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AlphaFrequency

vtk-examples/Cxx/Visualization/AlphaFrequency


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Code

AlphaFrequency.cxx

//
// Create bar charts of frequency of letters.
//
#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkLinearExtrusionFilter.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkVectorText.h>

#include <vector>

int main(int argc, char* argv[])
{
  vtkNew<vtkNamedColors> colors;

  std::vector<vtkSmartPointer<vtkVectorText>> letters;
  std::vector<vtkSmartPointer<vtkLinearExtrusionFilter>> extrude;
  std::vector<vtkSmartPointer<vtkPolyDataMapper>> mappers;
  std::vector<vtkSmartPointer<vtkActor>> actors;

  char filename[512];
  char text[2];
  static char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  int i, j, freq[26], maxFreq;
  float x, y;
  FILE* fPtr;
  int c;

  //
  // count the letters
  //
  if ((argc == 1) || ((argc == 2) && !(strcmp("-S", argv[1]))))
  {
    cerr << "Please provide filename: " << argv[0] << " filename\n";
    strcpy(filename, "./Makefile");
    cerr << "Using the file " << filename << " as input\n";
  }
  else
  {
    strcpy(filename, argv[1]);
  }

  if ((fPtr = fopen(filename, "r")) == NULL)
  {
    cerr << "Cannot open file: " << filename << "\n";
    exit(1);
  }

  for (i = 0; i < 26; i++) freq[i] = 0;
  while ((c = fgetc(fPtr)) != EOF)
  {
    if (isalpha(c))
    {
      c = tolower(c);
      freq[c - 97]++;
    }
  }

  for (maxFreq = 0, i = 0; i < 26; i++)
    if (freq[i] > maxFreq)
      maxFreq = freq[i];
  //
  // graphics stuff
  //
  vtkNew<vtkRenderer> ren;
  vtkNew<vtkRenderWindow> renWin;
  renWin->AddRenderer(ren);
  vtkNew<vtkRenderWindowInteractor> iren;
  iren->SetRenderWindow(renWin);
  //
  // Setup letters
  //
  text[1] = '\0';
  for (i = 0; i < 26; i++)
  {
    text[0] = alphabet[i];
    letters.push_back(vtkSmartPointer<vtkVectorText>::New());
    letters[i]->SetText(text);

    extrude.push_back(vtkSmartPointer<vtkLinearExtrusionFilter>::New());
    extrude[i]->SetInputConnection(letters[i]->GetOutputPort());
    extrude[i]->SetExtrusionType(VTK_VECTOR_EXTRUSION);
    extrude[i]->SetVector(0, 0, 1.0);
    extrude[i]->SetScaleFactor((double)freq[i] / maxFreq * 2.50);

    mappers.push_back(vtkSmartPointer<vtkPolyDataMapper>::New());
    mappers[i]->SetInputConnection(extrude[i]->GetOutputPort());
    mappers[i]->ScalarVisibilityOff();

    actors.push_back(vtkSmartPointer<vtkActor>::New());
    actors[i]->SetMapper(mappers[i]);
    actors[i]->GetProperty()->SetColor(colors->GetColor3d("Peacock").GetData());
    if (freq[i] <= 0)
    {
      actors[i]->VisibilityOff();
    }
    ren->AddActor(actors[i]);
  }
  //
  // Position actors
  //
  for (y = 0.0, j = 0; j < 2; j++, y += (-3.0))
  {
    for (x = 0.0, i = 0; i < 13; i++, x += 1.5)
    {
      actors[j * 13 + i]->SetPosition(x, y, 0.0);
    }
  }

  ren->ResetCamera();
  ren->SetBackground(colors->GetColor3d("Silver").GetData());
  ren->GetActiveCamera()->Elevation(30.0);
  ren->GetActiveCamera()->Azimuth(-30.0);
  ren->GetActiveCamera()->Dolly(1.25);
  ren->ResetCameraClippingRange();

  renWin->SetSize(640, 480);
  renWin->SetWindowName("AlphaFrequency");

  // interact with data
  renWin->Render();
  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(AlphaFrequency)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkFiltersModeling
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping AlphaFrequency: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(AlphaFrequency MACOSX_BUNDLE AlphaFrequency.cxx )
  target_link_libraries(AlphaFrequency PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(AlphaFrequency MACOSX_BUNDLE AlphaFrequency.cxx )
  target_link_libraries(AlphaFrequency PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS AlphaFrequency
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build AlphaFrequency

Click here to download AlphaFrequency and its CMakeLists.txt file. Once the tarball AlphaFrequency.tar has been downloaded and extracted,

cd AlphaFrequency/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./AlphaFrequency

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.