fg用cmake编译时出现错误

Simgear已经编译好了，但是当用Cmake编译flightgear的时候却出现：CMake Error at CMakeModules/FindSimGear.cmake:83 (message):

Cannot find SimGear includes! (Forgot 'make install' for SimGear?) Compile

& INSTALL SimGear before configuring FlightGear. When using non-standard

locations, use 'SIMGEAR_DIR' to configure the SimGear location.

Call Stack (most recent call first):

CMakeLists.txt:234 (find_package)
于是，我在SIMGEAR_INCLUDE_DIR设置了simgear的路径，但是还是不对。请大家帮忙