GeographicLib
1.50.1
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Much (but not all!) of the useful functionality of GeographicLib is available via simple command line utilities. Interfaces to some of them are available via the web. See Utility programs for documentation on these.
In order to use GeographicLib from C++ code, you will need to
Building your code with cmake. In brief, the necessary steps are:
find_package (GeographicLib REQUIRED) add_executable (program source1.cpp source2.cpp) target_link_libraries (program ${GeographicLib_LIBRARIES})
mkdir BUILD cd BUILD cmake -G "Visual Studio 14" -A x64 \ -D CMAKE_PREFIX_PATH="C:/Program Files" \ -D CMAKE_INSTALL_PREFIX="C:/Program Files/testgeographic" \ ..Note that you almost always want to configure and build your code somewhere other than the source directory (in this case, we use the BUILD subdirectory). Also, on Windows, make sure that the version of Visual Studio (14 in the example above) architecture (x64 in the example above) is compatible with that used to build GeographicLib. In this example, it's not necessary to specify
CMAKE_PREFIX_PATH
, because C:/Program Files
is one of the system paths which is searched automatically.cmake --build . --config Release --target ALL_BUILDYou might also want to install your package (using "make install" or build the "INSTALL" target with the command above).
The most import step is the find_package command. The cmake documentation describes the locations searched by find_package (the appropriate rule for GeographicLib are those for "Config" mode lookups). In brief, the locations that are searched are (from least specific to most specific, i.e., in reverse order) are
C:/Program Files
and /usr/local
);CMAKE_PREFIX_PATH
(illustrated above);GeographicLib_DIR
(which is the directory under which GeographicLib is installed);GeographicLib_DIR
, which specifies the absolute path of the directory containing the configuration file geographiclib-config.cmake
(for debugging this may be the top-level build directory, as opposed to installation directory, for GeographicLib).Typically, specifying nothing or CMAKE_PREFIX_PATH
suffices. However the two GeographicLib_DIR
variables allow for a specific version to be chosen. On Windows systems (with Visual Studio), find_package will only find versions of GeographicLib built with the right version of the compiler. (If you used a non-cmake method of installing GeographicLib, you can try copying cmake/FindGeographicLib.cmake to somewhere in your CMAKE_MODULE_PATH
in order for find_package to work. However, this method has not been thoroughly tested.)
If GeographicLib is not found, check the values of GeographicLib_CONSIDERED_CONFIGS
and GeographicLib_CONSIDERED_VERSIONS
; these list the configuration files and corresponding versions which were considered by find_package.
If GeographicLib is found, then the following cmake variables are set:
GeographicLib_FOUND
= 1GeographicLib_VERSION
= 1.50.1GeographicLib_INCLUDE_DIRS
GeographicLib_LIBRARIES
= one of the following two:GeographicLib_SHARED_LIBRARIES
= GeographicLib_SHAREDGeographicLib_STATIC_LIBRARIES
= GeographicLib_STATICGeographicLib_LIBRARY_DIRS
GeographicLib_BINARY_DIRS
GEOGRAPHICLIB_DATA
= value of this compile-time parameterEither of GeographicLib_SHARED_LIBRARIES
or GeographicLib_STATIC_LIBRARIES
may be empty, if that version of the library is unavailable. If you require a specific version, SHARED or STATIC, of the library, add a COMPONENTS
clause to find_package, e.g.,
find_package (GeographicLib 1.34 REQUIRED COMPONENTS SHARED)
causes only packages which include the shared library to be found. If the package includes both versions of the library, then GeographicLib_LIBRARIES
is set to the shared version, unless you include
set (GeographicLib_USE_STATIC_LIBS ON)
before the find_package command. You can check whether GeographicLib_LIBRARIES
refers to the shared or static library with
get_target_property(_LIBTYPE ${GeographicLib_LIBRARIES} TYPE)
which results in _LIBTYPE
being set to SHARED_LIBRARY
or STATIC_LIBRARY
. On Windows, cmake takes care of linking to the release or debug version of the library as appropriate. (This assumes that the Release and Debug versions of the libraries were built and installed. This is true for the Windows binary installer for GeographicLib version 1.34 and later.)
g++ -c -g -O3 -I/usr/local/include testprogram.cppWith Visual Studio, specify the include directory in the IDE via, e.g.,
C/C++ -> General -> Additional Include Directories = C:\pkg-vc14-x64\GeographicLib\include
GEOGRAPHICLIB_SHARED_LIB=1
(or 0
), e.g., C/C++ -> Preprocessor -> Preprocessor Definitions = GEOGRAPHICLIB_SHARED_LIB=1This is only needed for Windows systems when both shared and static libraries have been installed. (If you configure your package with cmake, this definition is added automatically.)
g++ -g -o testprogram testprogram.o -L/usr/local/lib -lGeographicWith Visual Studio, you supply this information in the IDE via, e.g.,
Linker -> Input -> Additional Dependencies = Geographic-i.lib (for shared library) Linker -> Input -> Additional Dependencies = Geographic.lib (for static library) Linker -> General -> Additional Library Directories = C:\pkg-vc14-x64\Geographic\libNote that the library name is Geographic and not GeographicLib. For the Debug version of your program on Windows add "_d" to the library, e.g., Geographic_d-i.lib or Geographic_d.lib.
g++ -g -o testprogram testprogram.o -Wl,-rpath=/usr/local/lib \ -L/usr/local/lib -lGeographic(There are two other ways to specify the location of shared libraries at runtime: (1) define the environment variable
LD_LIBRARY_PATH
to be a colon-separated list of directories to search; (2) as root, specify /usr/local/lib as a directory searched by ldconfig(8).) On Windows, you need to ensure that Geographic.dll or Geographic_d.dll is in the same directory as your executable or else include the directory containing the dll in your PATH
.PKG_CONFIG_PATH
to include this directory. The compile and link steps under Linux would typically be g++ -c -g -O3 `pkg-config --cflags geographiclib` testprogram.cpp g++ -g -o testprogram testprogram.o `pkg-config --libs geographiclib`
Here is a very simple test code, which uses the Geodesic class:
This example is examples/example-Geodesic-small.cpp
. If you compile, link, and run it according to the instructions above, it should print out
5551.76 km
Here is a complete CMakeList.txt files you can use to build this test code using the installed library:
project (geodesictest) cmake_minimum_required (VERSION 3.1.0) find_package (GeographicLib REQUIRED) if (NOT MSVC) set (CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE) endif () add_executable (${PROJECT_NAME} example-Geodesic-small.cpp) target_link_libraries (${PROJECT_NAME} ${GeographicLib_LIBRARIES}) if (MSVC) get_target_property (_LIBTYPE ${GeographicLib_LIBRARIES} TYPE) if (_LIBTYPE STREQUAL "SHARED_LIBRARY") # On Windows systems, copy the shared library to build directory add_custom_command (TARGET ${PROJECT_NAME} POST_BUILD COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:${GeographicLib_LIBRARIES}> ${CMAKE_CFG_INTDIR} COMMENT "Copying shared library for GeographicLib") endif () endif ()
The next steps are:
Here's a list of some of the abbreviations used here with links to the corresponding Wikipedia articles: