Feature/eigen free (#64)

* Change the place of option

* Make the dependency of Eigen free

* (minor) remove "" for consistency

cpp/CMakeLists.txt

@@ -1,6 +1,9 @@
 cmake_minimum_required(VERSION 3.11)
 project(patchworkpp VERSION 1.0.1)
 
+option(USE_SYSTEM_EIGEN3 "Use system pre-installed Eigen" OFF)
+option(INCLUDE_CPP_EXAMPLES "Include C++ example codes, which require Open3D for visualization" OFF)
+
 set(CMAKE_CXX_STANDARD 20)
 set(PYTHON_EXECUTABLE python3)
 set(CMAKE_BUILD_TYPE Release)
@@ -10,14 +13,32 @@ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${Open3D_C_FLAGS}")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${Open3D_CXX_FLAGS}")
 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${Open3D_EXE_LINKER_FLAGS}")
 
-if(CMAKE_VERSION VERSION_LESS "3.15")
+if(CMAKE_VERSION VERSION_LESS 3.15)
   include("${CMAKE_CURRENT_SOURCE_DIR}/cmake/ListPrepend.cmake")
   list_prepend(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 else()
   list(PREPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 endif()
 
-option(INCLUDE_CPP_EXAMPLES "Include C++ example codes, which require Open3D for visualization" OFF)
+if(CMAKE_VERSION VERSION_GREATER 3.24)
+  cmake_policy(SET CMP0135 OLD)
+endif()
+
+# Originally, below code was from `find_dependencies.cmake`
+# The below code is to make dependency of Eigen free
+function(find_external_dependency PACKAGE_NAME TARGET_NAME INCLUDED_CMAKE_PATH)
+  string(TOUPPER ${PACKAGE_NAME} PACKAGE_NAME_UP)
+  set(USE_FROM_SYSTEM_OPTION "USE_SYSTEM_${PACKAGE_NAME_UP}")
+  if(${${USE_FROM_SYSTEM_OPTION}})
+    find_package(${PACKAGE_NAME} QUIET NO_MODULE)
+  endif()
+  if(NOT ${${USE_FROM_SYSTEM_OPTION}} OR NOT TARGET ${TARGET_NAME})
+    set(${USE_FROM_SYSTEM_OPTION} OFF PARENT_SCOPE)
+    include(${INCLUDED_CMAKE_PATH})
+  endif()
+endfunction()
+
+find_external_dependency("Eigen3" "Eigen3::Eigen" "${CMAKE_CURRENT_LIST_DIR}/cmake/eigen.cmake")
 
 # Parameters in `patchworkpp` subdirectory.
 # Thus, link should be `patchworkpp::ground_seg_cores`

cpp/cmake/LICENSE

@@ -0,0 +1,18 @@
+Eigen is primarily MPL2 licensed. See COPYING.MPL2 and these links:
+  http://www.mozilla.org/MPL/2.0/
+  http://www.mozilla.org/MPL/2.0/FAQ.html
+
+Some files contain third-party code under BSD or LGPL licenses, whence the other
+COPYING.* files here.
+
+All the LGPL code is either LGPL 2.1-only, or LGPL 2.1-or-later.
+For this reason, the COPYING.LGPL file contains the LGPL 2.1 text.
+
+If you want to guarantee that the Eigen code that you are #including is licensed
+under the MPL2 and possibly more permissive licenses (like BSD), #define this
+preprocessor symbol:
+  EIGEN_MPL2_ONLY
+For example, with most compilers, you could add this to your project CXXFLAGS:
+  -DEIGEN_MPL2_ONLY
+This will cause a compilation error to be generated if you #include any code that is
+LGPL licensed.

cpp/cmake/eigen.cmake

@@ -0,0 +1,47 @@
+# MIT License
+#
+# Copyright (c) 2022 Ignacio Vizzo, Tiziano Guadagnino, Benedikt Mersch, Cyrill
+# Stachniss.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+set(EIGEN_BUILD_DOC OFF CACHE BOOL "Don't build Eigen docs")
+set(EIGEN_BUILD_TESTING OFF CACHE BOOL "Don't build Eigen tests")
+set(EIGEN_BUILD_PKGCONFIG OFF CACHE BOOL "Don't build Eigen pkg-config")
+set(EIGEN_BUILD_BLAS OFF CACHE BOOL "Don't build blas module")
+set(EIGEN_BUILD_LAPACK OFF CACHE BOOL "Don't build lapack module")
+
+include(FetchContent)
+FetchContent_Declare(eigen URL https://gitlab.com/libeigen/eigen/-/archive/3.4.0/eigen-3.4.0.tar.gz
+                     PATCH_COMMAND patch -p1 < ${CMAKE_CURRENT_LIST_DIR}/eigen.patch UPDATE_DISCONNECTED 1)
+FetchContent_GetProperties(eigen)
+if(NOT eigen_POPULATED)
+  FetchContent_Populate(eigen)
+  if(${CMAKE_VERSION} GREATER_EQUAL 3.25)
+    add_subdirectory(${eigen_SOURCE_DIR} ${eigen_BINARY_DIR} SYSTEM EXCLUDE_FROM_ALL)
+  else()
+    # Emulate the SYSTEM flag introduced in CMake 3.25. Withouth this flag the compiler will
+    # consider this 3rdparty headers as source code and fail due the -Werror flag.
+    add_subdirectory(${eigen_SOURCE_DIR} ${eigen_BINARY_DIR} EXCLUDE_FROM_ALL)
+    get_target_property(eigen_include_dirs eigen INTERFACE_INCLUDE_DIRECTORIES)
+    set_target_properties(eigen PROPERTIES INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${eigen_include_dirs}")
+  endif()
+endif()
+
+

