submodules instead fetch content

.gitmodules

@@ -16,3 +16,12 @@
 [submodule "modules/rapidjson"]
 	path = modules/rapidjson
 	url = https://github.com/Tencent/rapidjson
+[submodule "modules/glew"]
+	path = modules/glew
+	url = https://github.com/Perlmint/glew-cmake
+[submodule "modules/glfw"]
+	path = modules/glfw
+	url = https://github.com/glfw/glfw
+[submodule "toolset/model_converter/modules/assimp"]
+	path = toolset/model_converter/modules/assimp
+	url = https://github.com/assimp/assimp

CMakeLists.txt

@@ -91,37 +91,15 @@ if(APPLE)
     find_library(Foundation Foundation)
 endif(APPLE)
 
-#
-# fetch 3rd party
-#
+set(glew-cmake_BUILD_SHARED OFF CACHE BOOL "" FORCE)
+set(glew-cmake_BUILD_MULTI_CONTEXT OFF CACHE BOOL "" FORCE)
+add_subdirectory(modules/glew)
 
-include(FetchContent)
-
-FetchContent_Declare(
-    glew
-    GIT_REPOSITORY https://github.com/Perlmint/glew-cmake)
-FetchContent_Declare(
-    glfw
-    GIT_REPOSITORY https://github.com/glfw/glfw)
-
-FetchContent_GetProperties(glew)
-FetchContent_GetProperties(glfw)
-
-if(NOT glew_POPULATED)
-    FetchContent_Populate(glew)
-    set(glew-cmake_BUILD_SHARED OFF CACHE BOOL "" FORCE)
-    set(glew-cmake_BUILD_MULTI_CONTEXT OFF CACHE BOOL "" FORCE)
-    add_subdirectory(${glew_SOURCE_DIR} ${glew_BINARY_DIR})
-endif()
-
-if(NOT glfw_POPULATED)
-    FetchContent_Populate(glfw)
-    set(GLFW_INSTALL OFF CACHE BOOL "" FORCE)
-    set(GLFW_BUILD_DOCS OFF CACHE BOOL "" FORCE)
-    set(GLFW_BUILD_TESTS OFF CACHE BOOL "" FORCE)
-    set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
-    add_subdirectory(${glfw_SOURCE_DIR} ${glfw_BINARY_DIR})
-endif()
+set(GLFW_INSTALL OFF CACHE BOOL "" FORCE)
+set(GLFW_BUILD_DOCS OFF CACHE BOOL "" FORCE)
+set(GLFW_BUILD_TESTS OFF CACHE BOOL "" FORCE)
+set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
+add_subdirectory(modules/glfw)
 
 #
 # e2d library target
@@ -140,8 +118,8 @@ source_group(TREE ${CMAKE_CURRENT_SOURCE_DIR} FILES
 target_include_directories(${PROJECT_NAME}
     PRIVATE headers
     PRIVATE sources
-    PRIVATE ${glew_SOURCE_DIR}/include
-    PRIVATE ${glfw_SOURCE_DIR}/include)
+    PRIVATE modules/glew/include
+    PRIVATE modules/glfw/include)
 
 set_target_properties(${PROJECT_NAME} PROPERTIES
     CXX_STANDARD 14

toolset/model_converter/CMakeLists.txt

@@ -1,23 +1,11 @@
 #
-# fetch 3rd party
+# external 3rd party
 #
 
-include(FetchContent)
-
-FetchContent_Declare(
-    assimp
-    GIT_REPOSITORY https://github.com/assimp/assimp)
-
-FetchContent_GetProperties(assimp)
-
-if(NOT assimp_POPULATED)
-    FetchContent_Populate(assimp)
-    set(BUILD_SHARED_LIBS OFF CACHE BOOL "" FORCE)
-    set(ASSIMP_NO_EXPORT ON CACHE BOOL "" FORCE)
-    set(ASSIMP_BUILD_TESTS OFF CACHE BOOL "" FORCE)
-    set(ASSIMP_BUILD_ASSIMP_TOOLS OFF CACHE BOOL "" FORCE)
-    add_subdirectory(${assimp_SOURCE_DIR} ${assimp_BINARY_DIR})
-endif()
+set(ASSIMP_NO_EXPORT ON CACHE BOOL "" FORCE)
+set(ASSIMP_BUILD_TESTS OFF CACHE BOOL "" FORCE)
+set(ASSIMP_BUILD_ASSIMP_TOOLS OFF CACHE BOOL "" FORCE)
+add_subdirectory(modules/assimp)
 
 #
 # model converter executable
@@ -35,10 +23,6 @@ add_executable(model_converter
 target_link_libraries(model_converter
     assimp)
 
-target_include_directories(model_converter
-    PRIVATE ${assimp_SOURCE_DIR}/include
-    PRIVATE ${assimp_BINARY_DIR}/include)
-
 set_target_properties(model_converter PROPERTIES
     CXX_STANDARD 14
     CXX_STANDARD_REQUIRED YES