From Eric Sokolowski, "Fixed the build of the osgViewer library to get GL/glx.h from the right place, when building on OSX with X11"

src/osgViewer/CMakeLists.txt

@@ -35,6 +35,7 @@ SET(LIB_COMMON_FILES
     ViewerEventHandlers.cpp
 )
 
+SET(LIB_EXTRA_LIBS)
 
 IF(WIN32)
 
@@ -89,9 +90,26 @@ ELSE(WIN32)
             PKG_CHECK_MODULES(XRANDR REQUIRED xrandr)
             ADD_DEFINITIONS(-DOSGVIEWER_USE_XRANDR)
             SET(LIB_PUBLIC_HEADERS ${LIB_PUBLIC_HEADERS} ${XRANDR_INCLUDE_DIRS})
-        LINK_LIBRARIES(Xrandr)
+            LINK_LIBRARIES(Xrandr)
         ENDIF(OSGVIEWER_USE_XRANDR)
 
+        # X11 on Apple requires X11 library plus OpenGL linking hack on Leopard
+        IF(APPLE)
+            # Find GL/glx.h 
+            IF(EXISTS ${CMAKE_OSX_SYSROOT}/usr/X11/include/GL/glx.h)
+                SET(OPENGL_INCLUDE_DIR /usr/X11/include)
+                SET(OPENGL_LIBRARIES /usr/X11/lib/libGL.dylib)
+            ELSEIF(EXISTS ${CMAKE_OSX_SYSROOT}/usr/X11R6/include/GL/glx.h)
+                SET(OPENGL_INCLUDE_DIR /usr/X11R6/include)
+                SET(OPENGL_LIBRARIES /usr/X11R6/lib/libGL.dylib)
+            ENDIF(EXISTS ${CMAKE_OSX_SYSROOT}/usr/X11/include/GL/glx.h)
+            INCLUDE_DIRECTORIES(BEFORE SYSTEM ${OPENGL_INCLUDE_DIR})
+
+            SET(LIB_EXTRA_LIBS ${X11_X11_LIB} ${OPENGL_LIBRARIES} ${LIB_EXTRA_LIBS})
+            SET(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -Wl,-dylib_file,/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib:${CMAKE_OSX_SYSROOT}/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib")
+        ENDIF(APPLE)
+            
+
     ENDIF(${OSG_WINDOWING_SYSTEM} STREQUAL "Carbon")
 
 ENDIF(WIN32)
@@ -112,6 +130,7 @@ LINK_INTERNAL(${LIB_NAME}
     osgUtil
     osg
     OpenThreads
+    ${LIB_EXTRA_LIBS}
 )
 
 LINK_CORELIB_DEFAULT(${LIB_NAME})