title: Building FLTK Project in Eclipse
body: <p>I am having trouble getting set up with FLTK in Eclipse.  I am trying to create an OpenGL window with the following code (which I found <a href="http://www.gidforums.com/t-10971.html" rel="nofollow noreferrer">here</a>):</p>
  
  <pre><code>#include &lt;FL/Fl.H&gt;
  #include &lt;FL/Fl_Gl_Window.H&gt;
  #include &lt;FL/gl.h&gt;
  
  //
  // Simple resizable 2D GL  window
  // erco 10/08/05
  //
  class MyGlWindow : public Fl_Gl_Window {
      // DRAW METHOD
      //       OpenGL window: (w,h) is upper right, (-w,-h) is lower left, (0,0) is center
      //
      void draw() {
          // First time? init viewport, etc.
          if (!valid()) {
              valid(1);
              glLoadIdentity();
              glViewport(0,0,w(),h());
              glOrtho(-w(),w(),-h(),h(),-1,1);
          }
          //  Clear screen
          glClear(GL_COLOR_BUFFER_BIT);
          //  Draw white 'X'
          glColor3f(1.0, 1.0, 1.0);
          glBegin(GL_LINE_STRIP); glVertex2f(w(), h()); glVertex2f(-w(),-h()); glEnd();
          glBegin(GL_LINE_STRIP); glVertex2f(w(),-h()); glVertex2f(-w(), h()); glEnd();
      }
      // HANDLE WINDOW RESIZING
      //    If window reshaped, need to readjust viewport/ortho
      //
      void resize(int X,int Y,int W,int H) {
          Fl_Gl_Window::resize(X,Y,W,H);
          glLoadIdentity();
          glViewport(0,0,W,H);
          glOrtho(-W,W,-H,H,-1,1);
          redraw();
      }
  public:
      // CONSTRUCTOR
      MyGlWindow(int X,int Y,int W,int H,const char*L=0) : Fl_Gl_Window(X,Y,W,H,L) {
      }
  };
  // MAIN
  int main() {
       Fl_Window win( 500,  300);
       MyGlWindow mygl(10, 10, win.w()-20, win.h()-20);
       win.resizable(mygl);
       win.show();
       return(Fl::run());
  }
  </code></pre>
  
  <p>Here are the commands being issued:</p>
  
  <pre><code>make -k all 
  Building file: ../main.cpp
  Invoking: GCC C++ Compiler
  g++ -I/usr/include/FL -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp"
  Finished building: ../main.cpp
  
  Building target: Experiment01
  Invoking: GCC C++ Linker
  g++ -L/usr/lib -o"Experiment01"  ./main.o   -lGL -lfltk
  </code></pre>
  
  <p>And here are the errors:</p>
  
  <pre><code>/usr/include/FL/Fl_Gl_Window.H undefined reference to `Fl_Gl_Window::init()'
  /usr/include/FL/Fl_Gl_Window.H undefined reference to `vtable for Fl_Gl_Window'
  undefined reference to `Fl_Gl_Window::~Fl_Gl_Window()'
  undefined reference to `Fl_Gl_Window::resize(int, int, int, int)'
  </code></pre>
  
  <p>What else do I need to link?  I've tried -llibfltk.so -llibfltk_gl.so, etc., but it always says that it cannot find the specified library.</p>