Display.update() raising GL error: Invalid value

OpenGL Development
#1

Can someone enlighten me as to what sort of conditions would cause Display.update()'s call to Context.swapBuffers() to raise a GL error: Invalid Value? I see that Display.update() does this:


	// We paint only when the window is visible or dirty
		if (isVisible() || isDirty()) {
			Util.checkGLError();
			try {
				Context.swapBuffers();
			} catch (LWJGLException e) {
				throw new RuntimeException(e);
			}
		}

So the error must be arising from the Context.swapBuffers() call. (I check glError() after Display.update() completes)

The error only occurs the first time I Display.update(), afterwards no error occurs.

Any ideas?

Thanks!

#2

No, thats not the case.

Util.checkGLError(); checks the drivers for any error that might have croped up anywhere in the last frame, Util.checkGLError(); releases those errors to be printed or whatever. You could be doing GL11.glLightf(GL11.glTrue); which is an invalid enum for that method call. Check the rest of your program carefully with a very fine toothcomb, if in doubt, put other Util.checkGLError(); calls in your code to see if the error has cropped up anywhere else…

DP

#3

I wonder that we might tweak the generators so that one can produce a debug version of the GL interface that calls checkGLerror() after every operation. Good idea?

Cas :slight_smile:

#4

well, as long as you can turn it off to avoid the JNI overhead that comes with it, im fine. the server VM should remove the dead-code anyway. IMO, its a good idea a long as performance doesnt suffer.

DP

#5

We could have it so that it literally wrote out a different version of the GL11 class using Ant, and you’d use that whilst in development. I dunno.

Cas :slight_smile:

#6

Very good idea! Will save loads of time.

#7

its not just GL11 - GL20, but all of the extensions too…

If its two seperate jars, im happy and will definetly save alot of time!

DP

#8

Util.checkGLError() checks the gl error state and finds it clean (otherwise it would throw an exception), after Display.update() completes, I check the gl error state and it is not clean (Invalid Value), so something that occured as a result of Context.swapBuffers() set the gl error state. My code is full of gl error checking already. The gl error state is clean when I call Display.update() and dirty when it completes.

#9

Definetly a good idea - oh the wasted hours I could have saved…

#10

Sounds “interesting”. I’d like to help, but I can’t do it without a small self-contained test case. What does the exact exception look like?

  • elias
#11

Ok, if I can narrow it down I will certainly post it. I was hoping maybe someone had seen the behavior before :slight_smile: