[vtkusers] Need help with vtkTubeFilter

[Alex Lear]

I have successfully used the vtkTubeFilter in the past but I am trying a new
way of doing things and have encountered a problem.  In the most simple case
I am creating a line from two points and applying scalar values to the
points.  I then run it into the vtkTubeFilter.  I would like to scale the
tube radius by scalar value so I set that up too.  However, the radius does
not seem to be varying by scalar value.  I am not quite sure if the scalar
values are being set right or if the problem is somewhere else.
I am including a small c++ test program code to show the problem, maybe
someone can see why it isn't varying the radius.  The development is in
Windows.

Thanks,
Alex Lear


// tube_test.cpp
//

#include "stdafx.h"
#include "vtk.h"

#define RADIAL_RESOLUTION 10

int main(int argc, char* argv[])
{
  vtkPolyData *polydata = vtkPolyData::New();
  vtkPoints *points = vtkPoints::New();
  vtkCellArray *line = vtkCellArray::New();
  vtkScalars *linescalars = vtkScalars::New();
  vtkTubeFilter *Tube = vtkTubeFilter::New();
  vtkPolyDataMapper *Tubemapper = vtkPolyDataMapper::New();
  vtkActor *TubeActor = vtkActor::New();
  vtkRenderWindowInteractor *interactor = vtkRenderWindowInteractor::New();
    vtkRenderer *renderer = vtkRenderer::New();
  vtkRenderWindow *renWin = vtkRenderWindow::New();

  points->SetNumberOfPoints(2);
  points->InsertPoint (0,0,0,0);
  points->InsertPoint (1,100,100,100);

  line->InsertNextCell(2);
  line->InsertCellPoint(0);
  line->InsertCellPoint(1);

  linescalars->SetDataTypeToFloat();
  linescalars->SetNumberOfScalars(2);
  linescalars->InsertScalar(0,1);  // I set the two scalars very different
to ...
  linescalars->InsertScalar(1,100); // ... be an obvious difference in
radius.

  polydata->SetPoints(points);
  polydata->SetLines(line);
  polydata->GetPointData()->SetScalars(linescalars);

  Tube->SetInput(polydata);
  Tube->SetVaryRadiusToVaryRadiusByScalar();
  Tube->SetNumberOfSides(RADIAL_RESOLUTION);

  Tubemapper->SetInput(Tube->GetOutput());
  TubeActor->SetMapper(Tubemapper);

  renWin->AddRenderer(renderer);
  renderer->AddActor(TubeActor);
  interactor->SetRenderWindow(renWin);

  renWin->Render();
  interactor->Start();
 return 0;
}