--- /dev/null
+update: \
+ GL/glext.h \
+ GL/glxext.h \
+ GL/wglext.h \
+ EGL/egl.h \
+ EGL/eglext.h \
+ EGL/eglplatform.h \
+ KHR/khrplatform.h \
+ GLES/gl.h \
+ GLES/glext.h \
+ GLES/glplatform.h \
+ GLES2/gl2.h \
+ GLES2/gl2ext.h \
+ GLES2/gl2platform.h
+
+GL/wglext.h GL/glxext.h: FORCE
+ wget -O $@ "http://www.opengl.org/registry/api/$(@F)"
+
+GL/glext.h: GL/glext.sed FORCE
+ wget -O - "http://www.opengl.org/registry/api/$(@F)" | sed -f $*.sed > $@
+
+EGL/egl.h EGL/eglext.h EGL/eglplatform.h KHR/khrplatform.h: FORCE
+ wget -O $@ "http://www.khronos.org/registry/egl/api/$@"
+
+GLES/gl.h GLES/glext.h GLES/glplatform.h: FORCE
+ wget -O $@ "http://www.khronos.org/registry/gles/api/1.1/$(@F)"
+
+GLES2/gl2.h GLES2/gl2ext.h GLES2/gl2platform.h: FORCE
+ wget -O $@ "http://www.khronos.org/registry/gles/api/2.0/$(@F)"
+
+.PHONY: update
+
+FORCE: