Jerky movement when vsync turned on (wglSwapIntervalEXT).

andrew111 · 2011-07-18T15:32:31

Hi, I've been searching previous posts here, but I can't find anything to explain my problem. My problem is that with vsync on, my movement is very jerky. I enabled vsync in my program like so: PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress( "wglSwapIntervalEXT" ); if(wglSwapIntervalEXT) { wglSwapIntervalEXT(1); } else { std::cout << "No vsync"; } I am using win32 api for my window. My movement is based on deltaTime. I am using the QueryPerformanceCounter to calculate the deltaTime. Am I missing something here? I haven't been able to find any difference between my vsync code and other peoples'. Thanks.

Graphics and GPU Programming Programming

Started by andrew111 August 13, 2009 06:19 AM

22 comments, last by V-man 12 years, 9 months ago

shurcool

439

July 18, 2011 12:45 AM

I've tried a few more things, and found a software-side fix (band-aid?).

Putting a glFinish() call right before SwapBuffers() makes this stuttering problem go away 99% of the time (there are still a few occasional frame skips).

Putting a glFinish() call right AFTER SwapBuffers() makes it go away 99.99% (or 100%, hard to say) of the time.

It makes no sense to me why you should put glFinish() right after SwapBuffers(), yet it helps this problem go away... So it's definitely a weird ATI driver issue as far as I can tell.

V-man

813

July 18, 2011 01:22 AM

How could it be a ATI driver issue? Are other programs running like that? Also, this thread is 2 years old. I was wondering why my name was the second post. So please, create a new thread. There is no point in bringing up old threads from the grave.

Sig: http://glhlib.sourceforge.net
an open source GLU replacement library. Much more modern than GLU.
float matrix[16], inverse_matrix[16];
glhLoadIdentityf2(matrix);
glhTranslatef2(matrix, 0.0, 0.0, 5.0);
glhRotateAboutXf2(matrix, angleInRadians);
glhScalef2(matrix, 1.0, 1.0, -1.0);
glhQuickInvertMatrixf2(matrix, inverse_matrix);
glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);

shurcool

439

July 18, 2011 03:32 AM

Yes, this is an old thread, but I'm experiencing exactly the same issue as OP. Even with today's drivers (although they're probably not really updating the drivers for Radeon HD 4000 series cards in the latest Catalyst driver packages).

It was the 4th result on Google for ATI and wglSwapIntervalEXT. So I hope it helps others.

[color="#1C2837"]How could it be a ATI driver issue? [color="#1C2837"]Are other programs running like that?[color="#1C2837"]

[color="#1C2837"] [color="#1C2837"]The same .exe runs just fine on other computers with nvidia video cards, and Vsync enabled. It seems DirectX programs aren't affected.

V-man

813

July 18, 2011 03:32 PM

Yes, this is an old thread, but I'm experiencing exactly the same issue as OP. Even with today's drivers (although they're probably not really updating the drivers for Radeon HD 4000 series cards in the latest Catalyst driver packages).

It was the 4th result on Google for ATI and wglSwapIntervalEXT. So I hope it helps others.

[quote name='V-man' timestamp='1310952164' post='4836575'][color="#1c2837"]How could it be a ATI driver issue? [color="#1c2837"]Are other programs running like that?[color="#1c2837"]

[color="#1c2837"]The same .exe runs just fine on other computers with nvidia video cards, and Vsync enabled. It seems DirectX programs aren't affected.
[/quote]

If it is a OpenGL problem, then run other GL games such as the demo version of Quake 3, Doom 3, American Mcgee's Alice, Serious Sam 1

Jerky movement when vsync turned on (wglSwapIntervalEXT).

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Jerky movement when vsync turned on (wglSwapIntervalEXT).

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