Suggested changes to WIKI-Page Building FlightGear - Debian

[danielHL]

Hi everyone,

I just spent two days building Flightgear GIT on Debian. I followed the great wiki guide "Building FlightGear - Debian". Some problems came up, but my experiences gained from several LinuxFromScratch-runs have finally paid out

I would suggest the following changes to the guide:

OpenSceneGraph:
FG GIT only (currently?) only builds against OpenSceneGraph-3.2.0, not against newer releases. Errors would be linker problems concerning libosg when building FG.

SimGear and FlightGear:
I had to add "-D CMAKE_PREFIX_PATH="$FG_INSTALL_DIR" to the cmake options to avoid various linker problems. Otherwise, the script couldn't find the self-built libOSG and libsimgear but defaulted to my older system installation in /usr/lib etc. Seems useful to add this if you want to keep the FlightGear-version of your distribution installed aswell.
e.g.:
cmake -D CMAKE_INSTALL_PREFIX="$FG_INSTALL_DIR" -D CMAKE_PREFIX_PATH="$FG_INSTALL_DIR" $FG_SRC_DIR/simgear.git

Atlas:
Had to change the ./configure-Line to
./configure --prefix=$FG_INSTALL_DIR --with-fgbase=$FG_INSTALL_DIR/data --with-plib=$FG_INSTALL_DIR --with-simgear=$FG_INSTALL_DIR --with-osg=$FG_INSTALL_DIR --enable-simgear-shared

Errors with the wiki-suggested line were ld defaulting to system versions of plib, libosg and simgear. Also, the linker somehow expects static libraries if not told otherwise (--enable-simgear-shared).

I don't know if this happens to all debian users, but i only got FG to build correctly using these altered commands. Can someone verify this, please? Who do I need to inform to get these changes on the fg-wiki?

CU
Daniel

[Hooray]

Hi & welcome, and thanks for pointing out such problems.
Regarding updating the article, please feel free to do it yourself, it's a wiki after all - you only need to register an account, you can add your comments next to the other instructions for now.

[sanhozay]

FG GIT only (currently?) only builds against OpenSceneGraph-3.2.0, not against newer releases. Errors would be linker problems concerning libosg when building FG.

Did you mean older here? I had a similar issue with Xubuntu 13.10 where I had to download and compile OSG because the packaged version was too old.

SimGear and FlightGear:
I had to add "-D CMAKE_PREFIX_PATH="$FG_INSTALL_DIR" to the cmake options to avoid various linker problems. Otherwise, the script couldn't find the self-built libOSG and libsimgear but defaulted to my older system installation in /usr/lib etc. Seems useful to add this if you want to keep the FlightGear-version of your distribution installed aswell.
e.g.:
cmake -D CMAKE_INSTALL_PREFIX="$FG_INSTALL_DIR" -D CMAKE_PREFIX_PATH="$FG_INSTALL_DIR" $FG_SRC_DIR/simgear.git

Looking at my little build script, I think I ran into a similar issue but solved it with CMAKE_INSTALL_PREFIX. Additionally, I had to define CMAKE_LIBRARY_PATH to pick up the compiled OSG library.

Did you have to set LD_LIBRARY_PATH to pick up OSG at runtime?

You might want to use "-D CMAKE_BUILD_TYPE=Release" too, so that you get the right optimizer flags.

[curVV]

Did you have to set LD_LIBRARY_PATH to pick up OSG at runtime?

I had to. I thought FG automagically looked in FG_install_dir/lib for libraries.

[Hooray]

only if -DCMAKE_INSTALL_PREFIX is set accordingly for all dependencies (especially OSG, SG & FG)

[curVV]

What's the difference between these two:

-DCMAKE_INSTALL_PREFIX
and
-DCMAKE_PREFIX_PATH

I set both to install dir building OSG, SG and FG but still it complained about not finding libosgText.so.100... until I set LD_LIBRARY_PATH.