1 Getting started with CMake
3 [Windows instructions at the end of this document]
5 (These instructions apply to Unix-like systems, including Cygwin and Mac. To
6 build using Visual Studio or some other IDE supported by CMake, most of the
7 information below still applies)
9 Always compile in a separate directory to the code. For example, if the
10 code (eg, from Git) is at /home/curt/projects/flightgear, you might create
11 /home/curt/projects/fgbuild. Change into the new directory, and run
15 To generate standard Unix Makefiles in fgbuild.
17 Probably you want to specify an install prefix:
19 cmake ../flightgear -DCMAKE_INSTALL_PREFIX=/usr
21 Note the install prefix is automatically searched for required libraries
22 and header files, so if you install PLIB, OpenSceneGraph and SimGear to the
23 same prefix, most configuration options are unnecessary.
25 If for some reason you have a dependency (or several) at a different prefix,
26 you can specify one or more via CMAKE_PREFIX_PATH:
28 cmake ../flightgear -DCMAKE_PREFIX_PATH="/opt/local;/opt/fgfs"
30 (note the use of semi-colons to specify multiple prefix paths)
32 Standard prefixes are searched automatically (/usr, /usr/local, /opt/local)
34 Most dependencies also expose an environment variable to specify their
35 installation directory explicitly eg OSG_DIR or PLIBDIR. Any of the methods
36 described above will work, but specifying an INSTALL_PREFIX or PREFIX_PATH is
39 By default, we select a release build. To create a debug build, use
41 cmake ../flightgear -DCMAKE_BUILD_TYPE=Debug
43 (or MinSizeRel, or RelWithDbg)
45 Debug builds will automatically use corresponding debug builds of required
46 libraries, if they are available. For example you can install debug builds of
47 SimGear and OpenSceneGraph, and a debug FlightGear build will use them.
49 (Debug builds of libraries have the 'd' suffix by default - Release builds
50 have no additional suffix)
52 Note most IDE projects (eg Xcode and Visual Studio) support building all the
53 build types from the same project, so you can omit the CMAKE_BUILD_TYPE option
54 when running cmake, and simply pick the build configuration as normal in the
57 It's common to have several build directories with different build
60 /home/curt/projects/flightgear (the git clone)
61 /home/curt/projects/fgdebug
62 /home/curt/projects/fgrelease
63 /home/curt/projects/fg-with-svn-osg
65 To set an optional feature, do
67 cmake ../flightgear -DFEATURE_NAME=ON
69 (or 'OFF' to disable )
71 To see the variables that can be configured / are currently defined, you can
72 run one of the GUI front ends, or the following command:
76 Add 'A' to see all the options (including advanced options), or 'H' to see
77 the help for each option (similar to running configure --help under autoconf):
79 cmake ../flightgear -LH
83 For a Unix makefile build, 'make dist', 'make uninstall' and 'make test' are
84 all available and should work as expected. 'make clean' is also as normal,
85 but there is *no* 'make distclean' target. The equivalent is to completely
86 remove your build directory, and start with a fresh one.
88 Adding new files to the build
90 Add source files to the SOURCES list, and headers to the HEADERS list. Note
91 technically you only need to add source files, but omitting headers confuses
92 project generation and distribution / packaging targets.
94 For target conditional files, you can append to the SOURCES or HEADERS lists
95 inside an if() test, for example:
98 list(APPEND SOURCES extraFile1.cxx extraFile2.cxx)
101 Setting include directories
103 In any CMakeList.txt, you can do the following:
105 include_directories(${PROJECT_SOURCE_DIR}/some/path)
107 For example, this can be done in particular subdirectory, or at the project
108 root, or an intermediate level.
110 Setting target specific compile flags, includes or defines
112 Use set_target_property(), for example
114 set_target_property(fgfs PROPERTIES
115 COMPILE_DEFINITIONS FOO BAR=1)
117 You can set a property on an individual source file:
119 set_property(SOURCE myfile.cxx PROPERTY COMPILE_FLAGS "-Wno-unsigned-compare")
121 Detecting Features / Libraries
123 For most standard libraries (Gtk, wxWidget, Python, GDAL, Qt, libXml, Boost),
124 cmake provides a standard helper. To see the available modules, run:
126 cmake --help-module-list
128 In the root CMakeLists file, use a statement like:
130 find_package(OpenGL REQUIRED)
132 Each package helper sets various variables such aaa_FOUND, aaa_INCLUDE_DIR,
133 and aaa_LIBRARY. Depending on the complexity of the package, these variables
134 might have different names (eg, OPENSCENEGRAPH_LIBRARIES).
