Screen Artifacting when reading from hint_screen_texture in 3d with Vulkan Mobile Renderer

[JD-The-65th]

Tested versions

Reproducibility is weird.

In 4.0 all the way to 4.2 dev 1 (4.2 dev 2 untested because it crashed immediately on my pc), the issue can't be reproduced.

In 4.2 Dev 3 and later, the issue gets seen, but it's weird. It's like a config setting gets set because in one of the versions I tested, I swear I could see the issue reproduced in 4.1, but I can't reproduce it in 4.1 again.

System information

Godot v4.3.dev3 - SteamOS holo - X11 - Vulkan (Mobile) - integrated AMD Custom GPU 0405 (RADV VANGOGH) () - AMD Custom APU 0405 (8 Threads)

Issue description

When using the Mobile Renderer, a screen artifact can be observed when using a spatial shader that reads from hint_screen_texture. Moving the camera, it can be assumed that the screen artifact is clipping another part of the screen onto the artifacted part.

shader_type spatial;

render_mode unshaded;
uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap_anisotropic;
void vertex() {
	// Called for every vertex the material is visible on.
}

void fragment() {
	// Called for every pixel the material is visible on.

	vec3 color_mix = texture(SCREEN_TEXTURE, SCREEN_UV, 1).rgb;
	ALBEDO = color_mix;

}

bug.mp4

Steps to reproduce

1. Make a new 3d Project using the Vulkan Mobile renderer
2. Make any spatial shader that uses hint_screen_texture
3. Observe

Minimal reproduction project (MRP)

reproduction-project.zip

[clayjohn]

I tested the MRP with 4.2.1 and 4.2-Dev4 and couldn't reproduce in either version.

Have you tested with 4.2.1 or any of the more recent 4.3-Dev builds?

[JD-The-65th]

I've tested it with 4.3 dev 2 and 3, and saw the same behavior. I've downloaded all the major builds of 4.* and only saw it occur in 4.2.* and greater. The video also shows the MRP running on Godot 4.2.

Make sure you're using Vulkan Mobile specifically. It isn't observable on Forward+ or Compatibility.

[clayjohn]

Specs: Godot v4.2.1.stable - Pop!_OS 22.04 LTS - X11 - Vulkan (Mobile) - integrated Intel(R) Xe Graphics (TGL GT2) () - 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz (8 Threads)

Perhaps this issue is unique to your GPU, have you tried updating your drivers?

[JD-The-65th]

Change to the Camera3D node's perspective.

This happens on my Steam Deck, and on my Quest 2, so it doesn't seem to be a driver error.

[clayjohn]

Change to the Camera3D node's perspective.

This happens on my Steam Deck, and on my Quest 2, so it doesn't seem to be a driver error.

[clayjohn]

Could you try the other filter modes, particularly filter_linear_mipmap and filter_linear. I'm wondering if this is an issue with anisotropic filtering on the devices you have tested

[JD-The-65th]

It dissapears when I use filter_linear on my steam deck. My Quest head strap broke, so I'm just gonna use my phone to test on a similar platform.

[JD-The-65th]

Same on my Samsung S21;
Godot v4.2.1.stable - Android - Vulkan (Mobile) - integrated Adreno (TM) 660 - (8 Threads)

[JD-The-65th]

Something interesting is that mipmaps also cause the same exact issue, at least on my steam deck and on my phone.

[clayjohn]

I think that this might be the same issue as #88585 I'll test that issue now too and see if I can reproduce it

Edit: I can't reproduce #88585 on this device either, so I bet its the same issue. I'll test on another device