SSR roughness produces strange horizontal streaks, especially visible when using Normal Maps

[unfa]

Godot version

4.0 beta 2

System information

Windows 10 / Arch Linux; Vulkan, Clustered+, AMD Radeon RX6800XT

Issue description

Screen-Space Reflections respond to roughness by blurring on one axis, which produces strange horizontal streaks, especially when using a normal map. For best case scenario I've set SSR to use highest quality.

Roughness = 0:

Roughness = 0.25:

Roughness = 0 + normal map:

Roughness = 0.25 + normal map:

Roughness = 1.0 + normal map + roughness map:

Let me tweak the floor material to make the reflection more visible:

Roughness = 1 + roughness map:

Roughness = 1 + normal map + roughness map:

These streaks are even more distracting in motion, as they flicker back and forth.

Steps to reproduce

1. Enable SSR
2. Make your material reflective but a bit rough
3. Add a normal map to vary the surface normals
4. Observe the strange horizonal streaks

Minimal reproduction project

SSR Test.zip

[unfa]

Accidentally I've found a really interesting talk about SSR and I think it could be of use in the effort to improve that feature in Godot:

Presentation:
https://www.youtube.com/watch?v=AzXEao-WKRc

Slides:
https://www.ea.com/frostbite/news/stochastic-screen-space-reflections

[unfa]

I wonder - does it make sense to use O3DE's code?
Maybe some of the rendering code could be taken from there and adapted to Godot, or at least used as a close reference.

They boast about their rendering, and it could save Godot devs a lot of time figuring stuff out from scratch, when maybe shader code for screen-space effects could be at least partially reused?

The engine is licensed under Apache 2.0 or MIT: https://github.com/o3de/o3de it's also made in C++ like Godot.

[unfa]

This issue is still present in Beta 12:

[Calinou]

I can confirm this on 4.0.beta12 (Linux, GeForce RTX 4090 with NVIDIA 525.60.11).

Some observations:

• Enabling 16× anisotropic filtering on the texture SSR reflects on doesn't affect streaks.
• Streaks are more noticeable with heavy SSR settings (lots of steps, fade in/fade out that makes reflections more visible). At the default settings, they're not that noticeable as reflections are shorter.
• Adjusting Max Steps, Fade In, Fade Out, Depth Tolerance has no effect on the streaks.
• Disabling Screen Space Roughness Limiter in the advanced Project Settings has no effect on the streaks.

[akien-mga]

Still reproducible in 4.0 RC 1.