[vtkusers] Color the faces of vtkUnstructuredGridGeometryFilter

[Gishara Indeewarie]

Hi all,

I am creating a vtkUnstructuredGrid and extract its faces using
vtkUnstructuredGridGeometryFilter.
I want to add colors to each face of the resulting unstructured grid.
Is there a way that we can assign scalar data to faces?
I tried with getCellData method but it did not give any output.
Below is my code:

#include <vtkVersion.h>
#include <vtkCellArray.h>
#include <vtkPoints.h>
#include <vtkHexahedron.h>
#include <vtkUnstructuredGrid.h>

#include <vtkSmartPointer.h>
#include <vtkDataSetMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkCellData.h>
#include <vtkCell.h>
#include <vtkLookupTable.h>
#include <vtkFloatArray.h>
#include <vtkUnstructuredGridGeometryFilter.h>
#include <vtkPointData.h>

int main(int, char *[])
{
  // Setup the coordinates of eight points
  // (the two faces must be in counter clockwise order as viewd from the
outside)
  double P0[3] = {0.0, 0.0, 0.0};
  double P1[3] = {1.0, 0.0, 0.0};
  double P2[3] = {1.0, 1.0, 0.0};
  double P3[3] = {0.0, 1.0, 0.0};
  double P4[3] = {0.0, 0.0, 1.0};
  double P5[3] = {1.0, 0.0, 1.0};
  double P6[3] = {1.0, 1.0, 1.0};
  double P7[3] = {0.0, 1.0, 1.0};


  // Create the points
  vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(P0);
  points->InsertNextPoint(P1);
  points->InsertNextPoint(P2);
  points->InsertNextPoint(P3);
  points->InsertNextPoint(P4);
  points->InsertNextPoint(P5);
  points->InsertNextPoint(P6);
  points->InsertNextPoint(P7);

  // Create a hexahedron from the points
  vtkSmartPointer<vtkHexahedron> hex =
    vtkSmartPointer<vtkHexahedron>::New();
  hex->GetPointIds()->SetId(0,0);
  hex->GetPointIds()->SetId(1,1);
  hex->GetPointIds()->SetId(2,2);
  hex->GetPointIds()->SetId(3,3);
  hex->GetPointIds()->SetId(4,4);
  hex->GetPointIds()->SetId(5,5);
  hex->GetPointIds()->SetId(6,6);
  hex->GetPointIds()->SetId(7,7);

  // Add the hexahedron to a cell array
  vtkSmartPointer<vtkCellArray> hexs =
    vtkSmartPointer<vtkCellArray>::New();
  hexs->InsertNextCell(hex);

  vtkSmartPointer<vtkFloatArray> cellData =
    vtkSmartPointer<vtkFloatArray>::New();
for (int i = 0; i < 6; i++)
    {
 cellData->InsertNextValue(i + 1);
    }
  // Add the points and hexahedron to an unstructured grid
  vtkSmartPointer<vtkUnstructuredGrid> uGrid =
    vtkSmartPointer<vtkUnstructuredGrid>::New();
  uGrid->SetPoints(points);
  uGrid->InsertNextCell(hex->GetCellType(), hex->GetPointIds());

  vtkSmartPointer<vtkUnstructuredGridGeometryFilter> geometryFilter =
    vtkSmartPointer<vtkUnstructuredGridGeometryFilter>::New();

  geometryFilter->SetInput(uGrid);
  geometryFilter->Update();

  vtkUnstructuredGrid* grid2 = geometryFilter->GetOutput();
 /grid2->GetCellData()->SetScalars(cellData);
  // Create a lookup table to map cell data to colors
  grid2->se
  vtkSmartPointer<vtkLookupTable> lut =
    vtkSmartPointer<vtkLookupTable>::New();
  int tableSize = 1;
  lut->SetNumberOfTableValues(tableSize);
  lut->Build();


  // Visualize
  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  mapper->SetInputConnection(grid2->GetProducerPort());
#else
  mapper->SetInputData(uGrid);
#endif
   mapper->SetScalarRange(0, tableSize - 1);
  mapper->SetLookupTable(lut);

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  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(.2, .3, .4);

  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

Thanks in advance.
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