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