CMake

Definition : What is CMake

• this is a tool or language (not compiler) that create commands of compiler based on what OS is and what kind of Generator (build system) we use.

Terms

[ .dll / .lib 언제 사용 ? ]

Install list of CMake dev env

Windows

1. install several software
   • Visual Studio 2022
     • Step 4 is important
   • CMake
   • Git
   • Doxygen
   • Python 3.8 or newer
2. install wsl : wsl --install
3. install package on linux (ubuntu)

    sudo apt-get update
    sudo apt-get upgrade
       
    # Mandatory
    sudo apt-get install gcc g++ gdb
    sudo apt-get install make cmake
    sudo apt-get install git
    sudo apt-get install doxygen
    sudo apt-get install python3 python3-pip
       
    # Optional
    sudo apt-get install lcov gcovr
    sudo apt-get install ccache
    sudo apt-get install cppcheck
    sudo apt-get install llvm clang-format clang-tidy
    sudo apt-get install curl zip unzip tar
    sudo apt-get install graphviz
   

4. install several extentions of vscode
   • C/C++ Extension Pack
   • Coding Tools extension Pack
   • WSL
5. set global setting on VScode (User tab) optional

———————-

• separator

How to start

1. generate C/C++ config files (vscode - command pallate)

    > C/C++ Config: Generate C++ config Files
   

2. open vscode in workspace directory and turn it into wsl workspace

    > wsl: reopen folder in wsl
   

3. move to exact folder where you want to work in

    ctrl+k ctrl+o # open folder
   

Build after coding

```
0.) Create Source and CMakeFile
1.) mkdir build
2.) cd build
3.) cmake ..   -  Generting the Build Files / Configure the Project
4.) cmake --build .
5.) ./Executable
```

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• separator

[ 실행파일 더하기 - Basic (project / add_executable) ]

cmake_minimum_required(VERSION 3.22)

#       projectName         projectVersion  projectLanguage (CXX stands for C++)
#           v                   v               v
project(CppProjectTemplate  VERSION 1.0.0   LANGUAGES C CXX)

#          User defined name
#                  v
add_executable(Executable main.cc)

[ 변수 추가 - set ]

• set(변수명 변수값) or set(변수명 “변수값”) -> 선호에 따라서

set(LIBRARY_SOURCES
    my_lib.cc)
set(LIBRARY_HEADERS
    my_lib.h)

    or

set(LIBRARY_SOURCES
    "my_lib.cc")
set(LIBRARY_HEADERS
    "my_lib.h")

[ os 환경변수 (외부환경변수) 사용 ]

• set(CMAKE변수명 $ENV{컴퓨터환경변수})
• bring os env variable in cmake. and then use it as a local variable

[ local 라이브러리 추가 - add library ]

• 이건 하나의 CMakeList.txt로 다 해결하려고 할때.
• prerequisites
  • we have to know c++ syntax in advance.
  • create header file
  • include the header file in target source file

set(EXECUTABLE_NAME Executable)
set(LIBRARY_NAME Library)

add_library(${LIBRARY_NAME} my_lib.cc)                      # library 파일들 리스트업
add_executable(${EXECUTABLE_NAME} main.cc)                  # execuatable 하게 만들 파일 targeting
target_link_libraries(${EXECUTABLE_NAME} ${LIBRARY_NAME})   # library하고 target파일을 연결관계 정의 

[ local 라이브러리 추가 2 ]

• 폴더 구조를 만들고, library 를 위한 코드들이 다른 공간으로 분리되어있을 때,
• header 파일을 추가하고싶을때, 사용

# - root
#     |-- app
#     |    |-- main.cc
#     |    |-- CMakeList.txt : 
#                   add_executable(${EXECUTABLE_NAME} "main.cc")
#                   target_link_libraries(${EXECUTABLE_NAME} PUBLIC ${LIBRARY_NAME})
#     |-- src
#          |-- CMakeList.txt : add_subdirectory(my_lib)
#          |-- my_lib
#                |-- CMakeList.txt : add_library / target_include_directories 사용 ----------
#     |-- CMakeList.txt                                                                     |
#                   cmake_minimum_required(VERSION 3.22)                                    |
#                   project(CppProjectTemplate VERSION 1.0.0 LANGUAGES C CXX)               |
#                   set(EXECUTABLE_NAME Executable)                                         |
#                   set(LIBRARY_NAME Library)                                               |
#                   add_subdirectory(src)                                                   |
#                   add_subdirectory(app)                                                   |
#                                   ---------------------------------------------------------
#                                   |
set(LIBRARY_SOURCES
    my_lib.cc)
set(LIBRARY_HEADERS
    my_lib.h)

add_library(${LIBRARY_NAME} STATIC
    ${LIBRARY_SOURCES}
    ${LIBRARY_HEADERS})
# Include dir to header files
# This does not have to be set, to be able to compile the program
# However, for MSVC builds this is needed, to have the headers listed in VS.
target_include_directories(${LIBRARY_NAME} PUBLIC 
    "./")

[ Debug / release 지정하는법 ]

• First off Debug/Release are called configurations in cmake (nitpick). If you are using a single configuration generator (Ninja/Unix-Makefiles) you must specify the CMAKE_BUILD_TYPE.

• Like this:

# Configure the build
cmake -S . -B build/ -D CMAKE_BUILD_TYPE=Debug

# Actually build the binaries
cmake --build build/

# Configure a release build
cmake -S . -B build/ -D CMAKE_BUILD_TYPE=Release

# Build release binaries
cmake --build build/
For multi-configuration generators it's slightly different (Ninja Multi-Config, Visual Studio)

# Configure the build
cmake -S . -B build

# Build debug binaries
cmake --build build --config Debug

# Build release binaries
cmake --build build --config Release

• If you are wondering why this is necessary it’s because cmake isn’t a build system. It’s a meta-build system (IE a build system that build’s build systems). This is basically the result of handling build systems that support multiple-configurations in 1 build. If you’d like a deeper understanding I’d suggest reading a bit about cmake in Craig Scott’s book “Professional CMake: A Practical Guide

[ External library 사용 - Imath]

1. Imath build 먼저
   • Imath install Guide- Build from Source
2. CMakeList.txt 에 아래의 conditions 들 추가
   1. set Imath_DIR to ImathConfig.cmake directory.
   2. put include directory in target_include_directories() function
   3. put .lib file path in target_link_libraries() function to link in between source code and libraries.

   
    ...
   
    set(Imath_ROOT ...)
    set(Imath_LIB ${Imath_ROOT}/lib/Imath-3_1.lib)
    set(Imath_DIR ${Imath_ROOT}/lib/cmake/Imath)
    set(Imath_INCLUDE_DIR ${Imath_ROOT}/include/Imath)
       
    find_package(Katana PATHS "${KATANA_ROOT}/plugin_apis/cmake" REQUIRED)
    find_package(Imath REQUIRED)
       
    add_library(
                ${LIBRARY_NAME}
                MODULE
                code.cpp
    )
       
    target_include_directories(
        ${LIBRARY_NAME}
        PUBLIC
        ${Imath_INCLUDE_DIR}
    )
       
    target_link_libraries(${LIBRARY_NAME}
        PRIVATE
        Katana::FnGeolibPluginApis::Shared
        ${Imath_LIB}
    )
    set_target_properties(${LIBRARY_NAME} PROPERTIES PREFIX "")