136 If there's no standard helper for a library you need, find a similar one, copy
137 it to CMakeModules/FindABC.cmake, and modify the code to fit. Generally this
138 is pretty straightforward. The built-in modules reside in the Cmake 'share'
139 directory, eg /usr/share/cmake/modules on Unix systems.
141 Note libraries support by pkg-config can be handled directly, with no need
142 to create a custom FindABC helper.
144 Adding a new executable target
146 add_executable(myexecutable ${SOURCES} ${HEADERS})
147 target_link_libraries(myexecutable .... libraries ... )
148 install(TARGETS myexecutable RUNTIME DESTINATION bin)
150 (If the executable should not be installed, omit the final line above)
152 If you add an additional line
154 add_test(testname ${EXECUTABLE_OUTPUT_PATH}/myexecutable)
156 Then running 'make test' will run your executable as a unit test. The
157 executable should return either a success or failure result code.
161 SPECIAL INSTRUCTIONS TO BUILD UNDER WINDOWS WITH VISUAL STUDIO
162 ==============================================================
164 On Windows, assumptions on the directory structure are made to automate the discovery of dependencies.
165 This recommended directory structure is described below:
167 ${MSVC_3RDPARTY_ROOT} /
168 3rdParty / ( includes plib, fltk, zlib, libpng, libjpeg, libtiff, freetype, libsvn, gdal, ...
172 3rdParty.x64 / ( 64 bit version )
177 msvc100 / ( for VS2010 32 bits, or msvc90, msvc90-64 or msvc100-64 for VS2008 32, VS2008 64 and VS2010 64 )
178 OpenSceneGraph / ( OSG CMake install
186 If you do not use the recommended structure you will need to enter paths by hand. Source and build directories can be located anywhere.
188 The suggested inputs to cmake are :
189 MSVC_3RDPARTY_ROOT : location of the above directory structure
190 CMAKE_INSTALL_PREFIX : ${MSVC_3RDPARTY_ROOT}/install/msvc100/FlightGear (or any variation for the compiler version described above )
193 1. Set up a work directory as described above.
195 2. Open the Cmake gui.
197 3. Set "Where is the source code" to wherever you put the FlightGear sources (from the released tarball or the git repository).
199 4. Set "Where to build the binaries" to an empty directory.
201 5. Press the "Configure" button. The first time that the project is configured, Cmake will bring up a window asking which compiler you wish to use. Normally just accept Cmakes suggestion, and press Finish. Cmake will now do a check on your system and will produce a preliminary build configuration.
203 6. Cmake adds new configuration variables in red. Some have a value ending with -NOTFOUND. These variables should receive your attention. Some errors will prevent FlightGear to build and others will simply invalidate some options without provoking build errors. First check the MSVC_3RDPARTY_ROOT variable. If it is not set, chances are that there will be a lot of -NOTFOUND errors. Instead of trying to fix every error individually, set that variable and press the "Configure" button again.
205 7. Also check the lines with a checkbox. These are build options and may impact the feature set of the built program.
207 8. Change the CMAKE_INSTALL_PREFIX to ${MSVC_3RDPARTY_ROOT}/install/msvc100/FlightGear because C:\Program Files is likely unwritable to ordinary Windows users and will integrate better with the above directory structure (this is mandatory for SimGear if you don't want to solve errors by hand).
209 10. Repeat the process until the "Generate" button is enabled.
211 11. Press the "Generate" button.
213 12. Start Visual Studio 2010 and load the FlightGear solution (FlightGear.sln) located in "Where to build the binaries" (point 4.)
215 13. Choose the "Release" build in the VS2010 "Generation" toolbar
217 14. Generate the solution.
219 15. If there are build errors, return to Cmake, clear remaining errors, "Configure" and "Generate"
221 16. When Visual Studio is able to build everything without errors, build the INSTALL project to put the product files in ${CMAKE_INSTALL_PREFIX}
225 PS: When updating the source from git, it is usually unnecessary to restart Cmake as the solution is able to reconfigure itself when Cmake files are changed. Simply rebuild the solution from Visual Studio and accept the reload of updated projects. It also possible to edit CMakeList.txt files directly in Visual Studio as they also appear in the solution, and projects will be reconfigured on the next generation. To change build options or directory path, it is mandatory to use the Cmake Gui. In case of problems, locate the CMakeCache.txt in "Where to build the binaries
\94 directory and delete it to reconfigure from scratch or use the menu item File->Delete Cache.