[vtkusers] Export mesh of cutting plane

[kenichiro yoshimi]

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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