--- extconf.rb.orig	2003-08-17 12:04:32.000000000 +0900
+++ extconf.rb	2004-01-31 18:22:35.000000000 +0900
@@ -52,7 +52,7 @@
 
 $objs = ["glu.o", "ogl.o", "rbogl.o"]
 #have_library("pthread", "pthread_create")
-if have_ogl_library(gl_libname) && have_ogl_library(glu_libname)
+if have_ogl_library(gl_libname, "glBegin") && have_ogl_library(glu_libname, "gluLookAt")
     create_makefile("opengl")
     File.rename("Makefile", "Makefile.ogl")
     modules = modules + "opengl.#{CONFIG['DLEXT']}" 
@@ -63,7 +63,7 @@
 end
 
 $objs = ["glut.o"]
-if have_library(glut_libname)
+if have_library(glut_libname, "glutInit")
     create_makefile("glut")
     File.rename("Makefile", "Makefile.glut")
     modules = "glut.#{CONFIG['DLEXT']} " + modules