fix linux GUI compilation

CMakeLists.txt

@@ -18,7 +18,7 @@
 # Website: https://project.inria.fr/crowdscience/
 # See the file AUTHORS.md for a list of all contributors.
 
-cmake_minimum_required( VERSION 2.8 )
+cmake_minimum_required( VERSION 3.10 )
 project( UMANS )
 set (CMAKE_CXX_STANDARD 17)
 
@@ -77,23 +77,29 @@ target_link_libraries(UMANS-Library Engine)
 
 if (UMANS_USE_GUI_APPLICATION)
 
-	set(CMAKE_AUTOMOC ON)
+	# necessary: gives the path to GUI src files to qt autogen files
+	include_directories( ./src/GUI/ )
+
+	# set autogen variables for qt
+	set(CMAKE_INCLUDE_CURRENT_DIR ON)
 	set(CMAKE_AUTOUIC ON)
-	set (CMAKE_INCLUDE_CURRENT_DIR ON)
-	# --- NOTE: To let this line work, add the following environment variable:
-	#	  CMAKE_PREFIX_PATH
-	#     with a value such as C:\Qt\5.12.0\msvc2017_64 (depending on your Qt installation)
-	find_package(Qt5 COMPONENTS Core Widgets REQUIRED)
+	set(CMAKE_AUTOMOC ON)
+	set(CMAKE_AUTORCC ON)
+	
+	# find relevant packages
+	find_package(Qt5Core REQUIRED)
+	find_package(Qt5Widgets REQUIRED)
+	find_package(OpenGL REQUIRED)
 
 	# --- include the Qt resources, so that the application icon gets shown
-	set(UI_RESOURCES src/GUI/UMANSQtGuiApplication.qrc )
+	set(UI_RESOURCES src/GUI/UMANSQtGuiApplication.qrc)
 	qt5_add_resources(UI_RESOURCES_RCC ${UI_RESOURCES})
-
+	
 	# --- define the project itself
-	add_executable(UMANS-GUI src/GUI/main.cpp ${src_GUI} ${UI_RESOURCES_RCC})
+	add_executable(UMANS-GUI src/GUI/main.cpp ${src_GUI} ${UI_RESOURCES_RCC} ${UI_HEADERS})
 
 	# --- the project depends on some libraries
-	target_link_libraries(UMANS-GUI Engine Qt5::Widgets opengl32.lib glu32.lib)
+	target_link_libraries(UMANS-GUI Engine Qt5::Core Qt5::Widgets ${OPENGL_LIBRARIES})
 
 	# --- post-build command: copy the required Qt DLLs, to prevent runtime errors
 	add_custom_command(TARGET UMANS-GUI POST_BUILD