build: use cmake as a build tool + include SDL2 as a submodule

[LukeUsher]

This allows compiling with ease on any supported platform, now requiring zero external dependencies.

This came about after having trouble compiling on Windows due to the MSVC project using a hard-coded path to an SDL2 installation that was not part of the repo.

[lifning]

would this require compiling SDL2 as part of building the game, as opposed to installing the library somewhere as is generally done in other projects?

i think a more idiomatic way (rather than using a git submodule and recursing) to go about using SDL2 with a CMake project, at least that i've seen, is to instruct MSVC users to download the library from https://www.libsdl.org/download-2.0.php and extract it to, say, the project directory, and then

if(MSVC)
    set(SDL2_INCLUDE_DIRS ${CMAKE_CURRENT_LIST_DIR}/SDL2/include)
    if(CMAKE_SIZEOF_VOID_P EQUAL 8) # 64 bits
        link_directories(${CMAKE_CURRENT_LIST_DIR}/SDL2/lib/x64)
    else() # 32 bits
        link_directories(${CMAKE_CURRENT_LIST_DIR}/SDL2/lib/x86)
    endif()
    set(SDL2_LIBRARIES SDL2main SDL2)
else()
    find_package(SDL2 REQUIRED)
endif()
include_directories(${SDL2_INCLUDE_DIRS})
add_executable(${PROJECT_NAME} ${SOURCE_FILES})
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})

[LukeUsher]

would this require compiling SDL2 as part of building the game, as opposed to installing the library somewhere as is generally done in other projects?

i think a more idiomatic way (rather than using a git submodule and recursing) to go about using SDL2 with a CMake project, at least that i've seen, is to instruct MSVC users to download the library from https://www.libsdl.org/download-2.0.php and extract it to, say, the project directory, and then

if(MSVC)
    set(SDL2_INCLUDE_DIRS ${CMAKE_CURRENT_LIST_DIR}/SDL2/include)
    if(CMAKE_SIZEOF_VOID_P EQUAL 8) # 64 bits
        link_directories(${CMAKE_CURRENT_LIST_DIR}/SDL2/lib/x64)
    else() # 32 bits
        link_directories(${CMAKE_CURRENT_LIST_DIR}/SDL2/lib/x86)
    endif()
    set(SDL2_LIBRARIES SDL2main SDL2)
else()
    find_package(SDL2 REQUIRED)
endif()
include_directories(${SDL2_INCLUDE_DIRS})
add_executable(${PROJECT_NAME} ${SOURCE_FILES})
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})

In most situations, I find windows users are very unlikely to want to setup external dependencies, however, it is possible to do both approaches. one approach I have done previously is to use findSDL2.cmake, but then fallback to the embedded version if a system SDL library is not found.

# Attempt to find System SDL2
find_package(SDL2)

# If it was not found, use our embedded SDL2 instead
if (NOT SDL2_FOUND)
  message(STATUS "SDL2 not installed, using embedded SDL2")
  set(SDL_STATIC ON CACHE BOOL "" FORCE)
  set(SDL_SHARED OFF CACHE BOOL "" FORCE)
  add_subdirectory(3rdParty/SDL2)
  set(SDL2_LIBRARY SDL2-static SDL2main)
  set(SDL2_INCLUDE_DIR "${SDL2_SOURCE_DIR}/include" "${SDL2_BINARY_DIR}/include")
endif()

[snesrev]

I'm not sure how this would work with Nuget on Windows...

[snesrev]

I think this is not needed now that NuGet works smoothly on Windows. Please reopen if still an issue.

[UltraHDR]

@snesrev I think this should be merged in. nuget has an old https://www.nuget.org/packages/sdl2 version from 2016 and I couldn't get the master branch compiling for Windows 11 ARM64.

I was able to compile this branch on Windows 11 ARM64 using cmake -G "Visual Studio 17 2022" -A ARM64

cmake also paves the way for other systems like the Switch.

I hope you can reconsider

Thanks