Trouble installing GtkGlArea

[jca <jca mail phm vcu edu>]

  I downloaded the GtkGlArea widget from:
http://www.student.oulu.fi/~jlof/gtkglarea/index.html

  And, following the instructions, ran configure (worked fine), and then
make, and got this error:
  gdkgl.c:33: GL/gl.h: No such file or directory
  gdkgl.c:34: GL/glx.h: No such file or directory
  make[1]: *** [gdkgl.lo] Error 1

  Ok, so I'm missing a library of some kind.  Where do I get this
library and what is its full name?

  Thanks,
  jca