[vtk-developers] implementing vtkPolyData::ComputeBounds() ?
sebastien at barre.nom.fr
Sat Jul 29 12:49:36 EDT 2000
I was wondering why vtkPolyData::ComputeBounds() is not implemented ? Is it
OK if I take care of this ?
Rational : suppose that given a polygonal object A, I use a vtkClipPolyData
filter to extract two other polygonal objects B, and C, which will have
different topologies (and most probably different extents).
If I query the bounds of B and C using GetBounds(), or use vtkOulineFilter
to display very simple bounding boxes, I'll get ... the bounds of A. This
is no surprise because both A, B and C share the *same* points (vtkPoints),
and as A, B, C are vtkPolyData derived from vtkPointSet, GetBounds() use
vtkPointSet::ComputeBounds(), which computes the bounds by iterating over
I'm a bit confused with that. If the only "visible" thing (or real data) is
defined in vtkPolyData by its cells, I guess ComputeBounds() should reflect
this too, am I right ?
I used to circumvent the problem by defining a function in Tcl, but it's
soooooooo slow (GetCellsBounds() is not available in Tcl).
Therefore, may I implement this vtkPolyData::ComputeBounds() feature ? The
bounds will be much more accurate. I'm asking first because GetBounds() is
used in so many files that I may have missed the "big picture".
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