Threading issues: 2 GLCanvases in one JFrame

OpenGL Development JOGL Development
#1

I have been very pleased with the results of working with JOGL, running under Mac OS 10.3.2, using Java 1.4.2. I have read the User’s Guide and am in a general way aware that there are threading issues with JOGL. I recently encountered such a problem, when I tried to pack two GLCanvases (each representing a different camera viewing the same scene graph) into one JFrame. The program complained as follows:

        java.lang.IllegalMonitorStateException: current thread not owner
              at net.java.games.jogl.impl.JAWT_DrawingSurface.Unlock0(Native Method)
              at net.java.games.jogl.impl.JAWT_DrawingSurface.Unlock(JAWT_DrawingSurface.java:60)
              at net.java.games.jogl.impl.macosx.MacOSXOnscreenGLContext.unlockSurface(MacOSXOnscreenGLContext.java:236)
... (more stack frames)

and also complained about deallocing memory that hadn’t been allocated.

Can someone provide either or both of the following:
1) A simplified explanation of exactly what the thread problem here is?
2) A solution for the problem.

Thanks in advance.

#2

Basically an IllegalMonitorStateException means that a piece of code is calling Object.wait on a object it doesn’t own. Perhaps Greg would comment further since I don’t do Mac. I have an app with 4 GLCanvas working just fine.

#3

Can’t comment specifically on this one yet as I have the same problem. Its not just JOGL canvas instances either. I’ve been having some trouble getting JOGL to work while another OpenGL application was running at the same time.

#4

Note, what you’re doing isn’t the ideal way to do it. What you really want to do is render the multiple camera perspectives into multiple viewports using glViewport - not use multiple canvas instances.