[vtkusers] How to draw contourlines on a Cone?

[John Platt]

Hi,

Where have you defined the data to be contoured?

You could try adding some point scalars - 

  vtkPolyData* conePolyData = cone->GetOutput();
  conePolyData->Update();
  vtkDoubleArray* scalars = vtkDoubleArray::New();
  conePolyData->GetPointData()->SetScalars( scalars );
  scalars->Delete();

  const int numPts = conePolyData->GetNumberOfPoints();
  for ( int ii = 0; ii < numPts; ++ii )
  {
     double* xyz = conePolyData->GetPoints()->GetPoint( ii );
     double x = xyz[0]; // -1.5 to + 1.5
     scalars->InsertTuple( ii, &x );
  }

Then create the mapper and set the scalar range -

  coneMapper->SetScalarRange( -1.5, 1.5 );

HTH

John.

-----Original Message-----
From: vtkusers-bounces+jcplatt=dsl.pipex.com at vtk.org
[mailto:vtkusers-bounces+jcplatt=dsl.pipex.com at vtk.org] On Behalf Of
beth at portugalmail.pt
Sent: 27 November 2006 12:21
To: vtkusers at vtk.org
Cc: ecarvalho at dsi.uminho.pt
Subject: [vtkusers] How to draw contourlines on a Cone?

Hi,

I would like to draw a cone, and according Y coordinate values, paint it

differently. On other words, I want to create contour lines/surfaces on
the 
cone. My idea is to use a cone to map distribution values of my data
(lower to 
higher values, accumulative distribution). So it should be made of
several 
slices with different colors and thickness.

My piece of code that is not working:

 vtkConeSource *cone = vtkConeSource::New();
  cone->SetHeight( 3.0 ); // I suppose it y value goes from 0 to 3.0...
  cone->SetRadius( 1.0 );
  cone->SetResolution( 10 );
  
  vtkContourFilter* contour = vtkContourFilter::New();
  contour->SetInputConnection(cone->GetOutputPort());
  contour->SetValue  ( 1, 0.1); // try to create 2 contours, on position
y=0.1 
and 0.2
  contour->SetValue  ( 2, 0.2);

  vtkPolyDataMapper *contourMapper = vtkPolyDataMapper::New();
  contourMapper->SetInputConnection( contour->GetOutputPort() );

  vtkActor *contourActor = vtkActor::New();
  contourActor->SetMapper( contourMapper );

// usual rendering stuff...

My goal is to control the contour generation according to y coordinate
value 
on the cone, but it's not working at all!

Thanks for any help/tip!

Best regards,

Elizabeth



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