Circle

VTKExamples/Cxx/GeometricObjects/Circle


Description

A circle is simply the limiting case of a regular polygon. We use vtkRegularPolygonSource with a large number of Sides to approximate a circle.

Other Languages

See (Python), (Java)

Code

Circle.cxx

// Classes specific to this example
#include <vtkRegularPolygonSource.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
// Generic VTK pipeline elements
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
// Auxiliary class
#include <vtkSmartPointer.h>

int main(int, char *[])
{
  // Create a circle
  vtkSmartPointer<vtkRegularPolygonSource> polygonSource =
    vtkSmartPointer<vtkRegularPolygonSource>::New();

  //polygonSource->GeneratePolygonOff(); // Uncomment this line to generate only the outline of the circle
  polygonSource->SetNumberOfSides(50);
  polygonSource->SetRadius(5);
  polygonSource->SetCenter(0, 0, 0);

  // Visualize
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(polygonSource->GetOutputPort());;

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(actor);
  renderer->SetBackground(.3,.3,.5); // Background color purple

  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Circle)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping Circle: ${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(Circle MACOSX_BUNDLE Circle.cxx )
  target_link_libraries(Circle PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Circle MACOSX_BUNDLE Circle.cxx )
  target_link_libraries(Circle PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Circle
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build Circle

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

cd Circle/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:

./Circle

WINDOWS USERS

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