# TransformActor

VTKExamples/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.

### 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
      vtkCommonCore
      vtkCommonDataModel
      vtkCommonTransforms
      vtkFiltersSources
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 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.