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Topics - Virtudude

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1
Support / Shadows - Causing JVM crash.
« on: December 02, 2010, 07:40:21 pm »

Hi,

When I enable shadows, using the shadowhelper, around 60 percent of the time I get a JVM fatal error that causes the application to crash. The other 40 percent the shadows are displayed as expected (my avatar casts a shadow on the floor). Below is the error, the stack trace, and snippets of my code. The error is related to the buffer when openGl is drawing the elements. The crash happened outside the Java Virtual Machine in native code.

Code: [Select]
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000000000fc55ea9, pid=2340, tid=8428
#
# JRE version: 6.0_20-b02
# Java VM: Java HotSpot(TM) 64-Bit Server VM (16.3-b01 mixed mode windows-amd64 )
# Problematic frame:
# C  [atio6axx.dll+0x6a5ea9]
#

And the trace:

Code: [Select]
Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j  org.lwjgl.opengl.GL11.nglDrawElements(IIILjava/nio/Buffer;IJ)V+0
j  org.lwjgl.opengl.GL11.glDrawElements(ILjava/nio/IntBuffer;)V+37
j  com.threed.jpct.CompiledInstance.compileToDL()V+139
j  com.threed.jpct.GLBase.compileDLs()V+57
j  com.threed.jpct.AWTGLRenderer.drawVertexArray(Lcom/threed/jpct/AWTDisplayList;I)V+9
j  com.threed.jpct.AWTJPCTCanvas.paintGL()V+149
j  org.lwjgl.opengl.AWTGLCanvas.paint(Ljava/awt/Graphics;)V+165
j  org.lwjgl.opengl.AWTGLCanvas.update(Ljava/awt/Graphics;)V+2

As seen in the above stack, the error occurs when jPCT calls glDrawElements on GL11. I see a few forums that discuss this issue, such as: http://www.gamedev.net/community/forums/topic.asp?topic_id=463211 and http://jmonkeyengine.org/groups/graphics/forum/topic/trouble-with-dynamically-built-geometry/

However, since no one else has posted this error, I’m assuming that I must be doing something wrong. However, the steps are straight forward so I am hoping that this requires a simple change.


Framebuffer mode: FrameBuffer.SAMPLINGMODE_GL_AA_4X
and the width and height is set at runtime based on the browser size calculations.

Also, since this is running in HW mode, I compile the objects as follows:

Code: [Select]
objs.compile(true,  true, true, true, 4000);

My code snippets:

Initialization code for shadow helper (runs only once):

Code: [Select]
projector = new Projector();
projector.setFOV(0.5f);
projector.setYFOV(0.5f);

shadowHelper = new ShadowHelper(jpctWorld, frameBuffer, projector, 2048);
shadowHelper.setCullingMode(false);
shadowHelper.setAmbientLight(new Color(80, 80, 80));
shadowHelper.setLightMode(true);      
shadowHelper.setBorder(1);      
shadowHelper.addCaster(avatar);      
shadowHelper.addReceiver(floor);

Then, in the game loop, after the initialization has completed:

Code: [Select]
frameBuffer.clear();

projector.lookAt(avatar.getTransformedCenter());
projector.setPosition( new SimpleVector(10, -20, 0) );
shadowHelper.updateShadowMap();
shadowHelper.drawScene();

//Code to render scene to buffer, draw to the buffer, etc...
jpctWorld.renderScene( frameBuffer );
jpctWorld.draw( frameBuffer );
frameBuffer.update();
frameBuffer.displayGLOnly();
hardwareOpenGLWorldCanvas.repaint();

Note: when I set the indexed mode to false when compiling objects that cast shadows, that is:
Code: [Select]
objs.compile(true,  true, true, false, 4000);
then I get a similar error, but the  glDrawArrays is called instead of glDrawElements.

Code: [Select]
j  org.lwjgl.opengl.GL11.nglDrawArrays(IIIJ)V+0
j  org.lwjgl.opengl.GL11.glDrawArrays(III)V+20
j  com.threed.jpct.CompiledInstance.compileToDL()V+151

I’ve tried decreasing the shadow buffer to 256 and still the same error. I’ve looked at other code samples and I don’t see any major differences. I don’t see a similar issue on the forum, except one where updating the graphics driver solved the problem. Any suggestions of what I can try would be greatly appreciated (except for update your graphics drivers, because I have done that).  Perhaps the way I am using jPCT to specify the Open GL buffer is incorrect? BTW, my card is an ATI Mobility Radeon HD 4650.

Thanks!

2
Support / Exception handling in AWTJPCTCanvas exceptionOccurred(...) method.
« on: November 26, 2010, 03:31:58 am »
Hi,

I noticed that the jPCT exception handler, specifically in the “exceptionOccurred” handler of AWTJPCTCanvas, is triggering a “java.lang.reflect.ReflectPermission suppressAccessChecks” exception when a LWJGLException exception is thrown since I am running an applet in an environment that does not have the reflection permission set.

The problem is that the jPCT “exceptionOccurred” handler is eating the original LWJGLException, and hence the only exception I see is the secondary ReflectPermission (i.e. the only message I see is: ERROR: Unable to recover: access denied (java.lang.reflect.ReflectPermission suppressAccessChecks). Perhaps this handler is trying to do something with the LWJGL exception, and is using reflection in one way or another.

Is there any way to avoid using reflection in the exceptionOccurred method of AWTJPCTCanvas for those environments where reflection is not permitted?

If this is not possible, can you please print the stack trace of the original LWJGLException so that I know what the root cause is? Note: that the case is when I see the jpct message: "Unable to recover: " -- you may print out the LWJGLException in other cases but without the source I can't say for certain.

By the way, I did find the root cause by doing thread dumps, but this was a hit and miss approach. The issue is that my graphics driver was throwing a opengl.WindowsPeerInfo.nChoosePixelFormat related error since I was using a HW framebuffer mode that is not supported by the default drivers.

Thank you!  ;D
Dave

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