glutExtensionSupported
GLUTAPI int GLUTAPIENTRY glutExtensionSupported(const char *name);
{ "glutExtensionSupported", (const GLUTproc) glutExtensionSupported },
else if (glutExtensionSupported("GL_ARB_vertex_shader")
&& glutExtensionSupported("GL_ARB_fragment_shader")
&& glutExtensionSupported("GL_ARB_shader_objects")) {