VTK/Examples/Cxx/Visualization/LabelContours

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
 
#include <vtkXMLPolyDataReader.h>
#include <vtkContourFilter.h>
#include <vtkStripper.h>
#include <vtkPolyDataMapper.h>
#include <vtkLabeledDataMapper.h>
#include <vtkPlaneSource.h>
#include <vtkLookupTable.h>
#include <vtkProperty.h>
#include <vtkActor.h>
#include <vtkActor2D.h>
 
#include <vtkCellArray.h>
#include <vtkPoints.h>
#include <vtkPointData.h>
#include <vtkDataArray.h>
#include <vtkDoubleArray.h>
 
#include <vtkMath.h>
 
int main (int argc, char *argv[])
{
  int pointThreshold = 10;
 
  vtkSmartPointer<vtkPolyData> polyData =
    vtkSmartPointer<vtkPolyData>::New();
  vtkSmartPointer<vtkContourFilter> contours =
    vtkSmartPointer<vtkContourFilter>::New();
 
  // If a file is present, read it, otherwise generate some random
  // scalars on a plane
  if (argc > 1)
    {
    vtkSmartPointer<vtkXMLPolyDataReader> reader =
      vtkSmartPointer<vtkXMLPolyDataReader>::New();
    reader->SetFileName(argv[1]);
    reader->Update();
 
    double range[2];
    reader->GetOutput()->GetScalarRange(range);
    polyData = reader->GetOutput();
 
    std::cout << "range: " << range[0] << ", " << range[1] << std::endl;
    contours->SetValue(0, (range[1] + range[0]) / 2.0);
 
    contours->SetInputConnection(reader->GetOutputPort());
    if (argc == 3)
      {
      contours->SetValue(0, atof(argv[2]));
      }
    else if (argc == 4)
      {
      contours->SetValue(0, atof(argv[2]));
      contours->SetValue(1, atof(argv[3]));
      }
    else if (argc == 5)
      {
      contours->GenerateValues(atoi(argv[2]),
                               atof(argv[3]),
                               atof(argv[4]));
      }
    }
  else
    {
    vtkSmartPointer<vtkPlaneSource> plane =
      vtkSmartPointer<vtkPlaneSource>::New();
    plane->SetXResolution(10);
    plane->SetYResolution(10);
    plane->Update();
 
    vtkSmartPointer<vtkDoubleArray> randomScalars =
      vtkSmartPointer<vtkDoubleArray>::New();
    randomScalars->SetNumberOfComponents(1);
    randomScalars->SetName("Isovalues");
    for (int i = 0; i < plane->GetOutput()->GetNumberOfPoints(); i++)
      {
      randomScalars->InsertNextTuple1(vtkMath::Random(-100.0, 100.0));
      }
    plane->GetOutput()->GetPointData()->SetScalars(randomScalars);
    polyData = plane->GetOutput();
    contours->SetInputConnection(plane->GetOutputPort());
    contours->GenerateValues(5, -100, 100);
    pointThreshold = 0;
  }    
 
  // Connect the segments of the conours into polylines
  vtkSmartPointer<vtkStripper> contourStripper =
    vtkSmartPointer<vtkStripper>::New();
  contourStripper->SetInputConnection(contours->GetOutputPort());
  contourStripper->Update();
 
  int numberOfContourLines = contourStripper->GetOutput()->GetNumberOfLines();
 
  std::cout << "There are "
            << numberOfContourLines << " contours lines."
            << std::endl;
 
  vtkPoints *points     =
    contourStripper->GetOutput()->GetPoints();
  vtkCellArray *cells   =
    contourStripper->GetOutput()->GetLines();
  vtkDataArray *scalars =
    contourStripper->GetOutput()->GetPointData()->GetScalars();
 
