[vtkusers] Deleting points form vtkPolyData object

[David Doria]

On Mon, Nov 2, 2009 at 12:24 PM, da <remywendy at gmail.com> wrote:
> Its not clear if you're adding multiple points or not...
>
> Given the code you've included, you're only inserting one point from the
> line
> m_Points->GetPoints()->InsertNextPoint(m_daPointPosition);
> and then deleting the second point (index 1, but you only have index 0),
> which would cause a null pointer exception?
>
>
> If you're adding multiple points in the lines of code that are not included,
> make sure to include them.
>
>
>
> On Mon, Nov 2, 2009 at 1:30 AM, Lodron, Gerald <Gerald.Lodron at joanneum.at>
> wrote:
>>
>> Hello,
>>
>> I stored a point list into the vtkPolyData object using these lines:
>>
>> //m_Points ... vtkPolyData Object pointer
>> //m_daPointPosition ... Three dimensional double array specifying x,y and
>> z coordinate of the point
>>
>> m_Points->GetPoints()->InsertNextPoint(m_daPointPosition);
>> m_Points->GetVerts()->InsertNextCell(1);
>>
>> m_Points->GetVerts()->InsertCellPoint(m_Points->GetPoints()->GetNumberOfPoints()-1);
>> m_Points->Update();
>>
>> This works fine, I also can visualize it. Now I want to delete a specific
>> point, e.g. the second point which was inserted, but I always get a null
>> pointer exception:
>>
>> m_Points->DeletePoint(1); //Null pointer exception
>> m_Points->DeleteCell(1);
>>
>> vtkCleanPolyData *Cleaner = vtkCleanPolyData::New();
>> Cleaner->SetInput(m_Points);
>> Cleaner->Update();
>>
>> m_Points = Cleaner->GetOutput();
>> m_Points->Update();
>> m_Points->BuildCells();
>> m_Points->BuildLinks();
>>
>> Cleaner = NULL; //Use smart pointers to delete
>>
>>
>> Have anybody a suggestion what i made false?
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>
> _______________________________________________
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>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
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>

I also get a segfault. Here is my example:

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>

int main(int argc, char *argv[])
{
  //create a set of points
  vtkSmartPointer<vtkPoints> Points = vtkSmartPointer<vtkPoints>::New();
  Points->InsertNextPoint ( 1.0, 0.0, 0.0 );
  Points->InsertNextPoint ( 0.0, 0.0, 0.0 );
  Points->InsertNextPoint ( 0.0, 1.0, 0.0 );

  vtkSmartPointer<vtkPolyData> Polydata = vtkSmartPointer<vtkPolyData>::New();
  Polydata->SetPoints(Points);

  vtkstd::cout << "Number of points: " <<
Polydata->GetNumberOfPoints() << vtkstd::endl;

  Polydata->DeletePoint(1);//segfault on this line

  vtkstd::cout << "Number of points: " <<
Polydata->GetNumberOfPoints() << vtkstd::endl;

  return 0;
}


Thanks,

David