Help needed regarding opengl

eerpini · 06-02-2007, 02:18 PM

i have openGL installed on my FC6 system , i have the header files installed in the standard /usr/include/GL directory , but when i run programs , the gcc compiler does not reecognise the functions which are defined in these header files

the header files i have included are :
#include<GL/glut.h>
#include<GL/gl.h>
#include<GL/glx.h>
#include<GL/glu.h>

i have also tried setting the LD_LIBRARY_PATH variable but of no use , the problem still persists after doin tat !
please help , .
thanks in advance !

raskin · 06-02-2007, 02:33 PM

You should at least quote all error messages from gcc that make you think it doesn't recognize your libraries.

hondo · 06-02-2007, 02:42 PM

If you manally installed the header files into this location and if this location is standard location for libraries, then you should execute the "ldconfig" command and it should work.

eerpini · 06-02-2007, 11:26 PM

these were the errors shown ,
/tmp/ccOpyBLn.o: In function `Transform':
sam.c

.text+0x49): undefined reference to `glViewport'
sam.c

.text+0x55): undefined reference to `glMatrixMode'
sam.c

.text+0x5a): undefined reference to `glLoadIdentity'
sam.c

.text+0x86): undefined reference to `gluPerspective'
sam.c

.text+0x92): undefined reference to `glMatrixMode'

there is no use even when i run the ldconfig command , can u suggest anything else?

eerpini · 06-02-2007, 11:27 PM

this is the other set of errors , i did not postthem above due to lack of space !

/tmp/ccOpyBLn.o: In function `main':
sam.c

.text+0x118): undefined reference to `glutInit'
sam.c

.text+0x124): undefined reference to `glutInitDisplayMode'
sam.c

.text+0x138): undefined reference to `glutInitWindowSize'
sam.c

.text+0x14c): undefined reference to `glutInitWindowPosition'
sam.c

.text+0x158): undefined reference to `glutCreateWindow'
sam.c

.text+0x17f): undefined reference to `glutDisplayFunc'
sam.c

.text+0x184): undefined reference to `glutMainLoop'
collect2: ld returned 1 exit status

raskin · 06-03-2007, 12:08 AM

What -l flags do you specify? -lGL -lGLU , what else?

eerpini · 06-04-2007, 12:04 AM

i did not understand , do we have to give some flags , i mean i just gave the command :
# gcc sam.c,
and then gcc showed the errors i have mentioned above !
please explain !

raskin · 06-04-2007, 12:08 AM

Open Graphics Library is an external package (with respect to glibc, gcc, and all core GNU/Linux system). So gcc will never know it should be used in any quality unless you specify it. It installs its header where gcc looks for them by default, but no libraries are linked in unless they are specified or it is libc. So specify '-lGL -lGLU ' to let gcc know you want it to use libGL.so and linGLU.so .

eerpini · 06-05-2007, 12:20 AM

thanks, it works i gaev the following command, ..

# gcc -lGL -lGLU -lglut sam.c

it worked and gave the output( that is a a.out file was created) , but when i run the output it gives the following error
# ./a.out
./a.out: error while loading shared libraries: libglut.so.3: cannot open shared object file: No such file or directory

now what does this mean , the compiler is able to find the libraries but not machine ??

please help me !

raskin · 06-05-2007, 03:07 AM

Run ldconfig as root.

eerpini · 06-06-2007, 12:15 AM

ya thanks a lot , now i am able to compile and run the code , ........

but is there anyway i could bypass the flags , ....
is it necessary that i give the flags everytime ?

is there no single step solution , so that the programs compile
with just the commmand
# gcc <file>

raskin · 06-06-2007, 12:27 AM

No. Not with just gcc. There is a solution - to use 'make'. In simple cases you can write script that does compilation and place it near code. In complex cases you can use Autotools. You can write a shell script that will run gcc with all libraries you ever use, put it in /usr/bin and call it instead, but it is not very good as your programs will have bigger size and unneeded dependencies.

eerpini · 06-07-2007, 01:00 AM

ya i have done it , just got the required tip from the linux for you magazine ,
i jsut created an alias, using the following command , and alas it works ,.......
# alias ggl='g++ -lGL -lGLU -lGLw -lglut'
# echo "alias ggl='g++ -lGL -lGLU -lGLw -lglut'" >> ~//.bashrc

now running the command
#ggl sample.cpp
compiles the openGL graphics code in the file sample.cpp......................