[Linux] OpenGL Stuttering (with video)

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Lunia
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Joined: Sun Oct 13, 2019 4:06 pm
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[Linux] OpenGL Stuttering (with video)

#1

Post by Lunia » Mon Jul 20, 2020 8:20 am

Hello,

I'm having a weird issue on Linux that doesn't occur in any other OpenGL titles.

Here a video of the issue: https://www.youtube.com/watch?v=IGhT4Pp1YW0

Basically the game runs perfectly fine at 240 Hz at hundreds or thousands of FPS. When I'm standing still and just moving my mouse it's very smooth, as expected.
However when I'm moving the entire geometry, monster sprites and whatnot around me stutter.

The weirdest part about this is that with every game restart the amount of stutter randomizes!
Sometimes I'll have, let's use an arbitrary number: 50% stutter. Restart game, 20% stutter, restart game, 90% stutter, restart game, 60% stutter, restart game, 30% stutter and so on. This seems to inconsistently randomize during gameplay and map changes too.

I've tried FPS capping and Vsync, neither of them help. I've also tried fiddling with the "Allow Flipping" in the NVIDIA X Server Settings, no change. The gl_render_precise setting makes no difference either.

I dug up this old thread: https://forum.zdoom.org/viewtopic.php?f=2&t=46685
It seems to somewhat describe the issue I'm having.
I checked out the src/sdl/i_system.cpp on Zandronum on BitBucket and it still seem to use the old method that this guy claims is broken/bad or whatever.

Ryzen 3800X, GTX 1080 @ 450.57 using 5.7.9-arch1-1.

Is there any fix for this?

EDIT: I just built the latest GZDoom and tested out OpenGL and it has zero issues, probably because it uses SDL2 instead of SDL1.2? Definitely a Zandronum/old ZDoom issue it seems.

Lunia
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Posts: 2
Joined: Sun Oct 13, 2019 4:06 pm
Location: void

Re: [Linux] OpenGL Stuttering (with video)

#2

Post by Lunia » Tue Jul 21, 2020 9:30 am

A little update, I just compiled the latest Zandronum source with the fix from the ZDoom thread applied to the src/sdl/i_system.cpp file and now the game is buttery smooth. Zero stuttering.

Guess I'll submit it to the bug tracker.

DoubleK1LL
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Posts: 3
Joined: Wed Jul 14, 2021 6:01 am

Re: [Linux] OpenGL Stuttering (with video)

#3

Post by DoubleK1LL » Sat Jul 24, 2021 3:14 am

Bug reported by Lunia is here FYI: https://zandronum.com/tracker/view.php?id=3848

And yes, I experience a similar stuttering with Zandronum on Linux and I remember this being an issue even years back. Doesn't occur when utilising Zandronum in Wine.

I actually compiled Zandronum with those changes to i_system.cpp and it didn't completely solve the issue for myself. It was better, but not smooth like the Windows variant.

This definitely needs looking into for the Linux folk, please! :)

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