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 question about this example, please use the VTK Discourse Forum

Code¶

TransformActor.cxx

#include <vtkActor.h>
#include <vtkConeSource.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 <vtkTransform.h>

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

  // Create a cone
  vtkNew<vtkConeSource> coneSource1;
  coneSource1->Update();

  vtkNew<vtkConeSource> coneSource2;
  coneSource2->Update();

  vtkNew<vtkPolyDataMapper> mapper1;
  mapper1->SetInputConnection(coneSource1->GetOutputPort());
  vtkNew<vtkActor> actor1;
  actor1->SetMapper(mapper1);
  actor1->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());

  // Create a second, transformed cone
  vtkNew<vtkPolyDataMapper> mapper2;
  mapper2->SetInputConnection(coneSource2->GetOutputPort());
  vtkNew<vtkActor> actor2;
  actor2->SetMapper(mapper2);
  actor2->GetProperty()->SetColor(colors->GetColor3d("Cornsilk").GetData());

  vtkNew<vtkTransform> transform;
  transform->PostMultiply(); // this is the key line
  transform->RotateZ(90.0);

  actor2->SetUserTransform(transform);

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

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actor to the scene
  renderer->AddActor(actor1);
  renderer->AddActor(actor2);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(TransformActor)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  CommonTransforms
  FiltersSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "TransformActor: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
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}
)

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.