SphereWidget2

VTKExamples/Cxx/Widgets/SphereWidget2


Description

The spherical coordinates of the widget's handle match the coordinates that it displays in the window. The world coordinates of the handle are also shown.

Question

If you have a simple question about this example contact us at VTKExamplesProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

SphereWidget2.cxx

#include <vtkCommand.h>
#include <vtkMath.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkSphere.h>
#include <vtkSphereRepresentation.h>
#include <vtkSphereWidget2.h>

// Callback that displays the sphere widget's spherical handle postion
// in both sphercial (relative to the widget's center) and cartesian global coordinates
class vtkSphereCallback : public vtkCommand
{
public:
  static vtkSphereCallback *New()
  {
    return new vtkSphereCallback;
  }

  virtual void Execute(vtkObject *caller, unsigned long, void*)
  {
    vtkSphereWidget2 *sphereWidget =
      reinterpret_cast<vtkSphereWidget2*>(caller);

    double center[3], handlePosition[3];
    vtkSphereRepresentation* sphereRepresentation =
      dynamic_cast<vtkSphereRepresentation*>( sphereWidget->GetRepresentation() );
    sphereRepresentation->GetHandlePosition( handlePosition );
    sphereRepresentation->GetSphere( this->Sphere );

    this->Sphere->GetCenter( center );

    double radius = sqrt( static_cast<double>(vtkMath::Distance2BetweenPoints( center, handlePosition ) ) );
    radius = (radius <= 0.0 ? 1.0 : radius );
    double theta = vtkMath::DegreesFromRadians( atan2( ( handlePosition[1] - center[1] ), ( handlePosition[0] - center[0] ) ) );
    double phi   = vtkMath::DegreesFromRadians( acos( ( handlePosition[2] - center[2] ) / radius ) );

    std::cout << "r, theta, phi: ("
              << std::setprecision(3)
              << radius << ", " << theta << ", " << phi << ") "
              << "x, y, z: ("
              << handlePosition[0] << ", "
              << handlePosition[1] << ", "
              << handlePosition[2] << ") "
              << std::endl;
  }

  vtkSphereCallback(){ this->Sphere = vtkSphere::New(); }
  ~vtkSphereCallback(){ this->Sphere->Delete(); }

  vtkSphere* Sphere;
};

int main( int, char *[] )
{
  // Create a renderer and a render window
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  // Create an interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Create a sphere widget
  vtkSmartPointer<vtkSphereWidget2> sphereWidget =
    vtkSmartPointer<vtkSphereWidget2>::New();
  sphereWidget->SetInteractor(renderWindowInteractor);
  sphereWidget->CreateDefaultRepresentation();

  vtkSphereRepresentation* sphereRepresentation =
    dynamic_cast<vtkSphereRepresentation*>( sphereWidget->GetRepresentation() );
  sphereRepresentation->HandleVisibilityOn();

  vtkSmartPointer<vtkSphereCallback> sphereCallback =
    vtkSmartPointer<vtkSphereCallback>::New();

  sphereWidget->AddObserver( vtkCommand::InteractionEvent, sphereCallback );

  renderWindow->Render();

  renderWindowInteractor->Initialize();
  renderWindow->Render();
  sphereWidget->On();

  // Begin mouse interaction
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(SphereWidget2)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkInteractionStyle
  vtkInteractionWidgets
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping SphereWidget2: ${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(SphereWidget2 MACOSX_BUNDLE SphereWidget2.cxx )
  target_link_libraries(SphereWidget2 PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(SphereWidget2 MACOSX_BUNDLE SphereWidget2.cxx )
  target_link_libraries(SphereWidget2 PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS SphereWidget2
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build SphereWidget2

Click here to download SphereWidget2 and its CMakeLists.txt file. Once the tarball SphereWidget2.tar has been downloaded and extracted,

cd SphereWidget2/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:

./SphereWidget2

WINDOWS USERS

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