fullscreen makes movement jittery

DJM

whenever i set my scene to fullscreen instead of 1920*1080 my player movement becomes jittery what is the reason for this? godot version 4 alpha6

DJM

enabling vsync fixed it why is that?

Megalomaniak

Unless you are using a adaptive sync monitor, I'd say that vsync is likely desirable anyways. A little bit of input lag as a cost in return of getting rid of all the tearing and jitter is not a bad deal, but the choice should probably be exposed for the players in settings.

To answer your question, it's likely up to frame time consistency. V-Sync likely helps achieve a more consistent frame timing and thus a smoother experience.

It's hard to say for sure tho, with vsync off are you just rendering so many more frames(but still in a consistent timing) that you see a lot of consistent tearing or is the frame timing actually an unpredictable mess on your hw config when vsync is off? That is something you'll have to debug yourself.

DJM

@Megalomaniak said: Unless you are using a adaptive sync monitor, I'd say that vsync is likely desirable anyways. A little bit of input lag as a cost in return of getting rid of all the tearing and jitter is not a bad deal, but the choice should probably be exposed for the players in settings.

To answer your question, it's likely up to frame time consistency. V-Sync likely helps achieve a more consistent frame timing and thus a smoother experience.

It's hard to say for sure tho, with vsync off are you just rendering so many more frames(but still in a consistent timing) that you see a lot of consistent tearing or is the frame timing actually an unpredictable mess on your hw config when vsync is off? That is something you'll have to debug yourself.

when vsync is on i get constant 60fps > no jitter with vsync off constant around 200fps> some jitter but not constant it probably has to do with some physics calculating i guess.

Megalomaniak

I would look at frame time/ms plot/graph rather than FPS numbers.

https://docs.godotengine.org/en/latest/tutorials/scripting/debug/the_profiler.html

DJM

player movement and camera do appear smooth its the objects that do calculations based on player and camera position/rotation that become jittery could this be an alpha issue? im on linux code used to run fine in godot3

Megalomaniak

I wouldn't rule out 'alpha issues' but at the same time, not everything is going to be an 'alpha issue'/bug. How are these jittery objects being moved? In process() or is the logic in physics_process()?

DJM

im not sure if it runs in physics process i am calling a func in physics process like this>

func _physics_process(delta):
	
	process_movement_inputs()
	process_vertical_movement(delta)
	process_movement(delta)

func process_movement(delta):
	
	# Apply Effects
	process_movement_effects( delta)
	#apply bob is where the objects are moved
	ApplyBob(delta)
	
	playfootsounds()

Calinou

If you don't use physics interpolation, there will always be jitter when the rendered FPS doesn't match the physics FPS (60 by default). You can make this less noticeable by increasing Physics FPS to a multiple of the original value in the Project Settings (such as 120, 180, 240, …). This can also reduce tunnelling and improve simulation accuracy, at the cost of increased CPU usage. However, the jittering issue will not completely go away until you use physics interpolation.

https://github.com/lawnjelly/smoothing-addon hasn't been ported to Godot 4 yet, but there are plans to add physics interpolation to core before Godot 4.0 is released anyway.

DJM

@Calinou said: If you don't use physics interpolation, there will always be jitter when the rendered FPS doesn't match the physics FPS (60 by default). You can make this less noticeable by increasing Physics FPS to a multiple of the original value in the Project Settings (such as 120, 180, 240, …). This can also reduce tunnelling and improve simulation accuracy, at the cost of increased CPU usage. However, the jittering issue will not completely go away until you use physics interpolation.

https://github.com/lawnjelly/smoothing-addon hasn't been ported to Godot 4 yet, but there are plans to add physics interpolation to core before Godot 4.0 is released anyway.

adding physics interpolation to core in godot 4 would be great.

cybereality

You pretty much always want to use VSync. It's much smoother if you have a FreeSync monitor, but even then you do want VSync on as well. The people that claim VSync off is better are wannabe pro gamers that don't know what they are talking about. While VSync does add some slight amount of latency, you would have to be a professional CS:GO player to notice. There have been numerous tests of this and we would be talking about 1 frame of latency at most (33ms on a 60Hz monitor) but in many cases it could be much less like in the 10ms range. It's not noticeable and honestly most of these people saying you should disable VSync don't understand how it works. Especially if you have a high refresh 144Hz monitor with FreeSync, it is 100x better with VSync. And if you can't afford a decent monitor, you shouldn't be pretending to be a pro gamer (while gaming at 60Hz). You can buy high refresh monitors for like $150, they are not even expensive. But I just stopped arguing with those people, cause they have no clue how game engines or monitor technology work.

Calinou

The people that claim VSync off is better are wannabe pro gamers that don't know what they are talking about.

There are a lot of legitimate use cases for disabling V-Sync, including drawing applications where minimizing input lag is crucial. Even Android now allows disabling V-Sync in select cases (it's intended to be disabled for drawing applications).

While VSync does add some slight amount of latency, you would have to be a professional CS:GO player to notice.

Most people can notice input lag changes as low as 1-5 milliseconds. This does not require your reaction time to be remotely this low – but you'll easily notice the difference with things such as mouse movement.

VRR (FreeSync/G-Sync) input lag is better than not using VRR, but it's worse than not using any kind of V-Sync. On the bright side, you don't have tearing when using VRR, but it can also suffer from various software issues (especially on Linux where support is spotty).

cybereality

I understand, but the drawbacks of VSync off are much worse, horrible tearing and uneven, choppy frame rate. While enabling VSync does have some latency, it is relatively consistent and smooth. Which is why a lot of console games (at least on PS4 era) locked at 30 fps, because it was a better experience, rather than variable between 30 - 60 because of the frametime inconsistency.

Megalomaniak

@cybereality said: You pretty much always want to use VSync. It's much smoother if you have a FreeSync monitor, but even then you do want VSync on as well. The people that claim VSync off is better are wannabe pro gamers that don't know what they are talking about.

I typically leave vsync off and have radeon chill on in drivers, since many game engines don't properly support my monitors refresh rate of 75Hz, they either cap to 60 or jump up to 90 instead.

edit: I should clarify that it is a freesync monitor, a cheapo HDMI freesync monitor with a range of 40 to 75 from before 144 herz ones became cheap.

cybereality

Yeah, Radeon Chill also works. I used it before on Windows but it's not an option on Linux AFAIK.

DJM

i think vsync should be an option to choose from the player settings. physics interpolation added to core in godot4 is the best solution i guess

cybereality

In Godot 4.0 I think you can enable and disable it with code, probably in VisualServer, but I didn't look into it.