How does JOGL search for OpenGL libraries? - java

I'm writing a desktop app using JOGL, and deploying on Win/Mac/Linux. On Linux we find that the OpenGL libraries installed are not always up to the job, and we need to have the capability of switching our own software emulation OpenGL in. Naturally we expected that we could place out libraries after /usr/lib or before /usr/lib to favour ours or the default.
It turns out that ours are picked up preferentially by JOGL. Does anyone know if the JOGl libraries do special processing looking for libGL etc, favouring perhaps a later version over an earlier? Any information welcome.

I assume that the Java side of JOGL uses JNI (Java Native Interface) to interface with the native libraries. JNI uses ths Java system variable java.library.path to find native libraries. You could set it on the command line using the -D switch when running your Java app:
java -Djava.library.path=/some/path mypackage.MyProgram
It could also be that the native system doesn't pick up the right OpenGL libraries itself. On Linux, you can set the environment variable LD_LIBRARY_PATH to specify where Linux should look for shared libraries. This page explains more (see section 3.3.1).
Note that you can get the source code of JOGL on the JOGL homepage, so if you really want to know, you could download it and start digging into it.
(why is there a stupid limitation "new users can only post one hyperlink"????)

Related

Compiling/packaging java programs into standalone executables?

I would like to deploy a java (or javafx program) which is usable even on a system that doesn't have JRE.
This question has been asked and answered:
How can I convert my Java program to an .exe file?
Compiling a java program into an executable
But those 2 questions are over 10 years old, and I'm wondering if there are any new/better options as of 2022.
There are some options you could choose from:
Bundle your JRE in your package
Eclipse does this for example. The put a JRE in the downloaded ZIP-File
The rise of the native images
Some projects start to do native java-executables. One is Quarkus. But the don't support JavaFx. Base technology for that is GraalVM
Spring is also starting native images: Spring-Native
Here is an example of a java-fx native image: Java-FX Native Demo
The tools to compile a JavaFX program into a native exectable can be found here: https://github.com/gluonhq/gluonfx-maven-plugin
Depending on your needs it might be also interesting though to just package your program for each platform via jpackage. Maybe following this tutorial https://github.com/dlemmermann/JPackageScriptFX

how to export CUDA (jcuda) program

I just developped my first program with JCUDA (on eclipse) and i want to execute it on other machines that don't have the same nvidia-driver and compilers i used to develop it.
How can I export just the executable to another machine and execute it without recompiling the code ?
Any help will be appreciated
(Sorry, this may not fully answer your question if you expected a step-by-step-manual. I'll consider doing some experiments here, and maybe extend this answer or add the information on the website)
For the driver API, the CUDA version on the target system must at least be that of the corresponding JCuda version - otherwise, newer CUDA functions would simply not be supported.
Regarding the runtime libraries, quoting from the CUDA FAQ:
Q: What do I need to distribute my CUDA application?
Applications that use the driver API only need the CUDA driver library ("nvcuda.dll" under Windows), which is included as part of the standard NVIDIA driver install.
Applications that use the runtime API also require the runtime library ("cudart.dll" under Windows), which is included in the CUDA Toolkit. It is permissible to distribute this library with your application under the terms of the End User License Agreement included with the CUDA Toolkit.
So in doubt, you may include the "cudart.dll" that you used for compiling your application into the distribution package.
Newer versions of CUDA also support static linking against the runtime DLL, but this is not (yet?) done for the JCuda runtime library.

VHD Java library

I'm looking for a Java library that can open .vhd files. I wants to create a program that can navigate inside it. I also want it to be
cross-platform. I have googled for an library a while now but found nothing. I did only find an old unanswerd question here on stack overflow.
Can anyone help me?
Consider libguestfs. libguestfs is a C library, but it has a Java binding.
It claims to be cross-platform, working on Linux and Mac OS X, and "[s]ome virt tools have been ported to Windows". Check to see whether the features you need work on Windows.
libguestfs does support VHD images (under the format name vpc).
Obtaining libguestfs
The Java bindings, which contain the com.redhat.et.libguestfs package, are available as part of the source distribution tarball. This can be obtained from the libguestfs download page; select the latest version, currently 1.18.8.
Alternatively, a pre-compiled JAR might be available from the Maven repository.
Either way, on Windows you likely have to compile the native libguestfs library yourself.

