[vtkusers] Grid intersections?

[Andrea Gavana]

Hi all,

   I have a 3D unstructured grid (a reservoir representation) and I
am faced with a challenge for which I don't even know if a solution
exists. If it exists, I don't know where to look for it. I've googled
around quite a bit but got zero clues.
Based on 3 user inputs (width, height, depth), I would like to
construct some kind of parallelepiped and then I would like to move it
(in x, y, z directions sequentially) inside my 3D unstructred grid:
for evey move, I would like to know which cells of my 3D grid are
intersected by this parallelepiped. Actually, the parallelepiped will
be distorted, as the 3D grid is not orthogonal (is a corner point
grid), so the problem looks like a 3D unstructured grid that
intersects a smaller 3D unstructured grid, and I would like to find
out which cells of the bigger grid are intersected by the smaller one.
It is like a moving 3D window inside the bigger grid.
Does anyone have a suggestion or a comment to share?

Thank you for every hint.

-- 
Andrea.

"Imagination Is The Only Weapon In The War Against Reality."
http://xoomer.virgilio.it/infinity77/