From Olaf Flebbe, "build out-of-the box on MacOSX. The default windowing system is carbon and it needs the AGL OpenGL Windowing binding framework, which is missing. osgViewer does not link therefore. Cocoa does not use AGL.

The fix adds the AGL Framework to the Carbon link line for osgViewer"

src/osgViewer/CMakeLists.txt

@@ -135,6 +135,7 @@ ELSE()
         )
 
         SET(LIB_EXTRA_LIBS ${COCOA_LIBRARY} ${LIB_EXTRA_LIBS})
+        SET(LIB_EXTRA_LIBS ${LIB_EXTRA_LIBS} "-framework AGL")
 
     ELSEIF(${OSG_WINDOWING_SYSTEM} STREQUAL "IOS")