  // Create a polydata that contains point locations for the contour
  // line labels
  vtkSmartPointer<vtkPolyData> labelPolyData =
    vtkSmartPointer<vtkPolyData>::New();
  vtkSmartPointer<vtkPoints> labelPoints =
    vtkSmartPointer<vtkPoints>::New();
  vtkSmartPointer<vtkDoubleArray> labelScalars =
    vtkSmartPointer<vtkDoubleArray>::New();
  labelScalars->SetNumberOfComponents(1);
  labelScalars->SetName("Isovalues");
 
  vtkIdType *indices;
  vtkIdType numberOfPoints;
  unsigned int lineCount = 0;
  for (cells->InitTraversal();
       cells->GetNextCell(numberOfPoints, indices);
       lineCount++)
    {
    if (numberOfPoints < pointThreshold)
      {
      continue;
      }
    std::cout << "Line " << lineCount << ": " << std::endl;
 
    // Compute the point id to hold the label
    // Mid point or a random point
    vtkIdType midPointId = indices[numberOfPoints / 2];
    midPointId =
      indices[static_cast<vtkIdType>(vtkMath::Random(0, numberOfPoints))];
 
    double midPoint[3];
    points->GetPoint(midPointId, midPoint);
    std::cout << "\tmidPoint is " << midPointId << " with coordinate "
              << "("
              << midPoint[0] << ", "
              << midPoint[1] << ", "
              << midPoint[2] << ")"
              << " and value " << scalars->GetTuple1(midPointId)
              << std::endl;
    labelPoints->InsertNextPoint(midPoint);
    labelScalars->InsertNextTuple1(scalars->GetTuple1(midPointId));
    }
  labelPolyData->SetPoints(labelPoints);
  labelPolyData->GetPointData()->SetScalars(labelScalars);
 
  vtkSmartPointer<vtkPolyDataMapper> contourMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  contourMapper->SetInputConnection(contourStripper->GetOutputPort());
  contourMapper->ScalarVisibilityOff();
 
  vtkSmartPointer<vtkActor> isolines =
    vtkSmartPointer<vtkActor>::New();
  isolines->SetMapper(contourMapper);
 
  vtkSmartPointer<vtkLookupTable> surfaceLUT =
    vtkSmartPointer<vtkLookupTable>::New();
  surfaceLUT->SetRange(
    polyData->GetPointData()->GetScalars()->GetRange());
  surfaceLUT->Build();
 
  vtkSmartPointer<vtkPolyDataMapper> surfaceMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  surfaceMapper->SetInput(polyData);
#else
  surfaceMapper->SetInputData(polyData);
#endif
  surfaceMapper->ScalarVisibilityOn();
  surfaceMapper->SetScalarRange(
    polyData->GetPointData()->GetScalars()->GetRange());
  surfaceMapper->SetLookupTable(surfaceLUT);
 
  vtkSmartPointer<vtkActor> surface =
    vtkSmartPointer<vtkActor>::New();
  surface->SetMapper(surfaceMapper);
 
  // The labeled data mapper will place labels at the points
  vtkSmartPointer<vtkLabeledDataMapper> labelMapper =
    vtkSmartPointer<vtkLabeledDataMapper>::New();
  labelMapper->SetFieldDataName("Isovalues");
#if VTK_MAJOR_VERSION <= 5
  labelMapper->SetInput(labelPolyData);
#else
  labelMapper->SetInputData(labelPolyData);
#endif
  labelMapper->SetLabelModeToLabelScalars();
  labelMapper->SetLabelFormat("%6.2f");
 
  vtkSmartPointer<vtkActor2D> isolabels =
    vtkSmartPointer<vtkActor2D>::New();
  isolabels->SetMapper(labelMapper);
 
  // Create a renderer and render window
  vtkSmartPointer<vtkRenderer> renderer = 
      vtkSmartPointer<vtkRenderer>::New();
 
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
      vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
 
  // Create an interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
      vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
 
  // Add the actors to the scene
  renderer->AddActor(isolines);
  renderer->AddActor(isolabels);
//  renderer->AddActor(surface);
 
  // Render the scene (lights and cameras are created automatically)
  renderWindow->Render();
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}