Make dart.pc relocatable (#1529)

Co-authored-by: Stefan Profanter <[email protected]>

CHANGELOG.md

@@ -83,6 +83,7 @@
   * Removed gccfilter: [#1464](https://github.com/dartsim/dart/pull/1464)
   * Allowed to set CMAKE_INSTALL_PREFIX on Windows: [#1478](https://github.com/dartsim/dart/pull/1478)
   * Enforced to use OpenSceneGraph 3.7.0 or greater on macOS Catalina: [#1479](https://github.com/dartsim/dart/pull/1479)
+  * Made `dart.pc` relocatable: [#1529](https://github.com/dartsim/dart/pull/1529)
 
 * Documentation
 

CMakeLists.txt

@@ -408,11 +408,17 @@ install(
 # Generate the DART pkg-config
 set(PC_CONFIG_IN ${CMAKE_SOURCE_DIR}/cmake/dart.pc.in)
 set(PC_CONFIG_OUT ${CMAKE_BINARY_DIR}/cmake/dart.pc)
+set(PC_CONFIG_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+file(RELATIVE_PATH
+  RELATIVE_PATH_TO_INSTALL_PREFIX
+  "${PC_CONFIG_INSTALL_DIR}"
+  "${CMAKE_INSTALL_PREFIX}"
+)
 if(DART_VERBOSE)
   message(STATUS ${PC_CONFIG_OUT})
 endif()
 configure_file(${PC_CONFIG_IN} ${PC_CONFIG_OUT} @ONLY)
-install(FILES ${PC_CONFIG_OUT} DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+install(FILES ${PC_CONFIG_OUT} DESTINATION ${PC_CONFIG_INSTALL_DIR})
 
 # Install a Catkin 'package.xml' file. This is required by REP-136.
 install(FILES package.xml DESTINATION

cmake/dart.pc.in

@@ -1,8 +1,8 @@
 # This file was generated by CMake for @PROJECT_NAME@
-prefix=@CMAKE_INSTALL_PREFIX@
+prefix=${pcfiledir}/@RELATIVE_PATH_TO_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${prefix}/lib
-includedir=${prefix}/include/dart
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@/dart
 
 Name: @PROJECT_NAME@
 Description: @DART_PKG_DESC@