-# define SG_GL_H <OpenGL/gl.h>
-# define SG_GLX_H <AGL/agl.h>
-# define SG_GLU_H <OpenGL/glu.h>
-# define SG_GLEXT_H <OpenGL/glext.h>
-# define SG_GLUT_H <GLUT/glut.h>
+# define SG_MAC
+# define SG_UNIX
+# ifdef __GNUC__
+# if ( __GNUC__ > 3 ) || ( __GNUC__ == 3 && __GNUC_MINOR__ >= 3 )
+inline int (isnan)(double r) { return !(r <= 0 || r >= 0); }
+# else
+ // any C++ header file undefines isinf and isnan
+ // so this should be included before <iostream>
+ // the functions are STILL in libm (libSystem on mac os x)
+extern "C" int (isnan)(double);
+extern "C" int (isinf)(double);
+# endif
+# else
+inline int (isnan)(double r) { return !(r <= 0 || r >= 0); }
+# endif
+#endif
+
+#if defined (__FreeBSD__)
+# define SG_UNIX
+#include <sys/param.h>
+# if __FreeBSD_version < 500000
+ extern "C" {
+ inline int isnan(double r) { return !(r <= 0 || r >= 0); }
+ }
+# endif
+#endif