UI anims play at the wrong speed when FPS is not set to 60

[Sushiman3000]

Describe the bug

Whenever you set your FPS (Framerate setting) in config.json above or below 60, UI animations will play at the wrong speed.

Setting the Framerate to match your monitor’s refresh rate makes the game run smoothly on high Hz monitors but causes UI animations to play at twice the speed. This issue does not affect characters, explods, stages, or other gameplay elements, only UI animations.

Here’s an example using a character animation as a UI animation (char portrait/face on the select screen):

To Reproduce

1. Set the "Framerate" setting in save/config.json to 120 or 30.
2. Background, power bars, and other animated UI elements will play at the wrong speed.

Expected behavior

Keep UI animations locked at 60 FPS, independent of the "Framerate" setting.

Screenshots / Video

No response

Engine Version (or source code date)

nightly (9/11/24)

Operating system

Windows

Extra context or search terms

No response

[K4thos]

edit: need to investigate it further

[K4thos]

works as expected, that setting affects the rate at which consecutive frames are rendered. Including menu frames. Not sure if we should even externalize it.

[K4thos]

Ok, I see where the problem lies. When you set the Framerate to 120, the entire game runs twice as fast internally, but the in-game speed is halved due to the GameFramerate setting. The game speed is calculated as GameFramerate / Framerate, which in this case equals 0.5. We could potentially use this behavior for screenpack rendering as well.

However, I’m not sure if the Framerate setting should be externalized in the first place. Does running the game with Framerate set to 120 and halving the game speed via GameFramerate set to 60 really make a noticeable difference on a high-refresh-rate monitor compared to Framerate = 60 and GameFramerate = 60?

[Sushiman3000]

It really makes a difference. You can compare it to setting the Framerate to 30 while keeping GameFramerate at 60 on a 60Hz monitor. That's how Framerate at 60 looks on a 120Hz+ monitor, though not as bad, it’s still quite noticeable. I’m referring to in-game performance, while still running at normal speed, there’s a lot of micro-stuttering.

This isn’t an Ikemen only issue though, but a general fps/hz thing issue on all games. 60fps looks smooth on a 60Hz monitor but looks awful on a 120Hz+ monitor. That’s why I think this change would be useful to people with 120Hz or higher monitors, so they can have smooth in-game performance while keeping normal speed UI elements in custom screenpacks with lots of animations.

I can try to provide some examples if that helps.

[potsmugen]

For some things it doesn't make a difference, but with characters for instance Ikemen will deliberately interpolate their movement to make it appear smoother. Lifebars too. The easiest way to see it is setting debug speed to 25%. Chars will still move at 60fps, just slower.

I don't particularly care to set frame rate above 60, but I'm sure many people would get a kick out of running Ikemen like that. Actually I can picture screenpacks with scrolling elements and such also benefitting from it, but that'd require porting the position interpolation to their code.