编译ORB-SLAM3时CMake无法识别epoxy库的问题求助

问题现象 #

编译ORB-SLAM3时出现链接错误：

[ 39%] Linking CXX shared library ../lib/libORB_SLAM3.so
/usr/bin/ld: cannot find -lepoxy::epoxy: No such file or directory
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/ORB_SLAM3.dir/build.make:605: ../lib/libORB_SLAM3.so] Error 1
make[1]: *** [CMakeFiles/Makefile2:192: CMakeFiles/ORB_SLAM3.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

已通过sudo apt-get install libepoxy-dev安装epoxy库，但CMake仍无法识别；添加find_package(epoxy REQUIRED)后编译报错：

CMake Error at CMakeLists.txt:46 (find_package):
  By not providing "Findepoxy.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "epoxy", but
  CMake did not find one.

  Could not find a package configuration file provided by "epoxy" with any of
  the following names:

    epoxyConfig.cmake
    epoxy-config.cmake

  Add the installation prefix of "epoxy" to CMAKE_PREFIX_PATH or set
  "epoxy_DIR" to a directory containing one of the above files.  If "epoxy"
  provides a separate development package or SDK, be sure it has been
  installed.

同时伴随CMake警告：

CMake Warning (dev) at CMakeLists.txt:391 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "stereo_inertial_realsense_D435i_old" links to target "epoxy::epoxy"
  but the target was not found.  Perhaps a find_package() call is missing for
  an IMPORTED target, or an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

解决方案 #

方法1：手动创建epoxy的CMake导入目标 #

系统包安装的epoxy缺少CMake配置文件，可手动在ORB-SLAM3的CMakeLists.txt中添加导入规则：

1. 确认epoxy的安装路径：头文件通常在/usr/include/epoxy/，库文件在/usr/lib/x86_64-linux-gnu/libepoxy.so（64位系统）或/usr/lib/i386-linux-gnu/libepoxy.so（32位系统）。
2. 在CMakeLists.txt开头附近插入以下代码：

# 手动查找epoxy库和头文件
find_path(EPOXY_INCLUDE_DIR NAMES epoxy/gl.h)
find_library(EPOXY_LIBRARY NAMES epoxy)

# 创建epoxy::epoxy导入目标
add_library(epoxy::epoxy SHARED IMPORTED)
set_target_properties(epoxy::epoxy PROPERTIES
    IMPORTED_LOCATION "${EPOXY_LIBRARY}"
    INTERFACE_INCLUDE_DIRECTORIES "${EPOXY_INCLUDE_DIR}"
)

3. 注释掉之前添加的find_package(epoxy REQUIRED)，重新执行cmake ..和make -j$(nproc)。

方法2：替换链接目标为原始库名 #

修改ORB-SLAM3 CMakeLists.txt中所有链接epoxy::epoxy的代码，将其替换为epoxy：
例如把target_link_libraries(stereo_inertial_realsense_D435i_old epoxy::epoxy ...)改为target_link_libraries(stereo_inertial_realsense_D435i_old epoxy ...)，修改后重新编译。

方法3：从源码编译安装epoxy #

源码编译的epoxy会生成完整的CMake配置文件，步骤如下：

# 克隆源码
git clone https://github.com/anholt/libepoxy.git
cd libepoxy

# 编译安装
mkdir build && cd build
cmake ..
make -j$(nproc)
sudo make install

完成后重新编译ORB-SLAM3，find_package(epoxy REQUIRED)即可正常识别库。

内容的提问来源于stack exchange，提问作者Ilia Nechaev