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Ubuntu 13.10 C++ OpenGL GLUT - linking issues - undefined reference to `glClearColor'
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Solved c++eclipseopenglubuntufreeglut
A

1

8

I am running Ubuntu 13.10 and trying to compile that portion of sample OpenGL code:

#include "GL/freeglut.h"
#include "GL/gl.h"

/* display function - code from:
     http://fly.cc.fer.hr/~unreal/theredbook/chapter01.html
This is the actual usage of the OpenGL library.
The following code is the same for any platform */
void renderFunction()
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
    glBegin(GL_POLYGON);
        glVertex2f(-0.5, -0.5);
        glVertex2f(-0.5, 0.5);
        glVertex2f(0.5, 0.5);
        glVertex2f(0.5, -0.5);
    glEnd();
    glFlush();
}

/* Main method - main entry point of application
the freeglut library does the window creation work for us,
regardless of the platform. */
int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE);
    glutInitWindowSize(500,500);
    glutInitWindowPosition(100,100);
    glutCreateWindow("OpenGL - First window demo");
    glutDisplayFunc(renderFunction);
    glutMainLoop();
    return 0;
}

I've used Eclipse to build the project, however it fails on linking level:

Building target: opengl_test
Invoking: GCC C++ Linker
g++ -L/usr/lib -L/usr/lib/fglrx -L/usr/lib/x86_64-linux-gnu -L/usr/lib/i386-linux-gnu/mesa -L/usr/lib/x86_64-linux-gnu/mesa -o "opengl_test"  ./src/opengl_test.o   
./src/opengl_test.o: In function `renderFunction()':
/var/www/opengl_test/Debug/../src/opengl_test.cpp:10: undefined reference to `glClearColor'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:11: undefined reference to `glClear'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:12: undefined reference to `glColor3f'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:13: undefined reference to `glOrtho'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:14: undefined reference to `glBegin'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:15: undefined reference to `glVertex2f'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:16: undefined reference to `glVertex2f'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:17: undefined reference to `glVertex2f'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:18: undefined reference to `glVertex2f'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:19: undefined reference to `glEnd'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:20: undefined reference to `glFlush'
./src/opengl_test.o: In function `main':
/var/www/opengl_test/Debug/../src/opengl_test.cpp:28: undefined reference to `glutInit'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:29: undefined reference to `glutInitDisplayMode'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:30: undefined reference to `glutInitWindowSize'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:31: undefined reference to `glutInitWindowPosition'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:32: undefined reference to `glutCreateWindow'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:33: undefined reference to `glutDisplayFunc'
/var/www/opengl_test/Debug/../src/opengl_test.cpp:34: undefined reference to `glutMainLoop'
collect2: error: ld returned 1 exit status
make: *** [opengl_test] Error 1

... so I've tried G++:

g++ -lGL -lglut opengl_test.cpp  -o test

However it gives pretty much the same output as Eclipse one.

I thought that maybe I need symlink necessary libs manually to /usr/lib. I've searched for libs:

$ sudo apt-file search libGL.so
fglrx: /usr/lib/fglrx/libGL.so
fglrx: /usr/lib/fglrx/libGL.so.1
fglrx: /usr/lib/fglrx/libGL.so.1.2
fglrx: /usr/lib32/fglrx/libGL.so.1.2
fglrx-updates: /usr/lib/fglrx/libGL.so
fglrx-updates: /usr/lib/fglrx/libGL.so.1
fglrx-updates: /usr/lib/fglrx/libGL.so.1.2
fglrx-updates: /usr/lib32/fglrx/libGL.so.1.2
libgl1-mesa-dev: /usr/lib/x86_64-linux-gnu/libGL.so
libgl1-mesa-dev: /usr/lib/x86_64-linux-gnu/mesa/libGL.so
libgl1-mesa-glx: /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
libgl1-mesa-glx: /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1.2.0
libgl1-mesa-glx-dbg: /usr/lib/debug/usr/lib/x86_64-linux-gnu/mesa/libGL.so.1.2.0
nvidia-173: /usr/lib/nvidia-173/libGL.so
nvidia-173: /usr/lib/nvidia-173/libGL.so.1
nvidia-173: /usr/lib/nvidia-173/libGL.so.173.14.37
nvidia-173: /usr/lib32/nvidia-173/libGL.so
nvidia-173: /usr/lib32/nvidia-173/libGL.so.1
nvidia-173: /usr/lib32/nvidia-173/libGL.so.173.14.37
nvidia-304: /usr/lib/nvidia-304/libGL.so
nvidia-304: /usr/lib/nvidia-304/libGL.so.1
nvidia-304: /usr/lib/nvidia-304/libGL.so.304.88
nvidia-304: /usr/lib32/nvidia-304/libGL.so
nvidia-304: /usr/lib32/nvidia-304/libGL.so.1
nvidia-304: /usr/lib32/nvidia-304/libGL.so.304.88
nvidia-304-updates: /usr/lib/nvidia-304-updates/libGL.so
nvidia-304-updates: /usr/lib/nvidia-304-updates/libGL.so.1
nvidia-304-updates: /usr/lib/nvidia-304-updates/libGL.so.304.108
nvidia-304-updates: /usr/lib32/nvidia-304-updates/libGL.so
nvidia-304-updates: /usr/lib32/nvidia-304-updates/libGL.so.1
nvidia-304-updates: /usr/lib32/nvidia-304-updates/libGL.so.304.108
nvidia-319: /usr/lib/nvidia-319/libGL.so
nvidia-319: /usr/lib/nvidia-319/libGL.so.1
nvidia-319: /usr/lib/nvidia-319/libGL.so.319.32
nvidia-319: /usr/lib32/nvidia-319/libGL.so
nvidia-319: /usr/lib32/nvidia-319/libGL.so.1
nvidia-319: /usr/lib32/nvidia-319/libGL.so.319.32
nvidia-319-updates: /usr/lib/nvidia-319-updates/libGL.so
nvidia-319-updates: /usr/lib/nvidia-319-updates/libGL.so.1
nvidia-319-updates: /usr/lib/nvidia-319-updates/libGL.so.319.60
nvidia-319-updates: /usr/lib32/nvidia-319-updates/libGL.so
nvidia-319-updates: /usr/lib32/nvidia-319-updates/libGL.so.1
nvidia-319-updates: /usr/lib32/nvidia-319-updates/libGL.so.319.60
primus-libs: /usr/lib/x86_64-linux-gnu/primus/libGL.so.1

