[vtkusers] update on the vtkImageStencil and vtkPolyData

[Anja Ende]

Hi everyone,

I finally managed to get it working.

The main key was use SetPolys instead of SetStripes with the vtkPolyData.

So, the code looks as follows:

//-----------------------------------------------------------------------------------
vtkFloatArray* pcoords = vtkFloatArray::New();
pcoords->SetNumberOfComponents(3);
// My polygon vertices
pcoords->SetNumberOfTuples(myimagePoints.size());
float * ptArray = pts;
for (int i=0; i<m_imagePoints.size(); i++)
{
                pcoords->SetTuple(i, ptArray);
                ptArray += 3;
}

// Create vtkPoints and assign pcoords as the internal data array.
vtkPoints* points = vtkPoints::New();
points->SetData(pcoords);
vtkPolyData* polydata = vtkPolyData::New();
polydata->SetPoints(points);

vtkCellArray* polys = vtkCellArray::New();
polys->InsertNextCell(m_imagePoints.size());
for (int i = 0; i < myimagePoints.size(); i++)
{
    polys->InsertCellPoint(i);
}

// vertices connect a polygon
polydata->SetPolys(polys);

vtkLinearExtrusionFilter* extrude = vtkLinearExtrusionFilter::New();
extrude->SetInput(polydata);
extrude->SetScaleFactor(1);
extrude->SetExtrusionTypeToNormalExtrusion();
extrude->SetVector(0, 0, 1);

vtkPolyDataToImageStencil* dataToStencil = vtkPolyDataToImageStencil::New();
dataToStencil->SetInput(extrude->GetOutput());

vtkImageStencil* stencil = vtkImageStencil::New();
stencil->SetInput(m_viewer->GetOutput());
stencil->SetStencil(dataToStencil->GetOutput());
stencil->ReverseStencilOff();
stencil->SetBackgroundValue(0);

stencil->Update();

//-----------------------------------------------------------------------------------

Also, the cell data does not need to be closed as VTK closes it with the
first cell automatically. Of course, probably it is always a good idea to
close it though!

The one nagging thing is that the extracted boundaries look pretty jagged.
Is there a way to set some sort of anti aliasing filter on the stencil
output?

I hope someone will find this of some use.

Cheers,

Anja
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