[vtkusers] Draw out a cubical box on the rendering window

[David E DeMarle]

Hi Rashed,

You could use a vtkPlanes to define the bounding box beyond which the 
region can not grow. With each candidate point, test against the six 
planes and stop if outside. Look at vtkInteractorStyleRubberBandPick, 
vtkAreaPicker, and vtkFrustumExtractor. They will define the vtkPlanes 
for you, then you can adapt your region growing algorithm to use it.

cheers
Dave DeMarle