Arch Linux

laochailan

Member

Registered: 2010-01-08

Posts: 17

ubiquitous lag with OpenGL

ok, I have been trying a while and now I am out of ideas. Basically I have the following problem: I seem not to be able to render anything under any circumstances fluently using OpenGL. This applies to a simple example of a moving dot as well as to some game I have been working on. But look at it yourself if you don't mind compiling this little test program http://paste.pocoo.org/show/352985/ (allegro5 required). The problem is hard to see at first, especially if you have a low quality monitor, but it is overly annoying.

We really tested this in variety of different environments, different distributions (Arch Linux, OpenSUSE), different video drivers (r300/r300g/nvidia), sometimes bleeding edge sometimes stable.

The example waits for vsync but also with disabled vsync it won't do any better, the "gaps" become shorter with higher framerates though.

I hope anyone has an idea what could cause this. my newest suspect is my opengl environment because i only experienced it in 2d applications so far.

akephalos

Member

From: Romania

Registered: 2009-04-22

Posts: 114

Re: ubiquitous lag with OpenGL

So what's the problem, what should one see? I ran your program, I see it running normally... or what?

I modified it a bit to actually see something, replacing...

glBegin(GL_POINTS);
glVertex3f(10,(3*i)%480,0);

with...

glBegin(GL_TRIANGLES);
glVertex3f(10,(i/10)%480,0);
glVertex3f(20,(i/10)%480,0);
glVertex3f(15,(i/10)%480-10,0);

laochailan

Member

Registered: 2010-01-08

Posts: 17

Re: ubiquitous lag with OpenGL

You should see small "spikes" in the animation. i chose GL_POINTS because they actually jump several pixels in those spikes. at the moment i'm just ignoring the problem and programming further, hoping it will not be too annoying in the final program.