[vtkusers] creating a vtkSpline to transform within a pipeline

[Anant Vemuri]

Hi David,

Thanks... that is exactly what I want to do. I was wondering, how does it
manage missing points.

Another thing, I tried to compile the test program on vtk documentation
website

http://vtk.org/gitweb?p=VTK.git;a=blob_plain;f=Filters/Hybrid/Testing/Cxx/TestBSplineWarp.cxx

and I get an error as,

error: ‘class vtkBSplineTransform’ has no member named ‘SetCoefficientData’.

Thanks,
Anant.

On Fri, Sep 14, 2012 at 2:37 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> Hi Anant,
>
> If you recompute the spline coefficients within the transform's
> Update() method, then it should provide the sort of pipeline behavior
> that you are looking for.  The following paper describes the VTK
> transform update mechanism:
> http://www.ncbi.nlm.nih.gov/pubmed/12631510
>
> I added a vtkBSplineTransform to VTK 5.10.  It might satisfy your
> needs, and if not, you might be able to re-use parts of it:
> http://hdl.handle.net/10380/3252
>
>  - David
>
> On Fri, Sep 14, 2012 at 4:02 AM, Anant Vemuri <ajar108 at gmail.com> wrote:
> > I am currently creating a spline using vtkSplineFilter. The points in the
> > spline are changing as new positions for points are generated. However,
> now
> > I want to put the position information into a vtkTransform and connect
> the
> > Spline being created within a pipeline so that, it gets updated when the
> the
> > transform changes.
> >
> > currently I am doing this whenever I get new positions. Is it possible to
> > put this in a pipeline so that the points are updated using a
> vtktransform
> > when the transform changes. In vtkTransform there is a function called
> > "MultiplyPoint" and "TransformPoint", however both are not indicated to
> be
> > pipelined.
> >
> > I am curious if anyone has tried to do this, or if anyone has
> suggestions on
> > this issue.
> >
> > myspline is a class containing vtkPoints, vtkPolyLine, vtkPolyData etc.
> >
> >
> >     //   In the constructor for my spline class
> >     _points       = vtkSmartPointer< vtkPoints >::New();
> >     _polyLine     = vtkSmartPointer< vtkPolyLine >::New();
> >     _cells        = vtkSmartPointer< vtkCellArray >::New();
> >     _polyData     = vtkSmartPointer< vtkPolyData >::New();
> >     _splineFilter = vtkSmartPointer< vtkSplineFilter >::New();
> >     _tubeFilter   = vtkSmartPointer< vtkTubeFilter >::New();
> >
> >     //   PIPELINE
> >     _cells->InsertNextCell(_polyLine);
> >     _polyData->SetPoints(_points);
> >     _polyData->SetLines(_cells);
> >     _splinefilter->SetInput( _polyData );
> >     _splinefilter->SetMaximumNumberOfSubdivisions( 48 );
> >     _tubeFilter->SetInputConnection( _splineFilter->GetOutputPort());
> >     _tubeFilter->SetNumberOfSides( 12 );
> >     _tubeFilter->SetRadius( 5.0 );
> >     _tubeFilter->SetCapping(true);
> >     _mapper->SetInputConnection( _tubeFilter->GetOutputPort() );
> >     _actor->SetMapper(_mapper);
> >     _actor->GetProperty()->SetLineWidth(4);
> >
> >     //----------------------------------------------------------------
> >     // Updating for new vtkpoints
> >
> >     // I want to put this part into the pipeline if possible so that
> >     // i can apply a vtkTransform to lets say the _points and the spline
> >     // gets updated automatically. The updated _points that I get are
> >
> >     // absolute positions so I cannot appl
> >     splineObj->getPoints()->Reset();
> >     splineObj->getPolyLine()->GetPointIds()->Reset();
> >     vtkIdType k = 0;
> >
> >     // __scanorder contains the order in which the points need to be put
> > into a spline
> >     // __positions contains the updated point locations
> >     for (int j = 0; j < __scanOrder.size(); j++)
> >     {
> >          unsigned int __idx = __scanOrder[i][j]-1;
> >          double &__coord = __positions[__idx]->getCoordinate();
> >
> >
> >
> splineObj->getPoints()->InsertNextPoint(__coord[0],__coord[1],__coord[2]);
> >          splineObj->getPolyLine()->GetPointIds()->InsertNextId( k );
> >          k++;
> >     }
> >     splineObj->getCellArray()->Reset();
> >     splineObj->getCellArray()->InsertNextCell(splineObj->getPolyLine());
> >     splineObj->getPolyData()->Modified();
> >
> >
> > Thank you,
> >
> > Anant.
>
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