made project use FetchContent insteaf of relying on submodules

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.14)
 
 project(Geometry VERSION 0.1 LANGUAGES CXX)
 
@@ -8,9 +8,16 @@ endif ()
 
 set(CMAKE_CXX_STANDARD 17)
 
-include_directories(${PROJECT_SOURCE_DIR}/include)
+include(FetchContent)
 
-add_subdirectory(lib/eigen)
+FetchContent_Declare(
+        eigen
+        GIT_REPOSITORY https://gitlab.com/libeigen/eigen.git
+        GIT_TAG 3.4.0
+)
+FetchContent_MakeAvailable(eigen)
+
+include_directories(${PROJECT_SOURCE_DIR}/include)
 
 add_subdirectory(src)
 

app/CMakeLists.txt

@@ -1,5 +1,3 @@
 add_executable(Geometry main.cpp)
 
 target_link_libraries(Geometry PUBLIC Eigen3::Eigen)
-
-target_include_directories(Geometry PUBLIC "${PROJECT_BINARY_DIR}" "${PROJECT_SOURCE_DIR}/lib/eigen/Eigen")

include/main.h

@@ -6,7 +6,7 @@
 #define GEOMETRY_MAIN_H
 
 #include <iostream>
-#include <Dense>
+#include <Eigen/Dense>
 
 using namespace std;