Merge pull request #634 from nadiaholmquist/system-sdl2

cmake: Add a USE_SYSTEM_SDL2 option

CMakeLists.txt

@@ -57,6 +57,7 @@ option(ENABLE_HTTP_SERVER "Enable HTTP server. Used for Discord bot support" OFF
 option(ENABLE_DISCORD_RPC "Compile with Discord RPC support (disabled by default)" ON)
 option(ENABLE_LUAJIT "Enable scripting with the Lua programming language" ON)
 option(ENABLE_QT_GUI "Enable the Qt GUI. If not selected then the emulator uses a minimal SDL-based UI instead" OFF)
+option(USE_SYSTEM_SDL2 "Use the system's SDL2 package" OFF)
 option(ENABLE_GIT_VERSIONING "Enables querying git for the emulator version" ON)
 option(BUILD_HYDRA_CORE "Build a Hydra core" OFF)
 option(BUILD_LIBRETRO_CORE "Build a Libretro core" OFF)
@@ -145,18 +146,22 @@ if(ENABLE_DISCORD_RPC AND NOT ANDROID)
     include_directories(third_party/discord-rpc/include)
 endif()
 
-set(SDL_STATIC ON CACHE BOOL "" FORCE)
-set(SDL_SHARED OFF CACHE BOOL "" FORCE)
-set(SDL_TEST OFF CACHE BOOL "" FORCE)
 
 if (NOT ANDROID)
-    add_subdirectory(third_party/SDL2)
-    target_link_libraries(AlberCore PUBLIC SDL2-static)
+    if (USE_SYSTEM_SDL2)
+        find_package(SDL2 CONFIG REQUIRED)
+        target_link_libraries(AlberCore PUBLIC SDL2::SDL2)
+    else()
+        set(SDL_STATIC ON CACHE BOOL "" FORCE)
+        set(SDL_SHARED OFF CACHE BOOL "" FORCE)
+        set(SDL_TEST OFF CACHE BOOL "" FORCE)
+        add_subdirectory(third_party/SDL2)
+        target_link_libraries(AlberCore PUBLIC SDL2-static)
+    endif()
 endif()
 
 add_subdirectory(third_party/fmt)
 add_subdirectory(third_party/toml11)
-include_directories(${SDL2_INCLUDE_DIR})
 include_directories(third_party/toml11)
 include_directories(third_party/glm)
 include_directories(third_party/renderdoc)