Gcc -Wall implicit declaration of function

Same source as the one before:
http://u4e.us/c/main.c
http://u4e.us/c/vs1.glsl
http://u4e.us/c/fs1.glsl

It still compiles fine but I was just wondering about the warnings I get
when I compile with “gcc main.c -lSDL -lGL -Wall”

example:

warning: implicit declaration of function ‘glBindBuffer’
[-Wimplicit-function-declaration]

Are these warnings okay to ignore or am I missing something in the code
or gcc command?

Thanks again.

-Justin