155 lines
5.5 KiB
CMake
155 lines
5.5 KiB
CMake
Getting started with CMake
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(These instructions apply to Unix-like systems, including Cygwin and Mac. To
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build using Visual Studio or some other IDE supported by CMake, most of the
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information below still applies)
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Always compile in a separate directory to the code. For example, if the
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code (eg, from Git) is at /home/curt/projects/flightgear, you might create
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/home/curt/projects/fgbuild. Change into the new directory, and run
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cmake ../flightger
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To generate standard Unix Makefiles in fgbuild.
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Probably you want to specify an install prefix:
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cmake ../flightgear -DCMAKE_INSTALL_PREFIX=/usr
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Note the install prefix is automatically searched for required libraries
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and header files, so if you install PLIB, OpenSceneGraph and SimGear to the
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same prefix, most configuration options are unnecessary.
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If for some reason you have a dependency (or several) at a different prefix,
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you can specify one or more via CMAKE_PREFIX_PATH:
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cmake ../flightgear -DCMAKE_PREFIX_PATH="/opt/local;/opt/fgfs"
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(note the use of semi-colons to specify multiple prefix paths)
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Standard prefixes are searched automatically (/usr, /usr/local, /opt/local)
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Most dependencies also expose an environment variable to specify their
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installation directory explicitly eg OSG_DIR or PLIBDIR. Any of the methods
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described above will work, but specifying an INSTALL_PREFIX or PREFIX_PATH is
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usually simpler.
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By default, we select a release build. To create a debug build, use
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cmake ../flightgear -DCMAKE_BUILD_TYPE=Debug
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(or MinSizeRel, or RelWithDbg)
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Debug builds will automatically use corresponding debug builds of required
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libraries, if they are available. For example you can install debug builds of
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SimGear and OpenSceneGraph, and a debug FlightGear build will use them.
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(Debug builds of libraries have the 'd' suffix by default - Release builds
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have no additional suffix)
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Note most IDE projects (eg Xcode and Visual Studio) support building all the
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build types from the same project, so you can omit the CMAKE_BUILD_TYPE option
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when running cmake, and simply pick the build configuration as normal in the
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IDE.
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It's common to have several build directories with different build
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configurations, eg
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/home/curt/projects/flightgear (the git clone)
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/home/curt/projects/fgdebug
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/home/curt/projects/fgrelease
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/home/curt/projects/fg-with-svn-osg
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To set an optional feature, do
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cmake ../flightgear -DFEATURE_NAME=ON
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(or 'OFF' to disable )
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To see the variables that can be configured / are currently defined, you can
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run one of the GUI front ends, or the following command:
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cmake ../flighgear -L
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Add 'A' to see all the options (including advanced options), or 'H' to see
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the help for each option (similar to running configure --help under autoconf):
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cmake ../flightgear -LH
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Build Targets
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For a Unix makefile build, 'make dist', 'make uninstall' and 'make test' are
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all available and should work as expected. 'make clean' is also as normal,
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but there is *no* 'make distclean' target. The equivalent is to completely
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remove your build directory, and start with a fresh one.
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Adding new files to the build
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Add source files to the SOURCES list, and headers to the HEADERS list. Note
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technically you only need to add source files, but omitting headers confuses
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project generation and distribution / packaging targets.
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For target conditional files, you can append to the SOURCES or HEADERS lists
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inside an if() test, for example:
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if(APPLE)
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list(APPEND SOURCES extraFile1.cxx extraFile2.cxx)
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endif()
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Setting include directories
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In any CMakeList.txt, you can do the following:
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include_directories(${PROJECT_SOURCE_DIR}/some/path)
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For example, this can be done in particular subdirectory, or at the project
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root, or an intermediate level.
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Setting target specific compile flags, includes or defines
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Use set_target_property(), for example
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set_target_property(fgfs PROPERTIES
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COMPILE_DEFINITIONS FOO BAR=1)
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You can set a property on an individual source file:
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set_property(SOURCE myfile.cxx PROPERTY COMPILE_FLAGS "-Wno-unsigned-compare")
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Detecting Features / Libraries
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For most standard libraries (Gtk, wxWidget, Python, GDAL, Qt, libXml, Boost),
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cmake provides a standard helper. To see the available modules, run:
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cmake --help-module-list
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In the root CMakeLists file, use a statement like:
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find_package(OpenGL REQUIRED)
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Each package helper sets various variables such aaa_FOUND, aaa_INCLUDE_DIR,
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and aaa_LIBRARY. Depending on the complexity of the package, these variables
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might have different names (eg, OPENSCENEGRAPH_LIBRARIES).
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If there's no standard helper for a library you need, find a similar one, copy
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it to CMakeModules/FindABC.cmake, and modify the code to fit. Generally this
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is pretty straightforward. The built-in modules reside in the Cmake 'share'
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directory, eg /usr/share/cmake/modules on Unix systems.
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Note libraries support by pkg-config can be handled directly, with no need
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to create a custom FindABC helper.
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Adding a new executable target
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add_executable(myexecutable ${SOURCES} ${HEADERS})
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target_link_libraries(myexecutable .... libraries ... )
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install(TARGETS myexecutable RUNTIME DESTINATION bin)
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(If the executable should not be installed, omit the final line above)
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If you add an additional line
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add_test(testname ${EXECUTABLE_OUTPUT_PATH}/myexecutable)
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Then running 'make test' will run your executable as a unit test. The
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executable should return either a success or failure result code.
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