+//
+// Platform dependent gl.h and glut.h definitions
+//
+
+#ifdef __APPLE__
+# 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>
+
+inline int (isnan)(double r) { return !(r <= 0 || r >= 0); }
+#else
+# define SG_GL_H <GL/gl.h>
+# define SG_GLX_H <GL/glx.h>
+# define SG_GLU_H <GL/glu.h>
+# define SG_GLEXT_H <GL/glext.h>
+# define SG_GLUT_H <GL/glut.h>
+#endif
+
+