TransformActor

VTKEx/Cxx/Visualization/TransformActor

Description

This examples demonstrates how to transform an actor. This is different than using vtkTransformPolyDataFilter in that it doesn't actually transform the data (you can't access the transformed coordinates) - it is all done on the video card.

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

TransformActor.cxx

#include <vtkSmartPointer.h>
#include <vtkConeSource.h>
#include <vtkTransform.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

int main(int, char *[])
{
  // Create a cone
  vtkSmartPointer<vtkConeSource> coneSource1 = 
    vtkSmartPointer<vtkConeSource>::New();
  coneSource1->Update();

  vtkSmartPointer<vtkConeSource> coneSource2 = 
    vtkSmartPointer<vtkConeSource>::New();
  coneSource2->Update();

  vtkSmartPointer<vtkPolyDataMapper> mapper1 = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper1->SetInputConnection(coneSource1->GetOutputPort());
  vtkSmartPointer<vtkActor> actor1 = 
    vtkSmartPointer<vtkActor>::New();
  actor1->SetMapper(mapper1);

  // Create a second, transformed cone
  vtkSmartPointer<vtkPolyDataMapper> mapper2 = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper2->SetInputConnection(coneSource2->GetOutputPort());
  vtkSmartPointer<vtkActor> actor2 = 
    vtkSmartPointer<vtkActor>::New();
  actor2->SetMapper(mapper2);

  vtkSmartPointer<vtkTransform> transform = 
    vtkSmartPointer<vtkTransform>::New();
  transform->PostMultiply(); //this is the key line
  transform->RotateZ(90.0);

  actor2->SetUserTransform(transform);

  // 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(actor1);
  renderer->AddActor(actor2);
  renderer->SetBackground(1,1,1); // Background color white

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(TransformActor)

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

Download and Build TransformActor

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

cd TransformActor/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:

./TransformActor

WINDOWS USERS

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