How to clone only nanogui and use system-installed libraries?

[Petross404]

Hi,

I cloned nanogui to build it and install it in my Gentoo system with an ebuild. I noticed that it distributes it's own eigen and glfw libraries which:

1. I won't use, that's why package managers exist. I have installed these libs for all the projects that need them and that's it. I don't feel like wasting free disk space to duplicate code that's already there.

2. Make the size of the repo bigger and are wasting bandwidth

3. I don't get any security update if I link against the included libs.

So how can these issues can be solved for any users that agree with the previous reasons?

[Petross404]

For anyone that is interested in using the system installed libs, this patch will help you.

From 40856955ca7356f8ca0888d17eec4d05a41a27d1 Mon Sep 17 00:00:00 2001
From: Petros Siligkounas <[email protected]>
Date: Wed, 30 Sep 2020 00:07:14 +0300
Subject: [PATCH] Edit

---
 CMakeLists.txt | 166 +++++++++++--------------------------------------
 1 file changed, 35 insertions(+), 131 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8c59277df..5711c3c85 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,16 +7,19 @@ endif()
 
 project("NanoGUI")
 
+include(GNUInstallDirs) #Include this to use stantard paths
+include(FindOpenGL)
+
+find_package(OpenGL REQUIRED)
+find_package(PkgConfig REQUIRED)
+find_package(glfw3 3.3 REQUIRED)
+find_package(Eigen3 REQUIRED )
+include_directories(${EIGEN3_INCLUDE_DIR})
+
 if (POLICY CMP0058)
   cmake_policy(SET CMP0058 NEW)
 endif()
 
-if (NOT IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/ext/glfw/src")
-  message(FATAL_ERROR "The NanoGUI dependency repositories (GLFW, etc.) are missing! "
-    "You probably did not clone the project with --recursive. It is possible to recover "
-    "by calling \"git submodule update --init --recursive\"")
-endif()
-
 if (WIN32)
   set(NANOGUI_USE_GLAD_DEFAULT ON)
 else()
@@ -32,7 +35,7 @@ option(NANOGUI_INSTALL       "Install NanoGUI on `make install`?" ON)
 set(NANOGUI_PYTHON_VERSION "" CACHE STRING "Python version to use for compiling the Python plugin")
 
 # Required libraries, flags, and include files for compiling and linking against nanogui (all targets)
-set(NANOGUI_EXTRA_LIBS "")
+set(NANOGUI_EXTRA_LIBS "-lglfw")
 set(NANOGUI_EXTRA_DEFS "")
 set(NANOGUI_EXTRA_INCS "")
 
@@ -64,28 +67,6 @@ macro(CHECK_CXX_COMPILER_AND_LINKER_FLAGS _RESULT _CXX_FLAGS _LINKER_FLAGS)
   set(CMAKE_REQUIRED_LIBRARIES "")
 endmacro()
 
-# Compile GLFW
-set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL " " FORCE)
-set(GLFW_BUILD_TESTS OFF CACHE BOOL " " FORCE)
-set(GLFW_BUILD_DOCS OFF CACHE BOOL " " FORCE)
-set(GLFW_BUILD_INSTALL OFF CACHE BOOL " " FORCE)
-set(GLFW_INSTALL OFF CACHE BOOL " " FORCE)
-set(GLFW_USE_CHDIR OFF CACHE BOOL " " FORCE)
-set(BUILD_SHARED_LIBS ${NANOGUI_BUILD_SHARED} CACHE BOOL " " FORCE)
-
-if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  # Quench annoying deprecation warnings when compiling GLFW on OSX
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-deprecated-declarations")
-endif()
-
-add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/ext/glfw" "ext_build/glfw")
-# Two targets have now been defined: `glfw_objects`, which will be merged into
-# NanoGUI at the end, and `glfw`.  The `glfw` target is the library itself
-# (e.g., libglfw.so), but can be skipped as we do not need to link against it
-# (because we merge `glfw_objects` into NanoGUI).  Skipping is required for
-# XCode, but preferable for all build systems (reduces build artifacts).
-set_target_properties(glfw PROPERTIES EXCLUDE_FROM_ALL 1 EXCLUDE_FROM_DEFAULT_BUILD 1)
-
 # Python support: add NANOGUI_PYTHON flag to all targets
 if (NANOGUI_BUILD_PYTHON)
   list(APPEND NANOGUI_EXTRA_DEFS -DNANOGUI_PYTHON)
@@ -96,21 +77,6 @@ if (NANOGUI_BUILD_SHARED)
   list(APPEND NANOGUI_EXTRA_DEFS -DNANOGUI_SHARED -DNVG_SHARED -DGLAD_GLAPI_EXPORT)
 endif()
 
