LegendScaleActor

Description¶

The vtkLegendScaleActor object is used to annotate the render window. Its basic goal is to provide an indication of the scale of the scene. Four axes surrounding the render window indicate (in a variety of ways) the scale of what the camera is viewing. An option also exists for displaying a scale legend.

The axes can be programmed either to display distance scales or x-y coordinate values. By default, the scales display a distance. However, if you know that the view is down the z-axis, the scales can be programmed to display x-y coordinate values.

Other languages

See (PythonicAPI), (Java)

Question

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

Code¶

LegendScaleActor.cxx

#include <vtkActor.h>
#include <vtkAxisActor2D.h>
#include <vtkLegendScaleActor.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkParametricEnneper.h>
#include <vtkParametricFunctionSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkProperty2D.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

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

  // The source will be a parametric function.
  vtkNew<vtkParametricEnneper> src;
  vtkNew<vtkParametricFunctionSource> fnSrc;
  fnSrc->SetParametricFunction(src);

  // Create a mapper and actor.
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(fnSrc->GetOutputPort());
  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("SandyBrown").GetData());

  // Create a renderer, render window, and interactor.
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("LegendScaleActor");
  renderWindow->SetSize(600, 600);

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

  vtkNew<vtkLegendScaleActor> legendScaleActor;

  auto axesProp = legendScaleActor->GetAxesProperty();

  axesProp->SetColor(colors->GetColor3d("Red").GetData());

  legendScaleActor->GetTopAxis()->SetProperty(axesProp);
  legendScaleActor->GetLeftAxis()->SetProperty(axesProp);
  legendScaleActor->GetBottomAxis()->SetProperty(axesProp);

  // Add the actor to the scene.
  renderer->AddActor(actor);
  renderer->AddActor(legendScaleActor);

  renderer->SetBackground(colors->GetColor3d("MidnightBlue").GetData());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(LegendScaleActor)

find_package(VTK COMPONENTS 
  CommonColor
  CommonComputationalGeometry
  CommonCore
  FiltersSources
  InteractionStyle
  RenderingAnnotation
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "LegendScaleActor: 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(LegendScaleActor MACOSX_BUNDLE LegendScaleActor.cxx )
  target_link_libraries(LegendScaleActor PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS LegendScaleActor
  MODULES ${VTK_LIBRARIES}
)

Download and Build LegendScaleActor¶

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

cd LegendScaleActor/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:

./LegendScaleActor

WINDOWS USERS

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