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SpotLights

vtk-examples/Cxx/Lighting/SpotLights


Description

This example places two vtkLight's with PositionalOn().

Cite

This example was inspired by Oliver Natt's question (and python script) on the VTK Users mailing list.

Question

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

Code

SpotLights.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkLight.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPlaneSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

int main(int, char*[])
{
  // create a rendering window and renderer
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(640, 480);
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("SpotLights");

  // create a renderwindowinteractor
  vtkNew<vtkRenderWindowInteractor> iren;
  iren->SetRenderWindow(renderWindow);

  // create a plane and add it to the renderer
  vtkNew<vtkPlaneSource> source;
  source->SetOrigin(-5.0, 0.0, 5.0);
  source->SetPoint1(5.0, 0.0, 5.0);
  source->SetPoint2(-5.0, 0.0, -5.0);
  source->SetResolution(100, 100);
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(source->GetOutputPort());

  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  renderer->AddActor(actor);

  // set camera view
  renderer->ResetCamera();
  renderer->GetActiveCamera()->Azimuth(40.0);
  renderer->GetActiveCamera()->Elevation(30.0);

  // create a green light
  vtkNew<vtkLight> greenLight;
  greenLight->PositionalOn();
  greenLight->SetPosition(-4.0, 4.0, -1.0);
  greenLight->SetColor(colors->GetColor3d("Lawn_green").GetData());
  greenLight->SetIntensity(0.5);

  // create a pink light
  vtkNew<vtkLight> pinkLight;
  pinkLight->PositionalOn();
  pinkLight->SetPosition(4.0, 5.0, 1.0);
  pinkLight->SetColor(colors->GetColor3d("DeepPink").GetData());
  pinkLight->SetIntensity(0.6);

  // add lights to the renderer
  renderer->AddLight(pinkLight);
  renderer->AddLight(greenLight);

  // define a background for better visibility
  renderer->SetBackground(colors->GetColor3d("RoyalBlue").GetData());
  renderer->SetBackground2(colors->GetColor3d("SkyBlue").GetData());
  renderer->GradientBackgroundOn();

  // enable interactor
  iren->Initialize();
  renderWindow->Render();
  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(SpotLights)

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

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

Download and Build SpotLights

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

cd SpotLights/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:

./SpotLights

WINDOWS USERS

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