Jittering and Non Screen Tearing even when disabling V-Sync

[owstetra]

Godot version

Godot 4 Alpha 2

System information

Windows 10 - GTX 980

Issue description

After disabling V-Sync the screen tearing is gone, it should appear, also the game Start jittering and stuttering, and when enabling V-Sync the game still jittering/stuttering
In Alpha 1 after disabling V-Sync, the screen tearing will appear, but there is no Jitter, and the game runs very smooth no matter what compared to Alpha 2
All of this happen when in Full screen

Edit : You can download this Advanced movement system template and test it, Before you test it add this line of code in _ready()

DisplayServer.window_set_mode(DisplayServer.WINDOW_MODE_FULLSCREEN)

now open it in Alpha 1, You will see the game runs very smooth, but in Alpha 2 the game stuttering, press shift to run and rotate the camera around you and you will see

Steps to reproduce

in any 3D project that contain a fast moving camera, open it in Alpha 1 and Alpha 2, and see the difference

Minimal reproduction project

None
_

[akien-mga]

Might be related to Windows fullscreen mode changes @bruvzg.

[owstetra]

Might be related to Windows fullscreen mode changes @bruvzg.

i retested it again in window mode, the issue still there too
it feels laggy and jittery when moving the camera in game

[bruvzg]

Might be related to #57928 (no it's not in alpha 2), fullscreen mode should have at least the same performance as window mode.

[Calinou]

Jitter and stutter will always happen to an extent when you have V-Sync disabled, because the physics step does not match the rendered frame rate. Physics interpolation fixes this by ensuring every rendered frame "sees" a different physics state, but it's not implemented yet.

If you need physics interpolation right now, you could try porting https://github.com/lawnjelly/smoothing-addon to master.

[owstetra]

Jitter and stutter will always happen to an extent when you have V-Sync disabled, because the physics step does not match the rendered frame rate. Physics interpolation fixes this by ensuring every rendered frame "sees" a different physics state, but it's not implemented yet.

If you need physics interpolation right now, you could try porting https://github.com/lawnjelly/smoothing-addon to master.

The problem is not with physics interpolation, no... it will never Jitter/Stutter at all if V-Sync is disabled in any game or engine, you maybe mean Screen tearing ?
Because in Alpha 1 there is no Jitter/Stutter at all when moving the camera in 3D when the V-Sync is disabled and there is Screen Tearing
But in Alpha 2 There is Jitter/Stutter but there is no Screen tearing when V-Sync is disabled, and even if V-Sync is Enabled the Stutter is still there

[Calinou]

@owstetra If you can compile the engine from source, you could look into bisecting the regression to greatly speed up troubleshooting.

[bruvzg]

snap_controls_to_pixels was broken and restored in #57481, and it probably reintroduced #28804 issue (this was fixed and reverted multiple times in 3.x). But this should not affect 3D, so probably is not the only reason.

[owstetra]

Here's something, You can download this Advanced movement system template and test it, Before you test it add this line of code in _ready()
DisplayServer.window_set_mode(DisplayServer.WINDOW_MODE_FULLSCREEN)

now open it in Alpha 1, You will see the game runs very smooth, but in Alpha 2 the game stuttering, You can press shift to run and rotate the camera around you, it's hard to see at first but you will feel it and start seeing it

[akien-mga]

Is this still reproducible in 4.0 RC 3 or later?

[dreamsComeTrue]

yes, I can confirm that - I still get jiter movement when VSync is enabled. When I disable it, it's also there but less noticeable.
I have the simplest scene: CharacterBody3D with _physics_process adjusting it's Velocity and then move_and_collide()
I am using latest 4.1 version of Godot

[akien-mga]

Might be the same issue as #84137 - presumably a Windows DWM bug.