AppendFilter

VTKEx/Cxx/Filtering/AppendFilter

Description

This example loads points into a polydata and an unstructured grid then combines them.

The example should be extended to show cells being combined as well.

Other languages

See (Python)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

AppendFilter.cxx

#include <vtkSmartPointer.h>
#include <vtkAppendFilter.h>

#include <vtkActor.h>
#include <vtkDataSetMapper.h>
#include <vtkPointSource.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkUnstructuredGrid.h>
#include <vtkNamedColors.h>

int main(int, char *[])
{
  // Create 5 points (vtkPolyData)
  vtkSmartPointer<vtkPointSource> pointSource =
    vtkSmartPointer<vtkPointSource>::New();
  pointSource->SetNumberOfPoints(5);
  pointSource->Update();

  vtkSmartPointer<vtkPolyData> polydata = pointSource->GetOutput();

  std::cout << "There are " << polydata->GetNumberOfPoints()
            << " points in the polydata." << std::endl;

  // Create 2 points in a vtkUnstructuredGrid

  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(0,0,0);
  points->InsertNextPoint(0,0,1);

  vtkSmartPointer<vtkUnstructuredGrid> ug =
    vtkSmartPointer<vtkUnstructuredGrid>::New();
  ug->SetPoints(points);

  std::cout << "There are " << ug->GetNumberOfPoints()
            << " points in the unstructured grid." << std::endl;

  // Combine the two data sets
  vtkSmartPointer<vtkAppendFilter> appendFilter =
    vtkSmartPointer<vtkAppendFilter>::New();
  appendFilter->AddInputData(polydata);
  appendFilter->AddInputData(ug);
  appendFilter->Update();

  vtkSmartPointer<vtkUnstructuredGrid> combined =
    appendFilter->GetOutput();
  std::cout << "There are " << combined->GetNumberOfPoints()
            << " points combined." << std::endl;

  // Create a mapper and actor
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  mapper->SetInputConnection(appendFilter->GetOutputPort());

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  actor->GetProperty()->SetPointSize(5);

  // Create a renderer, render window, 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);

  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(AppendFilter)

find_package(VTK COMPONENTS 
  vtkvtkCommonColor
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkFiltersCore
  vtkvtkFiltersSources
  vtkvtkInteractionStyle
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping AppendFilter: ${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(AppendFilter MACOSX_BUNDLE AppendFilter.cxx )
  target_link_libraries(AppendFilter PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(AppendFilter MACOSX_BUNDLE AppendFilter.cxx )
  target_link_libraries(AppendFilter PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS AppendFilter
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build AppendFilter

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

cd AppendFilter/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:

./AppendFilter

WINDOWS USERS

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