[vtk-developers] vtkStructuredGrid::GetCell(i,j,k)

[David Doria]

On Fri, Feb 19, 2010 at 11:48 AM, Francois Bertel <
francois.bertel at kitware.com> wrote:

> Bbviously the documentation is wrong. Cell extent can be negative.
>
> a cell (voxel) of extent (i,j,k) is a cube with points going from
> extent (i,j,k) to  extent (i+1,j+1,k+1).
>

Ok, here is the updated description paragraph (using extents instead of
indices starting at 0:

// The order and number of points must match that specified by the
dimensions
// of the grid. The point order increases in i fastest (from
extent[0]<=i<=extent[1]),
// then j (extent[2]<=j<=extent[3]), then k (extent[4]<=k<=extent[5]). The
number of
// points is dims[0]*dims[1]*dims[2]. The same is true for the cells of the
// grid. The order and number of cells must match that specified by the
// dimensions of the grid. The cell order increases in i fastest (from
// extent[0]<=i<=(extent[1]-1)), then j (extent[2]<=j<=(extent[3]-1)),
// then k (extent[4]<=k<=(extent[5]-1)).
// The number of cells is (dims[0]-1)*(dims[1]-1)*(dims[2]-1).

And here is the function:

vtkCell* vtkStructuredGrid::GetCell(int i, int j, int k, bool
adjustForExtent)
{
  int extent[6];
  this->GetExtent(extent);

  if(i < extent[0] || i > extent[1] ||
     j < extent[2] || j > extent[3] ||
     k < extent[4] || k > extent[5])
    {
    return NULL; // out of bounds!
    }

  int pos[3];
  pos[0] = i;
  pos[1] = j;
  pos[2] = k;

  vtkIdType id;

  if(adjustForExtent)
    {
    id = vtkStructuredData::ComputeCellIdForExtent(extent, pos);
    }
  else
    {
    int dim[3];
    this->GetDimensions(dim);
    id = vtkStructuredData::ComputeCellId(dim, pos);
    }

  return this->GetCell(id);
}

If someone could please check it out and give me the go ahead to commit that
would be great.

Thanks,

David
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