[vtkusers] write vtkPolyData with colors from vtkPolyDataMapper

[Jian Cheng]

Hi,

I would like to write a vtkPolydata into .vtk file with the colors from
vtkPolyDataMapper.
However the written .vtk file has  incorrect color which is different
from the rendered color.
Please see the following small code.
Your help will be appreciated.

best,
Jian Cheng

#include <vtkSmartPointer.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

#include <vtkLookupTable.h>
#include <vtkFloatArray.h>
#include <vtkCellData.h>
#include <vtkPolyData.h>
#include <vtkPlaneSource.h>

#include <vtkPolyDataWriter.h>
#include <vtkSmartPointer.h>
 
int main(int , char *[])
{
  // Provide some geometry
  int resolution = 3;
  vtkSmartPointer<vtkPlaneSource> aPlane =
    vtkSmartPointer<vtkPlaneSource>::New();
  aPlane->SetXResolution(resolution);
  aPlane->SetYResolution(resolution);

  // Create cell data
  vtkSmartPointer<vtkFloatArray> cellData =
    vtkSmartPointer<vtkFloatArray>::New();
  for (int i = 0; i < resolution * resolution; i++)
    {
    cellData->InsertNextValue(i + 1);
    }

  // Create a lookup table to map cell data to colors
  vtkSmartPointer<vtkLookupTable> lut =
    vtkSmartPointer<vtkLookupTable>::New();
  int tableSize = std::max(resolution*resolution + 1, 10);
  lut->SetNumberOfTableValues(tableSize);
  lut->Build();

  // Fill in a few known colors, the rest will be generated if needed
  lut->SetTableValue(0     , 0     , 0     , 0, 1);  //Black
  lut->SetTableValue(1, 0.8900, 0.8100, 0.3400, 1); // Banana
  lut->SetTableValue(2, 1.0000, 0.3882, 0.2784, 1); // Tomato
  lut->SetTableValue(3, 0.9608, 0.8706, 0.7020, 1); // Wheat
  lut->SetTableValue(4, 0.9020, 0.9020, 0.9804, 1); // Lavender
  lut->SetTableValue(5, 1.0000, 0.4900, 0.2500, 1); // Flesh
  lut->SetTableValue(6, 0.5300, 0.1500, 0.3400, 1); // Raspberry
  lut->SetTableValue(7, 0.9804, 0.5020, 0.4471, 1); // Salmon
  lut->SetTableValue(8, 0.7400, 0.9900, 0.7900, 1); // Mint
  lut->SetTableValue(9, 0.2000, 0.6300, 0.7900, 1); // Peacock

  aPlane->Update(); // Force an update so we can set cell data
  aPlane->GetOutput()->GetCellData()->SetScalars(cellData);

  // Setup actor and mapper
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(aPlane->GetOutputPort());
  mapper->SetScalarRange(0, tableSize - 1);
  mapper->SetLookupTable(lut);

  mapper->Update();

  vtkSmartPointer<vtkPolyDataWriter> writer =
vtkSmartPointer<vtkPolyDataWriter>::New();
  writer->SetFileName( "aa.vtk" );
  writer->SetInputData( mapper->GetInput() );
  writer->Write();


  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
 
  // Setup render window, renderer, and interactor
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
      vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderer->AddActor(actor);
  renderer->SetBackground(.1,.2,.3);
  renderWindow->Render();
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}