-if (MSVC)
-  # Disable annoying MSVC warnings (all targets)
-  add_definitions(/D "_CRT_SECURE_NO_WARNINGS")
-
-  # Parallel build on MSVC (all targets)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /MP")
-
-  if (NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:SSE2")
-
-    # Disable Eigen vectorization for Windows 32 bit builds (issues with unaligned access segfaults)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /DNANOGUI_EIGEN_DONT_ALIGN")
-  endif()
-endif()
-
 # Compile with compiler warnings turned on
 if(MSVC)
   if(CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
@@ -135,53 +101,6 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "^(GNU|Clang|Intel)$")
   endif()
 endif()
 
-# Various optimizations for shared library release builds
-if (NANOGUI_BUILD_SHARED)
-  if (U_CMAKE_BUILD_TYPE MATCHES REL AND CMAKE_CXX_COMPILER_ID MATCHES "^(GNU|Clang)$")
-    # Set the default symbol visibility to hidden
-    if (NOT CMAKE_CXX_FLAGS MATCHES "-fvisibility")
-      set(CMAKE_CXX_FLAGS "-fvisibility=hidden ${CMAKE_CXX_FLAGS}")
-    endif()
-
-    # Enable link time optimization
-    if (NOT CMAKE_CXX_FLAGS MATCHES "-flto")
-      if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-        set(LTO_CXX_FLAGS "-flto=thin")
-        set(LTO_LINKER_FLAGS "-flto=thin")
-        if (NOT APPLE AND U_CMAKE_BUILD_TYPE MATCHES MINSIZEREL)
-            # Clang Gold plugin does not support -Os
-            set(LTO_CXX_FLAGS "${LTO_CXX_FLAGS} -O3")
-        endif()
-      else()
-        set(LTO_CXX_FLAGS "-flto -fno-fat-lto-objects")
-        set(LTO_LINKER_FLAGS "-flto")
-      endif()
-
-      CHECK_CXX_COMPILER_AND_LINKER_FLAGS(HAS_LTO ${LTO_CXX_FLAGS} ${LTO_LINKER_FLAGS})
-
-      if (HAS_LTO)
-        message(STATUS "NanoGUI: LTO support enabled.")
-        set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${LTO_LINKER_FLAGS}")
-        set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${LTO_LINKER_FLAGS}")
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LTO_CXX_FLAGS}")
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${LTO_CXX_FLAGS}")
-      else()
-        message(STATUS "NanoGUI: LTO not supported by the compiler.")
-      endif()
-    endif()
-  elseif(MSVC)
-    set(Configurations RELEASE RELWITHDEBINFO MINSIZEREL)
-    set(LinkTypes EXE SHARED MODULE STATIC)
-    foreach(Configuration ${Configurations})
-      set("CMAKE_CXX_FLAGS_${Configuration}" "${CMAKE_CXX_FLAGS_${Configuration}} /GL")
-      foreach(LinkType ${LinkTypes})
-        set("CMAKE_${LinkType}_LINKER_FLAGS_${Configuration}" "${CMAKE_${LinkType}_LINKER_FLAGS_${Configuration}} /LTCG")
-      endforeach()
-    endforeach()
-    message(STATUS "NanoGUI: LTO support enabled.")
-  endif()
-endif()
-
 # Always use libc++ on Clang
 if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   CHECK_CXX_COMPILER_AND_LINKER_FLAGS(HAS_LIBCPP "-stdlib=libc++" "-stdlib=libc++")
@@ -218,15 +137,9 @@ if (NANOGUI_USE_GLAD)
 endif()
 
 list(APPEND NANOGUI_EXTRA_INCS
-  "${CMAKE_CURRENT_SOURCE_DIR}/ext/glfw/include"
   "${CMAKE_CURRENT_SOURCE_DIR}/ext/nanovg/src"
 )
 
-if (NOT NANOGUI_EIGEN_INCLUDE_DIR)
-  set(NANOGUI_EIGEN_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ext/eigen")
-  list(APPEND NANOGUI_EXTRA_INCS "${NANOGUI_EIGEN_INCLUDE_DIR}")
-endif()
-
 if (${CMAKE_SYSTEM_NAME} MATCHES "BSD")
   include_directories(/usr/local/include)
   link_directories(/usr/local/lib)
@@ -256,8 +169,25 @@ elseif(CMAKE_SYSTEM MATCHES "Linux" OR CMAKE_SYSTEM_NAME MATCHES "BSD")
   endif()
 endif()
 
-include_directories(${NANOGUI_EIGEN_INCLUDE_DIR} ext/glfw/include ext/nanovg/src include ${CMAKE_CURRENT_BINARY_DIR})
+include_directories( ext/nanovg/src include ${CMAKE_CURRENT_BINARY_DIR})
 
