无法使用 cmake

如何解决无法使用 cmake

我正在制作一个项目，其中包含一个 deps 文件夹及其所有依赖项，目前它包含 SDL2 和 SDL2_ttf 的 git clone。例如，我想让这个项目工作而不必单独安装 SDL2 或 SDL2_ttf 使用自制软件。我目前的做法是执行以下操作，但是，SDL2_ttf 似乎无法找到 SDL2 的目录，我该如何解决？

CMakelists.txt

cmake_minimum_required(VERSION 3.19)
project(app)

add_executable(app MACOSX_BUNDLE src/main.cpp)

# SDL2
add_subdirectory(deps/SDL2)
add_dependencies(app SDL2)

# SDL2_ttf
add_subdirectory(deps/SDL2_ttf)
add_dependencies(app SDL2_ttf)

错误信息

CMake Error at deps/SDL2_ttf/CMakeLists.txt:12 (find_package):
  By not providing "FindSDL2.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "SDL2",but
  CMake did not find one.

  Could not find a package configuration file provided by "SDL2" with any of
  the following names:

    SDL2Config.cmake
    sdl2-config.cmake

  Add the installation prefix of "SDL2" to CMAKE_PREFIX_PATH or set
  "SDL2_DIR" to a directory containing one of the above files.  If "SDL2"
  provides a separate development package or SDK,be sure it has been
  installed.

附言我尝试按照错误中的建议在我的 CMakeLists.txt 中执行 SET(SDL2_DIR deps/SDL2) ，但这似乎不起作用，我收到相同的错误消息。

SDL2 确实包含 SDL2Config.cmake，我正在使用这些 repos 的最新 master： https://github.com/libsdl-org/SDL https://github.com/libsdl-org/SDL_ttf