Vulkan: Strange black line artifact in SSAO when Half Size is enabled

[josefkaragoli]

Godot version

d26442e

System information

Windows 10, GTX 1060 6GB

Issue description

When SSAO quality is set to above "Low (Fast)" a weird line appears directly in the middle of the screen - it seems like some visual artifact - It always appears, but when ssao_detail is lowered the artifact is less visible, albeit still there.

SSAO OFF

SSAO on Medium

SSAO on Low

I think it doesn't show on low because Low doesn't use the detail pass in SSAO though I'm not sure.

Steps to reproduce

Open any scene in godot. Enable SSAO in the WorldEnvironment, and if you can't see the strange line then increase Detail and Intensity of the SSAO.

Minimal reproduction project

No response

[mrjustaguy]

Half Resolution used?

[josefkaragoli]

Yes, everything at its default settings

[Calinou]

I can confirm this on 4.0.alpha 1b057e1.

A similar issue occurs with SSR and possibly SSIL. This line will move around when you resize the viewport (which happens when resizing the editor window).

[mrjustaguy]

Turn off Half resolution, as if the height/width of half the resolution are not both integers you get issues with it.

I've experienced a similar issue in shipped games (such as Ark Survival Evolved a UE4 title where SSAO had such Lines appearing) where on settings when Screen Space Effects are using half resolution when the Screen Resolution is such that half of it doesn't return Integer values for both.

[Calinou]

Minimal reproduction project: test_ssao_half_size.zip

I can notice flickering when resizing the viewport with Half Size enabled in the Project Settings, but everything looks OK when Half Size is disabled:

SSAO Half Size enabled (default)

simplescreenrecorder-2022-07-10_19.42.18.mp4

SSAO Half Size disabled

simplescreenrecorder-2022-07-10_19.43.04.mp4

I don't notice a line in the middle in either though.

[josefkaragoli]

Turn off Half resolution, as if the height/width of half the resolution are not both integers you get issues with it.

So I suppose the solution would be to ensure the viewport dimensions are always a multiple of 2? I suppose all common screen resolutions are multiples of 2 anyways, eg 2560x1440, 1920x1080, 1366x768... so this is a very corner case bug

[Calinou]

So I suppose the solution would be to ensure the viewport dimensions are always a multiple of 2? I suppose all common screen resolutions are multiples of 2 anyways, eg 2560x1440, 1920x1080, 1366x768... so this is a very corner case bug

See #37995, which was rejected.

[clayjohn]

May be fixed by #72838