[SOLVED] Location of native libraries

Troubleshooting physics
1

Hi,

I’m setting my first steps into multiplayer game development. At this moment I have a game client and game server running.

The server is running in a docker container, and I start the server without jme, so no class that extends from SimpleApplication.
This means that for example the extraction of native libraries isn’t included when starting the application.

I added this command in docker before starting the application:
java -cp jme3-core-3.2.2-stable.jar:jme3-desktop-3.2.2-stable.jar:jme3-bullet-native-3.2.2-stable.jar com.jme3.system.ExtractNativeLibraries Linux64 ../bin

And I see that indeed the libbulletjme.so file is extracted in the bin folder, next to the 2 startup scripts generated by gradle.

However, when I am starting the server, I get this error::

Exception in thread "main" java.lang.UnsatisfiedLinkError: com.jme3.bullet.PhysicsSpace.createPhysicsSpace(FFFFFFIZ)J
	at com.jme3.bullet.PhysicsSpace.createPhysicsSpace(Native Method)
	at com.jme3.bullet.PhysicsSpace.create(PhysicsSpace.java:243)
	at com.jme3.bullet.PhysicsSpace.<init>(PhysicsSpace.java:236)
	at org.chimpstack.jme3.es.bullet.BulletSystem.initialize(BulletSystem.java:104)
	at com.simsilica.sim.AbstractGameSystem.initialize(AbstractGameSystem.java:75)
	at com.simsilica.sim.GameSystemManager.initialize(GameSystemManager.java:114)
	at org.chimpstack.wof.server.GameServer.<init>(GameServer.java:96)
	at org.chimpstack.wof.server.Main.main(Main.java:50)

both jme3-bullet and jme3-bullet-native are on the classpath. Am I missing some other native libraries? Are the native files in the correct directory?

for completeness the folder structure of the unpacked .tar file generated by the gradle build task:

wof-server
. bin
… wof-server
… wof-server.bat
… libbulletjme.so
. lib
… skipped other libraries
… jme3-bullet-3.2.2-stable.jar
… jme3-bullet-native-3.2.2-stable.jar
… jme3-core-3.2.2-stable.jar
… jme3-desktop-3.2.2-stable.jar
… jme3-es-bullet-0.1.0.jar
… jme3-networking-3.2.1-stable.jar
… jme3-terrain-3.2.2-stable.jar

The command is launched inside the bin directory, the bin directory is the working dir.

I tried:

  • setting the LD_LIBRARY_PATH="/app/wof-server/bin" variable
  • adding -Djava.library.path="/app/wof-server/bin" to the startup script
    still no luck
2

I do something quite similar with my server, although I extract the libraries from the jars at runtime. You need to explicitly load them via the usual System.loadLibrary() means - the system won’t automatically find and load them.

1 Like
3

aha! thanks for the tip, I’ll try that!

4

No problem! If you have more trouble with it let me know and I’ll look up how my code is doing it and provide you with some snippets.

1 Like
5

yep, that does seem to do the trick!

tested it quickly:

static {
    System.load(System.getProperty("user.dir") + "/libbulletjme.so");
}

and the application starts up without throwing an error.

edit: for further reference, this is probably the best solution:

static {
    NativeLibraryLoader.loadNativeLibrary("bulletjme", true);
}

This way, I don’t even have to do the extraction of the libs myself!

3 Likes
6

It’s also not that hard to detect the OS and auto-extract the right native lib from the jars. :grinning: