Begin Linux OpenGL programming

• Compiling an OpenGL/GLUT program requires you to use a number of libraries.
  
  
  
  • GLUT (library "glut" on Linux)
    
  • OpenGL (library "GL" on Linux)
    
  • GL Utilities (library "GLU" on Linux)
    
  • Windowing specific libraries needed by GLUT. For X-Windows, these include:
    
    
    
    • X11
      
    • Xmu
      
    • Xi
      
    
    
  • Often you'll also need the math library (library "m" on Linux)
    
  • You need to include (more) libraries if you encounter error messages such as:
    
    
    
    • /tmp/ccKfrBZc.o(.text+0x1a6): In function `main':
      
      : undefined reference to `glutInitDisplayMode'
      
    
    
  
  
  
• Including libraries is easy with gcc or g++, just at "-l< lib-name >" to the command line.
  
  
  
• So, a compilation including all these libraries would look like:
  
  
  
  • gcc -o myProg myProg.c -lglut -lGL -lGLU -lX11 -lXmu -lXi -lm
    
  • The "-o myProg" tells gcc to call the executable "myProg"
    
  • After compilation, you can run by typing "./myProg" or if "." is in your path just "myProg" will work.
    
  
  
  
• On many machines, gcc doesn't know where to find the correct include
  files (those you added to your code using #include"...")
  
  
  
  • Adding "-I < include-path >" tells gcc where to find additional include files.
    
  • You'll need to add -I commands to eliminate errors such as:
    
    
    
    • myProg.c:1:17: Xm.h: No such file or directory
      
    
    
  
  
  
  
• Often (including on the lab machines), the linker doesn't know where to find
  some of the libraries if they're stored in unusual locations (like outside of /usr/lib)
  
  
  
  • Adding "-L < library-path >" tells the linker where to find additional library files.
    
  • You'll need to add -L commands to eliminate errors such as:
    
    
    
    • /usr/bin/ld: cannot find -lX11
      
    
    
  
  

Suggested Command Line to Compile on Lab Machines:

gcc -o myProg myProg.c -I /usr/X11R6/include/ -L /usr/X11R6/lib64/ -lglut -lGL -lGLU -lX11 -lXmu -lXi -lm

You should just be able to copy/paste. The only changes you need to make are:

• Change the filename "myProg.c" to the filename of your program
  
  
  
  • (If you have more than one C file, include more than one on the command line)
    
  
  
• Change "gcc" to "g++" if you're using C++.
  

NOTE: If you are compiling at home, you may need to change /usr/X11R6/lib64 to
/usr/X11R6/lib. It turns out the lab machines in MLH 301 have both 32- and 64-bit versions
of OpenGL and GLU, but only a 64-bit version of GLUT.

---

Chris Wyman (cwyman@cs.uiowa.edu)