使用Irrlicht为CMake项目构建错误LNK1104

Question

我目前正在用Visual Studio 2019做一个学校项目，我们面临着一个问题：

LINK : fatal error LNK1104: cannot open file 'Irrlicht.lib'

只有当我们已经编译了我们的CMake文件时，错误才会出现，这是它第一次工作。

我的CMakeLists.txt：

cmake_minimum_required(VERSION 3.9)
project(IndieCMAKE)

set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})
set(CMAKE_CXX_STANDARD 11)
set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)

find_package(Irrlicht)

link_libraries(Irrlicht)

INCLUDE_DIRECTORIES(
        "/usr/include/irrlicht"
        "./include"
${PROJECT_SOURCE_DIR}/include
)
include_directories(inc)

add_executable(IndieCMAKE
 ./main.cpp)

这是我的FindIrrlicht.cmake文件：

    IF (NOT Irrlicht_INCLUDE_DIRS OR NOT Irrlicht_LIBRARIES)
  FIND_PATH(Irrlicht_INCLUDE_DIRS
    NAMES
      irrlicht.h
    PATHS
      /usr/include/irrlicht/        # Default Fedora28 system include path
      /usr/local/include/irrlicht/  # Default Fedora28 local include path
      ${CMAKE_MODULE_PATH}/include/ # Expected to contain the path to this file for Windows10
      ${Irrlicht_DIR}/include/      # Irrlicht root directory (if provided)
  )

  IF (MSVC)     # Windows
    SET(CMAKE_FIND_LIBRARY_PREFIXES "")
    SET(CMAKE_FIND_LIBRARY_SUFFIXES ".lib")
  ELSE (MSVC)   # Linux
    SET(CMAKE_FIND_LIBRARY_PREFIXES "lib")
    SET(CMAKE_FIND_LIBRARY_SUFFIXES ".so")
  ENDIF(MSVC)

  FIND_LIBRARY(Irrlicht_LIBRARIES
    NAMES
      Irrlicht
    PATHS
      /usr/lib64             # Default Fedora28 library path
      /usr/lib/                     # Some more Linux library path
      /usr/lib/x86_64-linux-gnu/    # Some more Linux library path
      /usr/local/lib/               # Some more Linux library path
      /usr/local/lib64/             # Some more Linux library path
      ${CMAKE_MODULE_PATH}/         # Expected to contain the path to this file for Windows10
      ${Irrlicht_DIR}/              # Irrlicht root directory (if provided)
  )
ENDIF (NOT Irrlicht_INCLUDE_DIRS OR NOT Irrlicht_LIBRARIES)

IF (Irrlicht_INCLUDE_DIRS AND Irrlicht_LIBRARIES)
  SET(Irrlicht_FOUND TRUE)
ELSE (Irrlicht_INCLUDE_DIRS AND Irrlicht_LIBRARIES)
  SET(Irrlicht_FOUND FALSE)
ENDIF (Irrlicht_INCLUDE_DIRS AND Irrlicht_LIBRARIES)

IF (Irrlicht_FIND_REQUIRED AND NOT Irrlicht_FOUND)
  MESSAGE(FATAL_ERROR
    "  Irrlicht not found.\n"
    "      Windows: Fill CMake variable CMAKE_MODULE_PATH to the provided directory.\n"
    "      Linux: Install Irrlicht using your package manager ($> sudo dnf install irrlicht-devel).\n"
  )
ENDIF (Irrlicht_FIND_REQUIRED AND NOT Irrlicht_FOUND)

以下是我的CMake图形用户界面变量：

​

​

Answer 1

如果您使用的是CMake Find Module，例如FindIrrlicht.cmake文件，find_package(Irrlicht)命令应该会为您填充一些Irrlicht_* CMake变量。假设find_package()确实正确地找到了包组件，您可以在CMake文件中使用这些Irrlicht_*变量来指定CMake应该在何处查找Irrlicht包头和库。

类似下面的CMake文件应该可以工作：

cmake_minimum_required(VERSION 3.9)
project(IndieCMAKE)

set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})
set(CMAKE_CXX_STANDARD 11)
set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)

# Use REQUIRED here, to ensure CMake finds the package before continuing.
find_package(Irrlicht REQUIRED)

# Don't use this command. It's old, and the syntax didn't work, in your case.
#link_libraries(Irrlicht)

# Specify your directories that contain headers, including the Irrlicht headers.
include_directories(
    ${Irrlicht_INCLUDE_DIRS}
)

# Define your executable target.
add_executable(IndieCMAKE
    main.cpp
)

# Link the Irrlicht library to your executable target.
target_link_libraries(IndieCMAKE PRIVATE ${Irrlicht_LIBRARIES})