cpp/cmake/eigen.patch

@@ -0,0 +1,74 @@
+commit cf82186416d04ea5df2a397d8fe09dc78d40ca65
+Author: Antonio Sánchez <cantonios@google.com>
+Date:   Sat Mar 5 05:49:45 2022 +0000
+
+    Adds new CMake Options for controlling build components.
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index de1c23e91..0af36a53a 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -477,6 +477,9 @@ if(EIGEN_BUILD_TESTING)
+   add_subdirectory(failtest)
+ endif()
+
++include(CMakeDetermineFortranCompiler)
++option(EIGEN_BUILD_BLAS "Toggles the building of the Eigen Blas library" ${CMAKE_Fortran_COMPILER})
++option(EIGEN_BUILD_LAPACK "Toggles the building of the included Eigen LAPACK library" ${CMAKE_Fortran_COMPILER})
+ if(EIGEN_LEAVE_TEST_IN_ALL_TARGET)
+   add_subdirectory(blas)
+   add_subdirectory(lapack)
+@@ -611,6 +614,8 @@ set_target_properties (eigen PROPERTIES EXPORT_NAME Eigen)
+
+ install (TARGETS eigen EXPORT Eigen3Targets)
+
++option(EIGEN_BUILD_CMAKE_PACKAGE "Enables the creation of EigenConfig.cmake and related files" ON)
++if(EIGEN_BUILD_CMAKE_PACKAGE)
+ configure_package_config_file (
+   ${CMAKE_CURRENT_SOURCE_DIR}/cmake/Eigen3Config.cmake.in
+   ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
+@@ -655,6 +660,7 @@ install (FILES ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
+ # Add uninstall target
+ add_custom_target ( uninstall
+     COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/EigenUninstall.cmake)
++endif()
+
+ if (EIGEN_SPLIT_TESTSUITE)
+   ei_split_testsuite("${EIGEN_SPLIT_TESTSUITE}")
+diff --git a/blas/CMakeLists.txt b/blas/CMakeLists.txt
+index 8d3cb86dc..c530957fb 100644
+--- a/blas/CMakeLists.txt
++++ b/blas/CMakeLists.txt
+@@ -1,6 +1,7 @@
+
+ project(EigenBlas CXX)
+
++if(EIGEN_BUILD_BLAS)
+ include(CheckLanguage)
+ check_language(Fortran)
+ if(CMAKE_Fortran_COMPILER)
+@@ -59,4 +60,4 @@ if(EIGEN_BUILD_TESTING)
+ endif()
+
+ endif()
+-
++endif()
+diff --git a/lapack/CMakeLists.txt b/lapack/CMakeLists.txt
+index c8ca64001..8d6d75401 100644
+--- a/lapack/CMakeLists.txt
++++ b/lapack/CMakeLists.txt
+@@ -1,5 +1,7 @@
+ project(EigenLapack CXX)
+
++if(EIGEN_BUILD_LAPACK AND EIGEN_BUILD_BLAS)
++
+ include(CheckLanguage)
+ check_language(Fortran)
+ if(CMAKE_Fortran_COMPILER)
+@@ -457,3 +459,6 @@ if(EXISTS ${eigen_full_path_to_testing_lapack})
+
+ endif()
+
++elseif(EIGEN_BUILD_LAPACK AND NOT EIGEN_BUILD_BLAS)
++ message(FATAL_ERROR "EIGEN_BUILD_LAPACK requires EIGEN_BUILD_BLAS")
++endif() #EIGEN_BUILD_LAPACK

cpp/patchworkpp/CMakeLists.txt

@@ -3,9 +3,6 @@ project(patchworkpp_src)
 include(GNUInstallDirs)
 
 message("Parent project name: " ${PARENT_PROJECT_NAME})
-
-find_package(Eigen3 REQUIRED QUIET)
-
 add_library(${TARGET_NAME} STATIC src/patchworkpp.cpp)
 set_target_properties(${TARGET_NAME} PROPERTIES POSITION_INDEPENDENT_CODE ON)