Saving a VRAM Compressed image is broken in 4.3-dev after RenderingDevice refactor

[aaronfranke]

Tested versions

The issue occurs in the latest master (13a0d6e), it occurs with #83452's merge commit (3a8524d), and all commits I tested between those. The issue does not occur with commits before #83452's merge commit, including 4.2-stable.

System information

macOS 14.2.1, Apple M1 Pro

Issue description

Saving VRAM Compressed images is broken in 4.3-dev as of #83452. I noticed this bug when I tried to export a GLTF scene from Godot and the image data was extremely distorted.

Steps to reproduce

1. Run the minimal reproduction project, which has icon.svg imported as VRAM Compressed, and has this code:

const ICON = preload("res://icon.svg")

func _ready():
	ICON.get_image().save_png("res://output.png")

2. With the latest master, 83452, and commits between, this image is output:

3. With 4.2-stable and commits before 83452, this image is output:

Minimal reproduction project (MRP)

imgsave.zip

[DarioSamo]

I did a quick test since I saw some possibly related code while fixing the render graph in one of the rebase, but it's still corrupted as well on my branch.

It's probably worth mentioning the thumbnail if icon.svg also seems to have the same corruption.

[lyuma]

This issue also breaks all scenes exported as glTF in Godot 4.2

[clayjohn]

@lyuma Can you confirm that the fix in #86855 works?