Build - Vendor Eigen 3.4.0 into mmSolverLibs

This is to avoid having to download anything at build time.

Author: david-cattermole

CMakeLists.txt

@@ -129,6 +129,16 @@ include(MMSolverUtils)
 add_subdirectory(share)
 
 if (MMSOLVER_BUILD_PLUGIN)
+  # Set up vendored Eigen variables for external dependencies that need them
+  set(eigen_vendored_dir "${CMAKE_CURRENT_SOURCE_DIR}/lib/thirdparty/eigen")
+  if(EXISTS "${eigen_vendored_dir}")
+    set(Eigen3_FOUND TRUE)
+    set(Eigen3_VERSION "3.4.0")
+    set(Eigen3_INCLUDE_DIR "${eigen_vendored_dir}")
+    set(Eigen3_INCLUDE_DIRS "${eigen_vendored_dir}")
+    message(STATUS "Set up vendored Eigen variables for main build dependencies: ${eigen_vendored_dir}")
+  endif()
+
   # Finds and builds external (third-party) dependencies.
   #
   # NOTE: Dependencies are handled in mmsolverlibs sub-project.

lib/CMakeLists.txt

@@ -96,6 +96,17 @@ message(STATUS "Rust Depend On Libraries: ${rust_depend_on_libraries}")
 # Build options for mmsolverlibs dependencies are inherited from
 # parent scope.
 
+# Set up vendored Eigen variables for external dependencies that need
+# them.
+set(eigen_vendored_dir "${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/eigen")
+if(EXISTS "${eigen_vendored_dir}")
+  set(Eigen3_FOUND TRUE)
+  set(Eigen3_VERSION "3.4.0")
+  set(Eigen3_INCLUDE_DIR "${eigen_vendored_dir}")
+  set(Eigen3_INCLUDE_DIRS "${eigen_vendored_dir}")
+  message(STATUS "Set up vendored Eigen variables for dependencies: ${eigen_vendored_dir}")
+endif()
+
 # Finds and builds external (third-party) dependencies for
 # mmsolverlibs.
 include(FindAndBuildMmsolverDependencies)

lib/share/cmake/modules/FindAndBuildMmsolverDependencies.cmake

@@ -52,17 +52,6 @@ find_package(glog 0.7.1 REQUIRED)
 # https://github.com/devernay/cminpack
 find_package(cminpack 1.3.8 REQUIRED)
 
-# Eigen - Linear Algebra library
-#
-# https://gitlab.com/libeigen/eigen
-#
-# Eigen is used by both Ceres and OpenMVG and provides data types
-# shared across the ABI boundary and is also used in mmSolver. Eigen
-# also supplies a sparse-matrix that is used by Ceres.
-#
-# v3.4.0 is also the version used by OpenMVG.
-find_package(Eigen3 3.4.0 REQUIRED)
-
 # Ceres Solver - Non-Linear Least-Squares Fits solver
 #
 # Ceres Solver is used by OpenMVG for various least-squares

lib/thirdparty/CMakeLists.txt

@@ -19,4 +19,5 @@
 # Building third-party projects.
 #
 
+add_subdirectory(eigen)
 add_subdirectory(openMVG)

lib/thirdparty/eigen/.clang-format

@@ -0,0 +1,19 @@
+---
+BasedOnStyle: Google
+ColumnLimit:  120
+---
+Language:     Cpp
+BasedOnStyle: Google
+ColumnLimit:  120
+StatementMacros:
+  - EIGEN_STATIC_ASSERT
+  - EIGEN_INITIALIZE_COEFFS_IF_THAT_OPTION_IS_ENABLED
+  - EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN
+SortIncludes: false
+AttributeMacros:
+- EIGEN_STRONG_INLINE
+- EIGEN_ALWAYS_INLINE
+- EIGEN_DEVICE_FUNC
+- EIGEN_DONT_INLINE
+- EIGEN_DEPRECATED
+- EIGEN_UNUSED

