Post by Clark Padmore in Visions of Ethereal jam comments

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I should probably elaborate on my earlier point about VSync.

A lot of software uses VSync, or "Vertical Sync." It tries to prevent "screen tearing," a phenomenon where frames rendering out-of-sync with the monitor's refresh rate results in the halves of two frames rendering at the same time. It does so by limiting the software's ability to process frames to either the refresh rate, or a half divisor of the refresh rate.

For example, in software with VSync, if a monitor has a refresh rate of 60hz, it will always output either 60hz, 30hz, 15hz, etc.. Even if the software could output 72fps or 120fps, it will only process, at most, 60fps. Or, if a monitor has a refresh rate of 75hz, it will always output either 75hz, 37.5hz, etc..

Basically all web browsers, by default, use VSync. Electron, the JavaScript parser that enables GDevelop to output desktop files and previews, is based on Chromium, which is essentially a web browser, so it, too, uses VSync. I'm not sure at present if it is possible to change this, but this results in the strange behavior.

[EDIT: Just saw your 50fps edit, added it to table]

Max FPS	Monitor Refresh Rate	Final FPS
60	60	60
60	75	(75 / 2 ) == 37.5
Unlimited	60	60
Unlimited	75	75
60	50	50

The reason it cuts in half into 37.5fps at a refresh rate of 75hz is because, as the Max FPS is 60, it's going down to the nearest half.

While it might seem quite stupid (and I'm not convinced that it isn't) this is also part of the reality of building HTML5 applications for web browsers, where the standard 60hz monitor is essentially king. Even if you did change the behavior of Electron to make it not use VSync, people's web browsers are going to use VSync, and most people have 60hz monitors.

I hope this doesn't sound patronizing, it's a very complex topic.

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Lukan Peixe1 year ago(+1)

I knew superficially the concept of V-sync, but I didn't know that it only worked with fractions (/2). It makes sense when you think about the concept, which makes me understand the benefit and complexity of Free/G-Sync.

In the medium term, the way this game behaves on the Web won't matter so much, since the final version will have to compile an executable to be able to put it on Steam.

However, if I manage to get a publisher for the consoles, a port of the game would probably be done with a Unity browser running the HTML version of the game.

Anyway, maybe the V-sync is still in the executable. Would working with max frame 0 (unlimited) be a bad practice?

The monitor you used to test the game here at itch, is it 60hz?

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Clark Padmore1 year ago(+1)

"The monitor you used to test the game here at itch, is it 60hz?"

Yes, my monitor is 60hz. As far as I am able to tell, 60hz is the general industry standard for computer monitors. While many high-end gaming hobbyists have a fondness for the fidelity of 75hz, 120hz, and 144hz monitors, the vast majority of software users and game players use monitors or TVs with a refresh rate of 60hz, which has been the NTSC industry standard for decades.

For context: the 60hz standard existed before video games or home computers; it was originally the American standard for AC (alternating current) electric grid frequency. CRT monitors used this as their refresh rate because it was easy to synchronize.

"Anyway, maybe the V-sync is still in the executable. Would working with max frame 0 (unlimited) be a bad practice?"

If the game's coding is going to be mostly or entirely Frame-based, it is probably a bad practice to export with an unlimited max frame rate. If the game's coding is going to be mostly or entirely Time-based, it will matter a lot less.

With Frame-based coding, non-standard refresh rate users are always going to experience problems until they set their monitors to 60hz, but I personally think limiting the frame rate is the correct course of action in this scenario. If the frame rate is unlimited, this can result in insanely high speeds (a game designed for 60fps running at 144fps, for example). If the frame rate is limited, this will result in slowdown, with one exception: 120hz monitors will experience a perfect 60fps. While this is probably a matter of preference, I think a bit of slowdown is preferable to a theoretically large speed-up.

There are no great solutions to this problem. I think a lot of this comes from mismanaged hype on the part of manufacturers of high-end computer monitors. Additionally, this is mostly a result of GDevelop's "Web-First" design philosophy, and while I would personally like it if there was native support for disabling VSync in desktop distributions, I do not currently expect them to devote resources to that, especially while they're still developing the experimental 3D engine.

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Lukan Peixe1 year ago(+1)

I did see somewhere that the 60hz limitation was because of NTSC and powerline frequency (hence why I made that bad multimeter joke earlier). I personally like higher frequencies, but it's not my main concern.

I'll decide exactly what I'm going to do, but I'm going to avoid frame-based programming, to minimize these complications. However, I will continue with tests at 60fps to be closer to the experience most players have.

I'm going to have to come back to the topic of performance at some point, to avoid what happened in your experiment happening, the box method is something I'll be resorting to for sure.

Thanks again for this great conversation, it was a good learning experience! If I manage to finish this project as I want, your name will be in the thanks in the credits and I will give you a game key :)

If at some point you are launching a commercial game, talk to me too, depending on the situation, I can help a little with the promotion.

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Clark Padmore1 year ago(+1)

Thank you for your time. This was an insightful conversation.

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