[vtkusers] Blanking, GetScalars AND vtk4.0

[Stephane Lemaire]

Hello Everyone,

I try to get cells blanking using scalar values but I
get an error message I don't understand. Here is the
source code :

#include "vtkRenderer.h"
#include "vtkQuartzRenderWindow.h"
#include "vtkQuartzRenderWindowInteractor.h"
#include "vtkDataSetMapper.h"
#include "vtkActor.h"
#include "vtkStructuredGridReader.h"
#include "vtkStructuredGrid.h"
#include "vtkFloatArray.h"
#include "vtkLookupTable.h"

int main( int argc, char *argv[] )
{

  int npoints;
  float valuerange[2];
  float rho_i;

vtkRenderer *ren1 = vtkRenderer::New();
vtkQuartzRenderWindow *renWin =
vtkQuartzRenderWindow::New();
    renWin->AddRenderer(ren1);
vtkQuartzRenderWindowInteractor *iren =
vtkQuartzRenderWindowInteractor::New();
    iren->SetRenderWindow(renWin);
vtkStructuredGridReader *reader =
vtkStructuredGridReader::New();
    reader->SetFileName("data.vtk");
    reader->SetScalarsName("pressure");
    reader->Update();
    reader->GetOutput()->GetScalarRange(valuerange);
   
npoints=(reader->GetOutput())->GetNumberOfPoints();
    reader->SetScalarsName("rho");

vtkFloatArray *rho = vtkFloatArray::New();
(reader->GetOutput())->GetPointData()->SetActiveScalars("rho");
   
rho=reader->GetOutput()->GetPointData()->GetScalars();
    for (int i=0; i <  npoints; i++)
     {rho_i=rho->GetComponent(i,0);
      if (rho_i < 0.04)
       {reader->GetOutput()->BlankingOn();
        reader->GetOutput()->BlankPoint(i);}
      }

vtkLookupTable *lut = vtkLookupTable::New();
    lut->SetNumberOfColors(30);
    lut->SetHueRange(0.6667,0.);
    lut->Build();

vtkDataSetMapper *dataMapper =
vtkDataSetMapper::New();
    reader->SetScalarsName("pressure");
    dataMapper->SetInput(reader->GetOutput());
   
dataMapper->SetScalarRange(valuerange[0],valuerange[1]);
    dataMapper->SetLookupTable(lut);

    dataMapper->Update();
    printf("%.4f\n",valuerange[0]);
    printf("%.4f\n",valuerange[1]);
    printf("%.5i\n",npoints);

vtkActor *dataActor = vtkActor::New();
    dataActor->SetMapper(dataMapper);
    ren1->AddActor(dataActor);
    ren1->SetBackground(0.1,0.2,0.4);
    renWin->Render();
    iren->Start();

return 0;
}


and here is the error message :

type `vtkFloatArray' is not a base type for type
`vtkDataArray'

The problem seems to be linked with the command
vtkFloatArray *rho=vtkFloatArray::New() because if I
replace it with vtkDataArray
rho=reader->GetOutput()->GetPointData()->GetScalars()it
works !! So I guess I can't directly create rho with
the former command (why ?).

The second issue is with Blanking command, I verified
that the points I wanted to be blanked were blanked
effectively (with IsPointVisible method) but I don't
see any difference on screen so should I use an
additional filter ?

Any help will be really appreciated !

Stephane.

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