[vtkusers] Export mesh of cutting plane

[kenichiro yoshimi]

Hi Fernando,

This will be accomplished by using vtkCleanUnstructuredGrid class
found in ParaView without triangulation. I have attached a simple
code.

Thanks

2017-09-29 16:37 GMT+09:00 Fernando Nellmeldin
<f.nellmeldin at open-engineering.com>:
> Hello. That did the job! (although I get a triangle mesh while the initial
> surface was full of sliced hexahedron (quads).
>
> Thank you!
>
> On 29 September 2017 at 04:05, kenichiro yoshimi <rccm.kyoshimi at gmail.com>
> wrote:
>>
>> Hello,
>>
>> Using vtkDataSetTriangleFilter is a simple way which allows you to
>> convert polyData to unstructuredGrid. Something like this (VTK-8.0.0):
>> ---
>>   // Create cutter
>>   vtkSmartPointer<vtkCutter> cutter =
>>     vtkSmartPointer<vtkCutter>::New();
>>   cutter->SetCutFunction(plane);
>>   cutter->SetInputConnection(model->GetOutputPort());
>>
>>   // Convert polyData to unstructuredGrid
>>   vtkSmartPointer<vtkDataSetTriangleFilter> triFilter =
>>     vtkSmartPointer<vtkDataSetTriangleFilter>::New();
>>   triFilter->SetInputConnection(cutter->GetOutputPort());
>>   triFilter->Update();
>>
>>   vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
>>     vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
>>   writer->SetFileName("unstructuredGrid.vtu");
>>   writer->SetInputConnection(triFilter->GetOutputPort());
>>   writer->Write();
>> ---
>>
>> Regards
>>
>> 2017-09-28 23:43 GMT+09:00 Fernando Nellmeldin
>> <f.nellmeldin at open-engineering.com>:
>> > Hello.
>> > I have a method to cut a volume in a vtkUnstructuredGrid given a
>> > vtkPlane.
>> > I'm using vtkTableBasedClipDataSet to extract half of the model, also as
>> > vtkUnstructuredGrid. This is working.
>> >
>> > Now, I would like to obtain ONLY the surface of the cut, than means: I
>> > want
>> > a vtkUnstructuredGrid with the nodes and faces being on the surface of
>> > the
>> > cut.
>> > How can this be achieved?
>> >
>> > I tried using vtkCutter with vtkStripper but the mesh I get doesn't have
>> > any
>> > cells, only the points and their associated data.
>> >
>> > Here's how my code looks like.
>> >
>> > Thank You!
>> >
>> > vtkSmartPointer<vtkUnstructuredGrid> model =
>> > vtkSmartPointer<vtkUnstructuredGrid>::New();
>> > // fill the ugrid ...
>> >
>> > // Create The Plane to cut
>> > vtkSmartPointer<vtkPlane> plane = vtkSmartPointer<vtkPlane>::New();
>> > plane->SetOrigin(0.0, 0.0, 0.0);
>> > plane->SetNormal(1.0, 0, 0);
>> >
>> > // Code to cut the model in half
>> > vtkSmartPointer<vtkTableBasedClipDataSet> clipDataSet =
>> > vtkSmartPointer<vtkTableBasedClipDataSet>::New();
>> > clipDataSet->SetClipFunction(plane);
>> > clipDataSet->InsideOutOn();
>> > clipDataSet->GenerateClippedOutputOn();
>> > clipDataSet->SetInputConnection(model->GetProducerPort());
>> > clipDataSet->Update();
>> >
>> > // This has half the model, this is Ok but not what I want
>> > vtkSmartPointer<vtkUnstructuredGrid> halfModel =
>> > clipDataSet->GetOutput();
>> >
>> > ////****////
>> > // BEGINS code not working to extract the surface of the cut
>> > vtkSmartPointer<vtkCutter> cutter = vtkSmartPointer<vtkCutter>::New();
>> > cutter->SetCutFunction(plane);
>> > cutter->SetInputConnection(model->GetProducerPort());
>> > cutter->Update();
>> >
>> > vtkSmartPointer<vtkStripper> stripper =
>> > vtkSmartPointer<vtkStripper>::New();
>> > stripper->SetInputConnection(cutter->GetOutputPort());
>> > stripper->Update();
>> >
>> > vtkSmartPointer<vtkPolyData> pd = vtkSmartPointer<vtkPolyData>::New();
>> > pd->SetPoints(stripper->GetOutput()->GetPoints());
>> > pd->SetPolys(stripper->GetOutput()->GetLines());
>> >
>> > vtkSmartPointer<vtkUnstructuredGrid> clipped =
>> > vtkSmartPointer<vtkUnstructuredGrid>::New();
>> > clipped->ShallowCopy(pd);
>> >
>> > // Here I see that there is no Cells
>> > clipped->Print(std::cout);
>> >
>> > // ENDS code to extract the surface of the cut
>> > ////****////
>> >
>> > // Write the unstructured grid
>> > vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
>> > vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
>> > writer->SetFileName("d:/unstructuredGrid.vtu");
>> > writer->SetInput(clipped);
>> > writer->SetDataModeToAscii();
>> > writer->Write();
>> > // file doesnt have any cell, only points and pointdata
>> >
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>
>
>
>
> --
> Fernando NELLMELDIN
> Software Engineer
> _______________________________________________________________
>
> Open Engineering s.a.
>
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> Tel: +32.4.353.30.34
>
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