lib/thirdparty/eigen/CMakeLists.txt

@@ -0,0 +1,99 @@
+# Copyright (C) 2025 David Cattermole.
+#
+# This file is part of mmSolver.
+#
+# mmSolver is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# mmSolver is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with mmSolver.  If not, see <https://www.gnu.org/licenses/>.
+# ---------------------------------------------------------------------
+#
+# CMakeLists.txt for vendored Eigen.
+#
+# Eigen is a header-only C++ template library for linear algebra:
+# matrices, vectors, numerical solvers, and related algorithms.
+#
+# This vendored copy ensures consistent version across all build environments
+# and eliminates external dependency management.
+#
+
+# Eigen is a header-only library, so we create an INTERFACE target
+# Create 'eigen' target (Eigen3 target may already exist from parent CMake)
+add_library(eigen INTERFACE)
+
+# Only create Eigen3 target if it doesn't already exist
+if(NOT TARGET Eigen3)
+  add_library(Eigen3 INTERFACE)
+endif()
+
+# Only create Eigen3::Eigen alias if it doesn't already exist
+if(NOT TARGET Eigen3::Eigen)
+  add_library(Eigen3::Eigen ALIAS eigen)
+endif()
+
+# Set the include directory for the Eigen headers
+set(eigen_include_dir "${CMAKE_CURRENT_SOURCE_DIR}")
+
+# Set interface include directories for eigen target
+target_include_directories(eigen INTERFACE
+  $<BUILD_INTERFACE:${eigen_include_dir}>
+  $<INSTALL_INTERFACE:include/>
+)
+
+# Set interface include directories for Eigen3 target if we created it here
+# (If it was created earlier, it should already have the correct paths)
+get_target_property(eigen3_include_dirs Eigen3 INTERFACE_INCLUDE_DIRECTORIES)
+if(NOT eigen3_include_dirs OR eigen3_include_dirs STREQUAL "eigen3_include_dirs-NOTFOUND")
+  target_include_directories(Eigen3 INTERFACE
+    $<BUILD_INTERFACE:${eigen_include_dir}>
+    $<INSTALL_INTERFACE:include/>
+  )
+endif()
+
+# Set C++ standard requirement (Eigen 3.4.0 requires C++14 minimum)
+target_compile_features(eigen INTERFACE cxx_std_14)
+
+# Set C++ standard for Eigen3 if we created it here
+get_target_property(eigen3_cxx_features Eigen3 INTERFACE_COMPILE_FEATURES)
+if(NOT eigen3_cxx_features OR eigen3_cxx_features STREQUAL "eigen3_cxx_features-NOTFOUND")
+  target_compile_features(Eigen3 INTERFACE cxx_std_14)
+endif()
+
+# Install Eigen headers - now properly organized in Eigen subdirectory
+install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/Eigen/
+        DESTINATION include/Eigen
+        FILES_MATCHING PATTERN "*" PATTERN "*.h" PATTERN "*.hpp")
+
+install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/unsupported
+        DESTINATION include
+        FILES_MATCHING PATTERN "*.h" PATTERN "*.hpp")
+
+# Install Eigen targets
+include(MMCommonUtils)
+mm_common_install_target_library("mmsolverlibs_cpp" eigen)
+# Note: Eigen3 target is exported early in the main CMakeLists.txt to resolve dependency ordering
+
+# Set version information
+set_target_properties(eigen PROPERTIES
+  VERSION "3.4.0"
+  EXPORT_NAME "Eigen3::Eigen"
+)
+
+# Set properties for Eigen3 if we created it here
+if(TARGET Eigen3)
+  get_target_property(eigen3_version Eigen3 VERSION)
+  if(NOT eigen3_version OR eigen3_version STREQUAL "eigen3_version-NOTFOUND")
+    set_target_properties(Eigen3 PROPERTIES
+      VERSION "3.4.0"
+      EXPORT_NAME "Eigen3"
+    )
+  endif()
+endif()

lib/thirdparty/eigen/COPYING.APACHE

@@ -0,0 +1,203 @@
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