# Vtkglut

VTKExamples/Cxx//vtkglut

### Description

This page illustrates how to use the new method '''vtkRenderWindow::InitializeFromCurrentContext()''' to associate a vtkRenderWindow instance to an existing window and activated OpenGL context.

By using this method, VTK do not create the rendering container nor the OpenGL context but inherit from the one created somewhere else. This allows a vtkRenderWindow and thus VTK to be easily embedded in an existing graphical application.

The following code shows how to embed a VTK RenderWindow in a very simple GLUT based application which shows a vtkCone in rotation.

It has been successfully tested under Linux, Windows & MacOS X.

The interaction part is not shown here but it works as usual, you just need to pass the GLUT events to your VTK interactor.

### Code

vtkglut.cxx

    #ifndef __APPLE_CC__
    #include <GL/glut.h>
    #else
    #include <glut.h>
    #endif
    #include "vtkConeSource.h"
    #include "vtkPolyDataMapper.h"
    #include "vtkRenderWindow.h"
    #include "vtkCamera.h"
    #include "vtkActor.h"
    #include "vtkRenderer.h"
    #include "vtkNew.h"

    vtkNew<vtkRenderer> ren;
    vtkNew<vtkRenderWindow> renWin;

    void Reshape( int width, int height )
    {
      renWin->SetSize( width, height );
    }

    void Draw()
    {
      renWin->Render();
      ren->GetActiveCamera()->Azimuth( 1 );
      glutPostRedisplay();
    }

    int main( int argc, char **argv )
    {
      // GLUT initialization
      glutInit( &argc, argv );
      glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
      glutCreateWindow( "VTK-GLUT Example") ;
      glutReshapeFunc( Reshape );
      glutDisplayFunc( Draw );

      // Creation of a simple VTK pipeline
      vtkNew<vtkConeSource> cone;

      vtkNew<vtkPolyDataMapper> coneMapper;
      coneMapper->SetInputConnection( cone->GetOutputPort() );

      vtkNew<vtkActor> coneActor;
      coneActor->SetMapper( coneMapper.GetPointer() );

      ren->AddActor( coneActor.GetPointer() );
      renWin->AddRenderer( ren.GetPointer() );

      // Here is the trick: we ask the RenderWindow to join the current OpenGL context created by GLUT
      renWin->InitializeFromCurrentContext();

      // Let's start the main GLUT rendering loop
      glutMainLoop();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(vtkglut)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(vtkglut MACOSX_BUNDLE vtkglut.cxx)

    target_link_libraries(vtkglut ${VTK_LIBRARIES})

### Download and Build vtkglut

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

    cd vtkglut/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:

    ./vtkglut

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