Problem when using an external context

Hello,

We have a C app which creates its own OpenGL context, and pass it to JOGL:
- we create a Java VM
- before starting the drawing in C, when we are sure that we have a valid OpenGL context available, we call a Java method through JNI where we get a GLDrawableFactory, and then call the createExternalContext method
- then we can draw our OpenGL content in JOGL

This worked ok in JOGL 1.1.1, but not in JOGL 2.0 rc5. However, there is no crash at all, only it seems that the Hava code never goes after the part where it tries to get the factory.

Is it a bug in the current rc5 version of JOGL, or us it that we forgot to do something before trying to get the factory (which was not necessary in 1.1.1) ?.

FYI, the same version work ok when standalone.

Any clues?

Hervé

Hi

It was working fine with JOGL 2 in April 2011. I didn't try this mechanism later.

What do you mean by "FYI, the same version work ok when standalone"?

Please could you try the latest auto build instead of the RC5?

Hi

It was working fine with JOGL 2 in April 2011. I didn't try this mechanism later.

What do you mean by "FYI, the same version work ok when standalone"?

Please could you try the latest auto build instead of the RC5?

Julien Gouesse
http://tuer.sourceforge.net
http://gouessej.wordpress.com

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NAML

About the fact that it seems to work ok when standalone: when I'm using JOGL for the same app but not using an external context (that is, creating a GLJPanel and using it directly), I have no problem. Which is why I think that my "install" of the JOGL libraries is fine. Of course I still can be wrong.

Please enable all debug logs and maybe use the composable debug pipeline (see DebugGL*). Look at our wiki if you don't see what I mean.

Hello, we still have the problem with the latest autobuild, but we were able to track where the problem takes place.

What we do is:

GLProfile profile = GLProfile.getDefault();
GLDrawableFactory factory = GLDrawableFactory.getFactory(profile);
GLContext context = factory.createExternalGLContext();

It works fine if we call this portion of code "standalone," (directly from the Java code while having no external context), except for the last line of course, but it is to be expected.

Now if we begin a drawing in C, then execute the method where we have this code in Java through JNI, we have no problem until the last line. The debugger shows that the problem arise in the wglGetCurrentContext method (WGL class) :

final long __addr_ = wglProcAddressTable._addressof_wglGetCurrentContext;
    if (__addr_ == 0) {
      throw new GLException("Method \"wglGetCurrentContext\" not available");
    }
return dispatch_wglGetCurrentContext1(__addr_);

__addr__ is not null, but dispatch_wglGetCurrentContext1, which is a native method, return null (We are on Windows XP 32 bits).

Herve

The explanation is here:
http://msdn.microsoft.com/en-us/library/dd374383%28v=vs.85%29.aspx

If the calling thread has a current OpenGL rendering context, wglGetCurrentContext returns a handle to that rendering context. Otherwise, the return value is NULL.

Maybe the context is not current when you try to create an external context. Be aware that the context becomes available later in JOGL 2 than in JOGL 1 but it concerns the Java side.

arghh you may be right. When you say "later", does it mean that we have to wait a little in the Java side for the context to be available ? It's true that we called the createExternalGLContext method in Java as soon as possible in the Java side (not because it was really necessary for us though, just because we did not think about it as it worked with JOGL 1.1.1).

However thanks for your advice, but also for your work on this very good API.

On 03/29/2012 01:13 AM, herve [via jogamp] wrote: Thank you :)

We currently use GLDrawableFactory.createExternalGLContext()
in GLJPanel for it's Java2D-OpenGL-Backend and in the SWT unit test
'TestSWTEclipseGLCanvas01GLn'.

We currently use GLDrawableFactory.createExternalGLDrawable()
only in GLJPanel right now ..

Both work use cases work pretty well, having ensured that at the time
they are called (fetching the current context and drawable from JOGL),
the 'external' entity has set them current.

If you like, I would appreciate more unit tests on this.
You could simply create the 'external' context w/ JOGL itself
and hook it up with with the above mentioned calls and using them.

Then we would merge your unit test code and it will be maintained well.

The problem w/ your current negative experience is that we have no way
to validate your description and reproduce it, since we have no source code.

Kind regards, Sven

Hello, thanks again! Our project is Open Sourced (http://sourceforge.net/projects/j661/), but you would need a much smaller test case as our current use case because as you can expect there is a lot of "noise" unrelated to JOGL in our project ;)

However I'm really OK for providing a test case, at the very least it could help others which might have the same difficulties as we have now (and soon "had", I'm sure).

Regards,

Herve

On 03/29/2012 03:06 AM, herve [via jogamp] wrote: Sounds great. Looking forward testing your unit test.

Cheers, Sven

> Regards,
>
> Herve

I see that one more "big" French corporation uses JOGL.

I use createExternalGLContext with GLCanvas in Ardor3D, it works fine. The context of the GLCanvas is not available when creating it, only when adding it into a container whereas in JOGL 1, it was available at its creation. Do you see what I mean?

Hello!

Now it works!! As you wrote: "The context of the GLCanvas is not available when creating it, only when adding it into a container whereas in JOGL 1, it was available at its creation". It was exactly our problem. We tried to access the context only once * before * putting something in our GLJPanel. when we add the widget structure before trying to access the context, it works ok.

Again thanks, your advices were precious!

And yes, Dassault uses JOGL too. I suspect that the J661 project may not be the only one to use it, but at least this one is Open Source ;)

Herve

P.S.: What we are doing in fact is create a Swing structure inside the GLJPanel, and directly call paint on the top of our structure on a Graphics2D which in fact write in a JOGL Texture. After we end drawing the Swing tree, we render the texture on the OpenGL context in JOGL too. Of course we don't recreate the texture at every draw order.

We can't easily use direct OpenGL drawings for that because ARINC 661 widgets are really like Java widgets, and we really need Look and Feel capabilities.

Hi

I'm really happy for you. I had forgotten this tiny change and I had got only a NullPointerException until I remembered to take care of this.

Maybe you could have a look at JOGL based Java2D implementation, I put the link into the user guide. In my humble opinion, it would allow you to stay away from GLJPanel and to draw all Java-like widgets faster.

That's here:
http://forum.jogamp.org/useful-Java2D-bridge-td3391708.html

That's here:
http://forum.jogamp.org/useful-Java2D-bridge-td3391708.html

Julien Gouesse
http://tuer.sourceforge.net
http://gouessej.wordpress.com

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NAML

I know Agile2D a bit too. The idea behind the bridge is almost the same but it is actively maintained. It would be fine to succeed in using it with JFreeChart, we could display nice charts with JOGL. The only limitation of this bridge is that there are still some dependencies with AWT.

I know Agile2D a bit too. The idea behind the bridge is almost the same but it is actively maintained. It would be fine to succeed in using it with JFreeChart, we could display nice charts with JOGL. The only limitation of this bridge is that there are still some dependencies with AWT.

Julien Gouesse
http://tuer.sourceforge.net
http://gouessej.wordpress.com

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NAML

Any help is welcome :)