关于cmake

最近在看blender的代码， 发现它用cmake做编译器，感觉真是相当不错。
用来做跨平台的编译管理真是方便。
原理嘛， 很简单，
cmake的配置文件->cmake->指定的编译器或是IDE的编译文件或是工程文件。
如cmake可以配置生成makefile，用于gcc一类的编译，
也可以生成sln文件， 用于微软的vs系列的编译。
当然也能生成xcode的编译文件，相当方便了。
下面就简单的介绍一下吧。

cmake的官方网站：

来由， 参见wiki,CMake 是為了解決出資的 專案下的 (ITK) 軟體的跨平台建構的需求而創造出來的.

当然了，现在应用相当广泛了。
至少blender, ogre都用cmake了。

cmake使用的文件叫 CMakeLists.txt， 每个要用到cmake控制的目录下都应该放一个。
当然，我们最终直接调用的就是代码根目录下的， CMakeLists.txt。
也就是我们所有的调用 都是从根目录下的CMakeLists.txt开始处理的。

推荐阅读：cmake/help/cmake_tutorial.html

下面注释一下这个页面里的CMakeLists.txt

cmake_minimum_required (VERSION 2.6)
project (Tutorial)

# The version number.
set (Tutorial_VERSION_MAJOR 1)
set (Tutorial_VERSION_MINOR 0)

# does this system provide the log and exp functions?
include (${CMAKE_ROOT}/Modules/CheckFunctionExists.cmake)

check_function_exists (log HAVE_LOG)
check_function_exists (exp HAVE_EXP)

# should we use our own math functions
option(USE_MYMATH
"Use tutorial provided math implementation" ON)

# configure a header file to pass some of the CMake settings
# to the source code
configure_file (
"${PROJECT_SOURCE_DIR}/TutorialConfig.h.in"
"${PROJECT_BINARY_DIR}/TutorialConfig.h"
)

# add the binary tree to the search path for include files
# so that we will find TutorialConfig.h
include_directories ("${PROJECT_BINARY_DIR}")

# add the MathFunctions library?
if (USE_MYMATH)
include_directories ("${PROJECT_SOURCE_DIR}/MathFunctions")
add_subdirectory (MathFunctions)
set (EXTRA_LIBS ${EXTRA_LIBS} MathFunctions)
endif (USE_MYMATH)

# add the executable
add_executable (Tutorial tutorial.cxx)
target_link_libraries (Tutorial  ${EXTRA_LIBS})

# add the install targets
install (TARGETS Tutorial DESTINATION bin)
install (FILES "${PROJECT_BINARY_DIR}/TutorialConfig.h"
DESTINATION include)

# does the application run
add_test (TutorialRuns Tutorial 25)

# does the usage message work?
add_test (TutorialUsage Tutorial)
set_tests_properties (TutorialUsage
PROPERTIES
PASS_REGULAR_EXPRESSION "Usage:.*number"
)


#define a macro to simplify adding tests
macro (do_test arg result)
add_test (TutorialComp${arg} Tutorial ${arg})
set_tests_properties (TutorialComp${arg}
PROPERTIES PASS_REGULAR_EXPRESSION ${result}
)
endmacro (do_test)

# do a bunch of result based tests
do_test (4 "4 is 2")
do_test (9 "9 is 3")
do_test (5 "5 is 2.236")
do_test (7 "7 is 2.645")
do_test (25 "25 is 5")
do_test (-25 "-25 is 0")
do_test (0.0001 "0.0001 is 0.01")