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Follower

vtk-examples/Cxx/Visualization/Follower


Description

The text is a 3D actor and is placed in 3D space, but stays right side up and facing the camera, while the cube does not.

Other languages

See (Java)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

Follower.cxx

#include <vtkActor.h>
#include <vtkCubeSource.h>
#include <vtkFollower.h>
#include <vtkInteractorStyle.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkVectorText.h>

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

  // Create some text
  vtkNew<vtkVectorText> textSource;
  textSource->SetText("Hello");

  // Create a mapper
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(textSource->GetOutputPort());

  // Create a subclass of vtkActor: a vtkFollower that remains facing the camera
  vtkNew<vtkFollower> follower;
  follower->SetMapper(mapper);
  follower->GetProperty()->SetColor(colors->GetColor3d("Gold").GetData());

  // Create a transparent cube that does not move around to face the camera
  vtkNew<vtkCubeSource> cubeSource;
  vtkNew<vtkPolyDataMapper> cubeMapper;
  cubeMapper->SetInputConnection(cubeSource->GetOutputPort());
  vtkNew<vtkActor> cubeActor;
  cubeActor->SetMapper(cubeMapper);
  cubeActor->GetProperty()->SetColor(
      colors->GetColor3d("MidnightBlue").GetData());
  cubeActor->GetProperty()->SetOpacity(0.3);

  // Create a renderer, render window, and interactor
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("Follower");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  dynamic_cast<vtkInteractorStyle*>(
      renderWindowInteractor->GetInteractorStyle())
      ->AutoAdjustCameraClippingRangeOn();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actor to the scene
  renderer->AddActor(follower);
  renderer->AddActor(cubeActor);
  renderer->SetBackground(colors->GetColor3d("LightSlateGray").GetData());
  follower->SetCamera(renderer->GetActiveCamera());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Follower)

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

if (NOT VTK_FOUND)
  message("Skipping Follower: ${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(Follower MACOSX_BUNDLE Follower.cxx )
  target_link_libraries(Follower PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Follower MACOSX_BUNDLE Follower.cxx )
  target_link_libraries(Follower PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Follower
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build Follower

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

cd Follower/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:

./Follower

WINDOWS USERS

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