Let citygmlConfig.cmake also define include dirs.

With this a library user can just use
target_link_libraries(citygml::citygml) and the
include directories are set up automatically.

CMakeLists.txt

@@ -87,12 +87,14 @@ SET(OUTPUT_LIBDIR ${PROJECT_BINARY_DIR}/lib)
 MAKE_DIRECTORY(${OUTPUT_LIBDIR})
 SET(LIBRARY_OUTPUT_PATH ${OUTPUT_LIBDIR})
 
+if(NOT DEFINED INCLUDE_INSTALL_DIR)
+    set(INCLUDE_INSTALL_DIR "include")
+endif(NOT DEFINED INCLUDE_INSTALL_DIR)
+set(INCLUDE_INSTALL_CITYGML_DIR "${CMAKE_INSTALL_PREFIX}/${INCLUDE_INSTALL_DIR}/citygml")
+
 if(NOT DEFINED DATA_INSTALL_DIR)
     set(DATA_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/share")
 endif(NOT DEFINED DATA_INSTALL_DIR)
-if(NOT DEFINED INCLUDE_INSTALL_DIR)
-    set(INCLUDE_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/include/citygml")
-endif(NOT DEFINED INCLUDE_INSTALL_DIR)
 if(NOT DEFINED MAN_INSTALL_DIR)
     set(MAN_INSTALL_DIR "${DATA_INSTALL_DIR}/man")
 endif(NOT DEFINED MAN_INSTALL_DIR)

sources/CMakeLists.txt

@@ -250,8 +250,9 @@ set_target_properties( ${target} PROPERTIES
 )
 
 if(NOT DEFINED INCLUDE_INSTALL_DIR)
-    set(INCLUDE_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/include/citygml")
+    set(INCLUDE_INSTALL_DIR "include")
 endif(NOT DEFINED INCLUDE_INSTALL_DIR)
+set(INCLUDE_INSTALL_CITYGML_DIR "${CMAKE_INSTALL_PREFIX}/${INCLUDE_INSTALL_DIR}/citygml")
 
 if(WIN32)
   set(CONFIG_INSTALL_DIR "cmake")
@@ -265,6 +266,7 @@ INSTALL(
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    INCLUDES DESTINATION ${INCLUDE_INSTALL_DIR}
     COMPONENT "runtime"
 )
 INSTALL(
@@ -294,15 +296,15 @@ INSTALL(
 INSTALL(
     FILES
       ${PUBLIC_HEADER}
-    DESTINATION  ${INCLUDE_INSTALL_DIR}
+    DESTINATION  ${INCLUDE_INSTALL_CITYGML_DIR}
     COMPONENT "development"
 )
 
 INSTALL(
     FILES
       ${EXPORT_HEADER_FILE_NAME}
     DESTINATION
-      ${INCLUDE_INSTALL_DIR}
+      ${INCLUDE_INSTALL_CITYGML_DIR}
     COMPONENT "development"
 )