Modernize CMake files

examples/opengl/CMakeLists.txt

@@ -4,13 +4,8 @@ set(SRCROOT ${PROJECT_SOURCE_DIR}/examples/opengl)
 # all source files
 set(SRC ${SRCROOT}/OpenGL.cpp)
 
-# find OpenGL
-find_package(OpenGL REQUIRED)
-include_directories(${OPENGL_INCLUDE_DIR})
-set(ADDITIONAL_LIBRARIES ${OPENGL_LIBRARIES})
-
 # define the opengl target
 sfml_add_example(opengl GUI_APP
                  SOURCES ${SRC}
-                 DEPENDS sfml-graphics sfml-window sfml-system ${ADDITIONAL_LIBRARIES}
+                 DEPENDS sfml-graphics OpenGL
                  RESOURCES_DIR resources)