Any info about GL_NV_timer_query?

OpenGL OpenGL: Advanced Coding
1

I was looking into extension set of new beta (leaked) drivers 80.40 and found two new extensions (ARB_pixel_buffer_objects NV_timer_query). First extension is already known, but second one is unknown for me.

I do some investiogation and I didn’t found new entry points. So I suppose it must be able to query something using glGetXXX functions.

Any idea what it sholud do?

yooyo

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By the way, are there any news on NV_conditional_render?

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I would bet that the NV_timer_query extension just defines a new target enum for the glBeginQuery/glEndQuery mechanism.

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Originally posted by Obli:
By the way, are there any news on NV_conditional_render?
Yeah, we already asked that, err… 2 years ago? At least one!

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Originally posted by Eric Lengyel:
I would bet that the NV_timer_query extension just defines a new target enum for the glBeginQuery/glEndQuery mechanism.
I just check for new targets for glBeginQuery (looping from 0 to 0xffff and call glBeginQuery) found new query target: 0x88bf. I’ll continue investigation…

Maybe it can be used for measure rendering performances? Some internal GPU timers?

yooyo

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Seems that glBeginQuery/glEndQuery works!
I do some basic tests:

#define GL_TIMER_QUERY_NV		0x88bf

	GLuint TimeElapsed=0;

	glBeginQueryARB(GL_TIMER_QUERY_NV, m_TimerQuery);
	RenderGrid(1.0f);
	glEndQuery(GL_TIMER_QUERY_NV);
	glGetQueryObjectuivARB(m_TimerQuery, GL_QUERY_RESULT_ARB, &TimeElapsed);

Depending on amount of rendering primitives TimeElapsed has change. If I do not render anything on screen TimeElapsed is close to 1.

Im not sure in which units is this value? GPU clock-tics or nano-sec or micro-sec?

yooyo

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This may be something to do with getting the nvPerfHUD to work in opengl, maybe. Perhaps we’re seeing some of the benefits of nvidia working with sony on the ps3.

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I think it’s more likely the perfkit timers (instead of perfhud). I hope so as using that “performance data helper” windows api is kindof annoying :smiley:
They will then probably only have this in the extension string of the instrumented drivers.

Charles