and

$ sudo apt-file search libglut.so
freeglut3: /usr/lib/x86_64-linux-gnu/libglut.so.3
freeglut3: /usr/lib/x86_64-linux-gnu/libglut.so.3.9.0
freeglut3-dev: /usr/lib/x86_64-linux-gnu/libglut.so

Made symlinks:

sudo ln -s /usr/lib/fglrx/libGL.so /usr/lib/libGL.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libglut.so /usr/lib/libglut.so

However it still did not help. The same linking issue appeared.

  1. How do I debug that issue?
  2. How do I know which lib to choose and link them to /usr/lib? I chose fglrx, because my GPU drivers are running fglrx.
  3. Do I need each time to link library manually from /usr/lib..../somewhere to /usr/lib?
Ankle answered 20/1, 2014 at 21:40 Comment(1)
It's a shame. Could not find the answer using Google, but found the answer via related panel on Stackoverflow: #15204077 Still need to work out why does Eclipse fail, but that's the Eclipse itself related. – Ankle
Z
15

Try putting your libraries after the source file:

g++ opengl_test.cpp -lGL -lglut

To get Eclipse working you need to change so called "command line pattern". I am not Eclipse user actually, but try to check settings here: C/C++ Build -> Settings -> Cross G++ Linker, or some other Linker-related settings.

Clarification: current ld defaults to link with --as-needed flag. In this mode before linking any library ld checks that some symbols from this library needed somewhere. ld perform this checks in order, so if you link something before your source file this library gets excluded. This behaviour can be disabled using -Wl,--no-as-needed gcc flag.

From man ld:

--as-needed
--no-as-needed
    This option affects ELF DT_NEEDED tags for dynamic  libraries  men-
    tioned on the command line after the --as-needed option.  Normally,
    the linker will add a DT_NEEDED tag for each dynamic     library  men-
    tioned  on  the  command line, regardless of whether the library is
    actually needed.  --as-needed causes     DT_NEEDED  tags  to  only  be
    emitted for libraries that satisfy some symbol reference from regu-
    lar objects which is undefined at the point that  the  library  was
    linked.  --no-as-needed restores the default behaviour.
Zamora answered 20/1, 2014 at 21:51 Comment(5)
Yes, that did it well. See my above comment, at the same time found an answer. Anyway Thanks. – Ankle
@NeverEndingQueue Trying to find solution for Eclipse. Check my edit please. – Zamora
I've managed to make a build using Eclipse, but I had to manualy add libraries: GL glut I thought I can add just /usr/lib and all lib directly here in that folder would be available. When I add that path Eclipse tries to build with -L/usr/lib but it gives same linker issues. – Ankle
Try to pass -Wl,--no-as-needed flag please. – Zamora
Thanks for explanation of --as-needed behaviour. My Eclipse issues was that I did not includ the libraries separately. When I've specified them, Eclipse created correct command order so, --no-as-needed flag it's not necessary right now. I've just thought that if I pass -L flag it will grab all the necessary libs. The -L it's just dir path where shoud linker search and you still need to use -l flag to give the libraries. Anyway thanks for proactivity. – Ankle

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