters/Geometry/vtkDataSetSurfaceFilter.cxx:2404–2457

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//------------------------------------------------------------------------------
void vtkDataSetSurfaceFilter::InsertTriInHash(
  vtkIdType a, vtkIdType b, vtkIdType c, vtkIdType sourceId, vtkIdType vtkNotUsed(faceId) /*= -1*/)
{
  vtkIdType tmp;
  vtkFastGeomQuad *quad, **end;

  // Reorder to get smallest id in a.
  if (b < a && b < c)
  {
    tmp = a;
    a = b;
    b = c;
    c = tmp;
  }
  else if (c < a && c < b)
  {
    tmp = a;
    a = c;
    c = b;
    b = tmp;
  }
  // We can't put the second smallest in b because it might change the order
  // of the vertices in the final triangle.

  // Look for existing tri in the hash;
  end = this->QuadHash + a;
  quad = *end;
  while (quad)
  {
    end = &(quad->Next);
    // a has to match in this bin.
    if (quad->numPts == 3)
    {
      if ((b == quad->ptArray[1] && c == quad->ptArray[2]) ||
        (b == quad->ptArray[2] && c == quad->ptArray[1]))
      {
        // We have a match.
        quad->SourceId = -1;
        // That is all we need to do. Hide any tri shared by two or more cells.
        return;
      }
    }
    quad = *end;
  }

  // Create a new quad and add it to the hash.
  quad = this->NewFastGeomQuad(3);
  quad->Next = nullptr;
  quad->SourceId = sourceId;
  quad->ptArray[0] = a;
  quad->ptArray[1] = b;
  quad->ptArray[2] = c;
  *end = quad;
}

// Insert a polygon into the hash.
// Input: an array of vertex ids