title: CMake could not find OpenGL in Ubuntu
body: <p>I want to install VTK in Ubuntu. CMake sends me this error :</p>
  
  <blockquote>
    <p>CMake Error at
    /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:108
    (message):   Could NOT find OpenGL (missing: OPENGL_gl_LIBRARY
    OPENGL_INCLUDE_DIR) Call Stack (most recent call first):<br>
    /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:315
    (_FPHSA_FAILURE_MESSAGE)<br>
    /usr/share/cmake-2.8/Modules/FindOpenGL.cmake:161
    (FIND_PACKAGE_HANDLE_STANDARD_ARGS)<br>
    Rendering/OpenGL/CMakeLists.txt:196 (find_package)</p>
    
    <p>CMake Error: The following variables are used in this project, but
    they are set to NOTFOUND. Please set them or make sure they are set
    and tested correctly in the CMake files: OPENGL_INCLUDE_DIR (ADVANCED)
    used as include directory in directory
    /home/pilou/Documents/src/VTK-6.2.0/Geovis/Core</p>
  </blockquote>
  
  <p>I have hence installed freeglut3 and build-essential (as I have seen on Internet). But nothing has changed.</p>
  
  <p>How could I find opengl to write my own link to CMake? What else could I do to install VTK? </p>