+# XCode has a serious bug where the XCode project produces an invalid target
+# that will not get linked if it consists only of objects from object libraries,
+# it will not generate any products (executables, libraries). The only work
+# around is to add a dummy source file to the library definition. This is an
+# XCode, not a CMake bug. See: https://itk.org/Bug/view.php?id=14044
+if (CMAKE_GENERATOR STREQUAL Xcode)
+  set(XCODE_DUMMY ${CMAKE_CURRENT_BINARY_DIR}/xcode_dummy.cpp)
+  file(WRITE ${XCODE_DUMMY} "")
+  add_library(nanogui ${NANOGUI_LIBRARY_TYPE}
+    ${XCODE_DUMMY}
+    $<TARGET_OBJECTS:nanogui-obj>
+  )
+else()
+  add_library(nanogui ${NANOGUI_LIBRARY_TYPE}
+    $<TARGET_OBJECTS:nanogui-obj>
+  )
+endif()
 
 # Run simple cmake converter to put font files into the data segment
 
@@ -352,26 +282,6 @@ add_library(nanogui-obj OBJECT
   src/serializer.cpp
 )
 
-# XCode has a serious bug where the XCode project produces an invalid target
-# that will not get linked if it consists only of objects from object libraries,
-# it will not generate any products (executables, libraries). The only work
-# around is to add a dummy source file to the library definition. This is an
-# XCode, not a CMake bug. See: https://itk.org/Bug/view.php?id=14044
-if (CMAKE_GENERATOR STREQUAL Xcode)
-  set(XCODE_DUMMY ${CMAKE_CURRENT_BINARY_DIR}/xcode_dummy.cpp)
-  file(WRITE ${XCODE_DUMMY} "")
-  add_library(nanogui ${NANOGUI_LIBRARY_TYPE}
-    ${XCODE_DUMMY}
-    $<TARGET_OBJECTS:nanogui-obj>
-    $<TARGET_OBJECTS:glfw_objects>
-  )
-else()
-  add_library(nanogui ${NANOGUI_LIBRARY_TYPE}
-    $<TARGET_OBJECTS:nanogui-obj>
-    $<TARGET_OBJECTS:glfw_objects>
-  )
-endif()
-
 if (NANOGUI_BUILD_SHARED)
   set_property(TARGET nanogui-obj PROPERTY POSITION_INDEPENDENT_CODE ON)
 endif()
@@ -385,31 +295,26 @@ if (NANOGUI_USE_GLAD AND NANOGUI_BUILD_SHARED)
 endif()
 
 if (NANOGUI_BUILD_SHARED)
-  target_link_libraries(nanogui ${NANOGUI_EXTRA_LIBS})
+  target_link_libraries(nanogui ${NANOGUI_EXTRA_LIBS})#OpenGL::GL glfw Eigen3::Eigen)
 endif()
 
 if (NANOGUI_INSTALL)
   install(TARGETS nanogui
-          LIBRARY DESTINATION lib
-          ARCHIVE DESTINATION lib)
+          LIBRARY DESTINATION ${CMAKE_INSTALL_FULL_LIBDIR}
+          ARCHIVE DESTINATION ${CMAKE_INSTALL_FULL_LIBDIR})
 
-  install(DIRECTORY include/nanogui DESTINATION include
+  install(DIRECTORY include/nanogui DESTINATION ${CMAKE_INSTALL_FULL_INCLUDEDIR}
           FILES_MATCHING PATTERN "*.h")
 endif()
 
-if (NANOGUI_BUILD_SHARED)
-  # When GLFW is merged into the NanoGUI library, this flag must be specified
-  set_property(TARGET nanogui-obj APPEND PROPERTY COMPILE_DEFINITIONS "_GLFW_BUILD_DLL;NVG_SHARED")
-endif()
-
 if (NANOGUI_BUILD_SHARED AND NOT ${U_CMAKE_BUILD_TYPE} MATCHES DEB)
   # Platform-specific strip flags for reducing the library size.
   if (APPLE)
     # Strip .dylib library on OSX
     add_custom_command(TARGET nanogui POST_BUILD COMMAND strip -u -r "$<TARGET_FILE_DIR:nanogui>/$<TARGET_FILE_NAME:nanogui>")
   elseif(UNIX)
-    # Strip .so library on Linux
-    add_custom_command(TARGET nanogui POST_BUILD COMMAND strip "$<TARGET_FILE_DIR:nanogui>/$<TARGET_FILE_NAME:nanogui>")
+    # Strip .so library on Linux - This is handled by portage, no need for this
+    # add_custom_command(TARGET nanogui POST_BUILD COMMAND strip "$<TARGET_FILE_DIR:nanogui>/$<TARGET_FILE_NAME:nanogui>")
   endif()
 endif()
 
@@ -455,8 +360,7 @@ endif()
 
 if (NANOGUI_BUILD_PYTHON)
   # Need PIC code in libnanogui even when compiled as a static library
-  set_target_properties(nanogui-obj PROPERTIES POSITION_INDEPENDENT_CODE ON)
-  set_target_properties(glfw_objects PROPERTIES POSITION_INDEPENDENT_CODE ON)
+  set_target_properties(/nanogui-obj PROPERTIES POSITION_INDEPENDENT_CODE ON)
 
   include_directories("ext/pybind11/include" ${PYTHON_INCLUDE_DIR})
   add_library(nanogui-python-obj OBJECT