Vulkan: Strange white artifacts on alpha scissor material due to incorrect mipmap generation for transparent textures

[VP-GAMES]

Godot version

4.0 dev

System information

Linux Ubuntu 20.04.3 LTS

Issue description

Some meshes with alpha scissor material, has strange white edges.

Steps to reproduce

Open attached project to see the presentation.

Minimal reproduction project

Artifacts.zip

[Calinou]

I can confirm this on master 1d21779:

simplescreenrecorder-2022-04-20_12.35.03.mp4

This is due to mipmap generation not being done correctly for transparent textures.

Unlike #57981, changing the texture compression mode from VRAM Compressed to Lossless does not resolve this issue:

Disabling mipmap generation on the texture in the Import dock will resolve this issue. It can make the texture appear grainy at a distance, but given your texture doesn't have much high-frequency detail, it still looks good enough at a distance from my testing:

Can you reproduce this in 3.4.4 (in GLES3)?

[VP-GAMES]

In 3.4.4 (in GLES3) i have to set Flags: Transparent to "TRUE" and change Parameters: Depth Draw Mode to "Opaque Pre-Pass" it's enough, it works good
NoArtifactsGLSE3.zip
.

[lyuma]

Is anyone able to reproduce this with a 4.0 release candidate? I suspect this issue was fixed sometime in the past year

[Calinou]

I can still reproduce this on 4.0.rc3 with the MRP (.godot/ was removed to force a reimport of everything).

However, this is a material configuration issue, not a bug:

Linear Mipmap with Alpha Scissor cutoff 0.05

Notice the visible card edge.

Linear with Alpha Scissor cutoff 0.05

Increasing Alpha Scissor threshold from 0.05 to 0.5 gets rid of the issue with mipmaps enabled:

Linear Mipmap with Alpha Scissor cutoff 0.5

Lastly, this is how the opaque texture looks:

For optimal mipmap generation, I recommend setting the transparent areas' color to be as close as possible to the surrounding opaque areas. This means making the entire background have the leaf's color while keeping transparent pixels, and configuring your image editor to not discard the color values of fully transparent pixels when saving.