How to fix an UnsatisfiedLinkError (Can't find dependent libraries) in a JNI project

I'm working on a Java project that uses the JNI. The JNI calls a custom library that I've written myself, let's say mylib.dll, and that depends on a 3rd party library, libsndfile-1.dll.
When I run my program it crashes with
java.lang.UnsatisfiedLinkError: C:\...path...\mylib.dll: Can't find dependent libraries.
I've searched this site (and others) and I've tried a number of fixes:
I ran dependency walker. DW gave a couple of warnings -- that two libraries required by libsndfile, MPR.DLL and SHLWAPI.DLL, had "unresolved imports" -- but the DW FAQ said that these warnings could be safely ignored.
I fixed the method names in mylib.dll, as suggested here. The method names had somehow gotten mangled by the compiler, but I added linker flags and the dll method names now match those in my jni header file exactly.
I put all of these DLLs in the same directory -- the same directory as the .jar that calls them -- to ensure that they're on the right PATH.
No dice.
Does anyone have any idea what's going on?
I'm doing my development in Visual Studio 2010 on a MacBook pro (via Parallels). I'm doing my testing in Windows XP on a toshiba laptop.
I'm pretty sure the classpath and the shared library search path have little to do with each other. According to The JNI Book (which admittedly is old), on Windows if you do not use the java.library.path system property, the DLL needs to be in the current working directory or in a directory listed in the Windows PATH environment variable.
Update:
Looks like Oracle has removed the PDF from its website. I've updated the link above to point to an instance of the PDF living at University of Texas - Arlington.
Also, you can also read Oracle's HTML version of the JNI Specification. That lives in the Java 8 section of the Java website and so hopefully will be around for a while.
Update 2:
At least in Java 8 (I haven't checked earlier versions) you can do:
java -XshowSettings:properties -version
to find the shared library search path. Look for the value of the java.library.path property in that output.
I want to inform this interesting case, after tried all the above method, the error is still there. The weird thing is it works on a Windows 7 computer, but on Windows XP it is not. Then I use dependency walker and found on the Windows XP there is no VC++ Runtime as my dll requirement. After installing VC++ Runtime package here it works like a charm. The thing that disturbed me is it keeps telling Can't find dependent libraries, while intuitively the JNI dependent dll is there, however it finally turns out the JNI dependent dll requires another dependent dl. I hope this helps.
You need to load your JNI library.
System.loadLibrary loads the DLL from the JVM path (JDK bin path).
If you want to load an explicit file with a path, use System.load()
See also: Difference between System.load() and System.loadLibrary in Java
If you load a 32 bit version of your dll with a 64 bit JRE you could have this issue. This was my case.
Please verify your library path is right or not. Of course, you can use following code to check your library path path:
System.out.println(System.getProperty("java.library.path"));
You can appoint the java.library.path when launching a Java application:
java -Djava.library.path=path ...
Did have identical problem with on XP machine when installing javacv and opencv in combination with Eclipse. It turned out that I was missing the following files:
msvcp100.dll
msvcr100.dll
Once these were installed, the project compiled and ran OK.
When calling System.loadLibrary(), the JVM will look on the java.library.path for your native library. However, if that native library declares any dependencies on other native libraries, then the operating system will be tasked with finding those native library dependencies.
Since the operating system has no concept of the java.library.path, it will not see any directories you place on the java.library.path. Instead, it will only search the directories on PATH environment variable of the operating system. This is totally fine if the native library dependency is an operating system native library because it will be found on the PATH. However, if the native library dependency is a native library that you or someone else created, then it will not be found on the PATH unless you place it there. This behavior is strange, unexpected, and not well documented, but it is documented in the OpenJDK issue tracker here. You can also find another StackOverflow answer reinforcing this explanation, here.
So, you have a couple of options. You could either load each native library in the correct dependency order using System.loadLibrary(), or you could modify the PATH to include the directories where your native libraries are stored.
Short answer: for "can't find dependent library" error, check your $PATH (corresponds to bullet point #3 below)
Long answer:
Pure java world: jvm uses "Classpath" to find class files
JNI world (java/native boundary): jvm uses "java.library.path" (which defaults to $PATH) to find dlls
pure native world: native code uses $PATH to load other dlls
I found a great article by some friends at keepsafe that went through the same thing I did. It worked for me, so hopefully it helps you out as well! Have a read if you're interested (The Perils of Loading Native Libraries on Android) or just use
compile 'com.getkeepsafe.relinker:relinker:1.2.3'
and replace
System.loadLibrary("myLibrary");
with
ReLinker.loadLibrary(context, "mylibrary");
installing Microsoft Visual C++ 2010 SP1 Redistributable Fixed it
I used to have exactly the same problem, and finally it was solved.
I put all the dependent DLLs into the same folder where mylib.dll was stored and make sure the JAVA Compiler could find it (if there is no mylib.dll in the compilation path, there would be an error reporting this during compiling). The important thing you need to notice is you must make sure all the dependent libs are of the same version with mylib.dll, for example if your mylib.dll is release version then you should also put the release version of all its dependent libs there.
Hope this could help others who have encountered the same problem.
I had the same issue, and I tried everything what is posted here to fix it but none worked for me.
In my case I'm using Cygwin to compile the dll. It seems that JVM tries to find the JRE DLLs in the virtual Cygwin path.
I added the the Cygwin's virtual directory path to JRE's DLLs and it works now.
I did something like:
SET PATH="/cygdrive/c/Program Files/Java/jdk1.8.0_45";%PATH%
In my situation, I was trying to run a java web service in Tomcat 7 via a connector in Eclipse. The app ran well when I deployed the war file to an instance of Tomcat 7 on my laptop. The app requires a jdbc type 2 driver for "IBM DB2 9.5". For some odd reason the connector in Eclispe could not see or use the paths in the IBM DB2 environment variables, to reach the dll files installed on my laptop as the jcc client. The error message either stated that it failed to find the db2jcct2 dll file or it failed to find the dependent libraries for that dll file. Ultimately, I deleted the connector and rebuilt it. Then it worked properly. I'm adding this solution here as documentation, because I failed to find this specific solution anywhere else.
Creating static library worked for me, compiling using g++ -static. It bundles the dependent libraries along with the build.
place the required dlls in folder and set the folder path in PATH environment variable.
make sure updated environment PATH variable is reflected.
I was facing same issue with ffmpeg library after merging two Android projects as one project.
Actually issue was arriving due to two different versions of ffmpeg library but they were loaded with same names in memory. One library was placed in JNiLibs while other was inside another library used as module. I was not able to modify the code of module as it was readonly so I renamed the one used in my own code to ffmpegCamera and loaded it in memory with same name.
System.loadLibrary("ffmpegCamera");
This resolved the issue and now both versions of libraries are loading well as separate name and process id in memory.
I faced the same problem after migrating my CI into a new machine.
I was still facing it even after applying all the above solutions.
The problem was in my new machine, there was Microsoft Visual C++ 2010 SP1 Redistributable x86 installed in it. But my new machine was having 64-bit CPU and operating system. So the fix was that i just updated and installed the 64 bit version from here .
Go to http://tess4j.sourceforge.net/usage.html and click on Visual C++ Redistributable for VS2012
Download it and run VSU_4\vcredist_x64.exe or VSU_4\vcredist_x84.exe depending upon your system configuration
Put your dll files inside the lib folder, along with your other libraries (eg \lib\win32-x86\your dll files).

