Aliasing effect on high refresh rate screens

[wjt]

Testing a Windows build on Stephen's laptop just now, there is a strange effect where it looks as if two copies of StoryWeaver are overlaid atop each other. It's most noticeable by the dots in the thimble/helmet being duplicated.

His laptop has 2560×1600 resolution @ 150% scale, 240 Hz refresh rate. My guess is that the refresh rate is the relevant fact.

XP Summary (total 450)

Subdomain	Skill	XP
Engineering: Optimization & Performance	Problem Solving	150
Engineering: Optimization & Performance	Creativity & Design Thinking	150
Engineering: Optimization & Performance	Technical Literacy	150

[wjt]

Here is a video I recorded:

Threadbare.2026-06-17.13-50-44.mp4

Unfortunately you can't see the effect here.

But changing the display refresh rate from 240 Hz to 60 Hz did make the problem go away.

My hypothesis is that Windows is interpolating 3 extra frames per real frame to fill in the gaps.

[wjt]

TIL that my laptop can do 120 Hz refresh. I tried running Threadbare (exported) as a Wayland client with the display set to 120 Hz - can't reproduce.

[felixwalberg]

I am able to reproduce this issue on my Windows 11 machine running with a NVIDIA GeForce GTX 1660 graphics card. My display has a 144 Hz refresh rate, and I notice the pixels seem to blur on the face of StoryWeaver. Transferring the game window to a 60 Hz secondary monitor, the blurring goes away.

[wjt]

I also reproduced this on the Serious Play demo machine. Windows, also with a GeForce GTX card, also with 144 Hz refresh rate. I no longer have access to this machine though!

I skimmed https://docs.godotengine.org/en/stable/tutorials/rendering/jitter_stutter.html and I wonder whether tinkering with the vsync settings and/or setting a fixed FPS would help.

[wjt]

I tagged this as Windows-only but my only proof is that my 120 Hz laptop screen on Linux can't reproduce it.