Better handling for the library-vs.-framework issue for OpenGL and GLUT.

Using find_library now which does the right thing regardless of which OS we're building on (I think - I haven't been able to test it on Linux yet).

CMakeLists.txt

@@ -5,6 +5,8 @@ cmake_minimum_required(VERSION 2.6)
 # General build properties
 file(GLOB VGL_SOURCES src/*.cpp thirdparty/*.c)
 file(GLOB VGL_HEADERS src/*.h)
+find_library(OpenGL_LIB OpenGL gl)
+find_library(GLUT_LIB GLUT glut)
 
 include_directories(src thirdparty /opt/local/include)
 link_directories(/opt/local/lib)
@@ -13,33 +15,22 @@ link_directories(/opt/local/lib)
 # Helper function which creates an example program.
 function (example example_NAME)
   add_executable(${example_NAME} example/${example_NAME}.cpp)
-  target_link_libraries(${example_NAME} vgl ${VGL_LIBS})
-  if (${APPLE})
-    set_target_properties(${example_NAME} PROPERTIES LINK_FLAGS "-framework OpenGL -framework GLUT")
-  endif(${APPLE})
+  target_link_libraries(${example_NAME} vgl)
   install(TARGETS ${example_NAME} DESTINATION bin)
 endfunction(example)
 
 # Helper function which creates a test program.
 function (test test_NAME)
   add_executable(${test_NAME} test/${test_NAME}.cpp)
   target_link_libraries(${test_NAME} vgl cppunit)
-  if (${APPLE})
-    set_target_properties(${test_NAME} PROPERTIES LINK_FLAGS "-framework OpenGL -framework GLUT")
-  endif(${APPLE})
   install(TARGETS ${test_NAME} DESTINATION bin)
   add_test(NAME run-${test_NAME} COMMAND ${test_NAME})
 endfunction(test)
 
 
 # The VGL shared library
 add_library(vgl SHARED ${VGL_SOURCES} ${VGL_THIRDPARTY_SOURCES})
-if (${APPLE})
-  target_link_libraries(vgl png jpeg tiff)
-  set_target_properties(vgl PROPERTIES LINK_FLAGS "-framework OpenGL -framework GLUT")
-else(${APPLE})
-  target_link_libraries(vgl glut pthread png jpeg tiff)
-endif(${APPLE})
+target_link_libraries(vgl ${OpenGL_LIB} ${GLUT_LIB} pthread png jpeg tiff)
 install(FILES ${VGL_HEADERS} DESTINATION dist/include)
 install(TARGETS vgl LIBRARY DESTINATION dist/lib)