How to create native binaries for your Java app? [duplicate]

This question already has answers here:
How can I convert my Java program to an .exe file?
(16 answers)
Closed 3 years ago.
I'm wondering how to package a Java application into a native binary for Windows, Linux and Mac OS X.
I know Minecraft does this, but I can't figure out how. This is what'd I'd like to do:
From NetBeans (preferably) or Eclipse, build the three binaries automatically.
Include native libraries for OpenGL et. all.
Obfuscate my code if possible.
If there's some way to mimic the Minecraft auto-updater feature, that'd be totally awesome.
So, are there any tools available to do this for you, or do I need to write a large bulk of XML to accomplish this?
To make a native binary for Windows, you would use a tool like Launch4J. On OSX you could use JarBundler. Minecraft simply distributes the jar file for Linux. I'm not aware of a native binary packager for Linux.
You could also compile your Java code via GCJ but that's probably not what you want, as there are limitations and compatibility concerns there. The native bundlers like Launch4j and JarBundler simply wrap your jar file and use a real JRE to execute it.
As for integrating with NetBeans or Eclipse, you'll probably have to write your own ant build file, especially since the solution varies from one platform to the next.
If you are using Java 9, you can also use Java 9 Modularization & jlink to ship a zero-dependency native app.
There is also maven-jlink-plugin that could help here.
Take a look at GCJBuilder plugin for eclipse. Not sure if it supports cross compilation as the command GCJ compiler does.
If the app. has a GUI and can be distributed from a web site, look into Java Web Start. JWS is supplied by Oracle, and provides auto-update amongst many other features.
Note that JWS uses Jar files, so no conversion is necessary.
I've used JSMooth for this in the past: http://jsmooth.sourceforge.net/
As mentioned before, this wrapper just looks for a real JRE to run it - it does not come with a bundled JRE.

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