[vtkusers] get points of a cutter

[Bill Lorensen]

Also, if you want the polylines to be continuous look at this example:
http://vtk.org/Wiki/VTK/Examples/ExtractPolyLinesFromPolyData

On Fri, Feb 5, 2010 at 5:15 AM, KS Jothybasu <jothybasu at gmail.com> wrote:
> I am bale to get the points like this
>
> cutter=vtk.vtkCutter()
>         cutter.SetCutFunction(plane)
>         cutter.SetInput(vtkObject.GetOutput())
>         cutter.Update()
>
>         out=cutter.GetOutput()
>         points=out.GetPoints()
>         NumPts=points.GetNumberOfPoints()
>         #print NumPts
>         OutlinePts=np.zeros([NumPts,3])
>         for n in range(0,NumPts,1):
>             OutlinePts[n,:]=np.round(points.GetPoint(n))
>
>
> As David said, you have to call the Update method.
>
> Jothy
>
> On Thu, Feb 4, 2010 at 7:04 PM, David Doria <daviddoria+vtk at gmail.com>
> wrote:
>>
>>
>> On Thu, Feb 4, 2010 at 11:46 AM, Eddy Cappeau
>> <ecappeau at phenix-systems.com> wrote:
>>>
>>> Hi,
>>>
>>> I'm new to VTK and I'v got a little problem with it.
>>> I want to cut a mesh with a plane and get the polyline of the
>>> intersection.
>>> The mesh come from a stl file loaded like this :
>>>
>>>    vtkSmartPointer<vtkSTLReader> reader =
>>> vtkSmartPointer<vtkSTLReader>::New();
>>>    reader->SetFileName("myfile.stl");
>>>
>>>    vtkSmartPointer<vtkPolyDataMapper> stlMapper =
>>> vtkSmartPointer<vtkPolyDataMapper>::New();
>>>    stlMapper->SetInputConnection(reader->GetOutputPort());
>>>
>>> I create a cutter like this :
>>>
>>>    vtkCutter * sliceCutter = vtkCutter::New();
>>>    sliceCutter->SetInput( reader->GetOutput() );
>>>    vtkPlane *slicePlane = vtkPlane::New();
>>>    slicePlane->SetOrigin(0.0,0.0,7.0);
>>>    slicePlane->SetNormal(0.0,0.0,1.0);
>>>
>>>    sliceCutter->SetCutFunction( slicePlane );
>>>
>>> I'v created a mapper and an actor for the mesh and the section, and i can
>>> visualize them both.
>>>
>>> So I try to retrieve the points like this :
>>>
>>>    vtkPolyData * testdata = sliceCutter->GetOutput();
>>>    vtkPoints * points = sliceCutter->GetOutput()->GetPoints();
>>>    int n = points->GetNumberOfPoints();
>>>
>>> But the vtkPoints is always NULL and  I don't understand why.
>>> How can I get those points ?
>>>
>>> thanks.
>>> _____
>>
>>
>> Sounds like you need to call Update on the cutter
>> sliceCutter->Update();
>>
>> Let me know if that works.
>> Thanks,
>>
>> David
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>
>
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