[vtkusers] Problem using vtkMergePoints

[Bill Lorensen]

You need to call InitPointInsertion before inserting points.


On Fri, Aug 28, 2009 at 11:23 PM, Alex
Malyushytskyy<alexmalvtk at gmail.com> wrote:
> VTK documentation states that :
>
> "vtkPointLocator has two distinct methods of interaction. In the first
> method, you supply it with a dataset, and it operates on the points in
> the dataset. In the second method, you supply it with an array of
> points, and the object operates on the array."
>
> I need the second method, because I require control over building
> procedure and dealing with complex composite data structure which
> should not be affected.
> (I need to build the unique set of the points and the map which can
> provide mapping from the unique point to the points  in vtkPolyData
> (which don't have to be unique) in composite data set).
>
> But could not find the way how it can be implemented.
>
> I assumed that I can just use InsertPoint or InsertUniquePoint to
> insert points, but
> both functions rely on the vtkMergePoints::HashTable not to be NULL;
>
> For example the following code
>
>        vtkSmartPointer<vtkMergePoints> merge = vtkSmartPointer<vtkMergePoints>::New();
>
>        double x0[3];
>        x0[0]= 0.;
>        x0[1]= 0.;
>        x0[2]= 0.;
>
>        merge->InsertPoint(0, x0);
>
>
> will throw exception at vtkpointlocator.cxx, function InsertPoint line:
>  if ( ! (bucket = this->HashTable[idx]) )
>
> because HashTable == NULL
>
>
> Do I miss something, and the vtkMergePoints has to be supplied by  the
> point array in other way?
> Attempts to call Initialize or Build on empty vtkMergePoints  did not help.
> (MSVC 2005 SP2, WindowsXp 64 bit, VTK 5.4.2 stable, QT4.4.3 )
>
> I probably could build map using STL or QHash instead ( it is pretty
> straightforward, because I need to remove duplicate points only), but
> it seems the natural to use VTK  methods.
> If anybody could confirm that the way I was going to use it is legal,
> I probably could create the patches, but until then I can only assume
> I am missing the correct usage.
>
> Any help is appreciated.
>
> Regards,
>    Alex
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