Import TextureAtlas as Mesh is not working properly

[nesja]

Godot version:
3.2 stable

OS/device including version:
Windows10 x64 1809

Issue description:
Not sure that issues are the same: #32869 , #35756
Importing TextureAtlas as mesh gives an incorrect results when used in the Sprite and in the AnimatedSprite. The texture is shifted (1) and some frames are distorted and skipped when animation is playing. AnimationFrame panel looks wrong (2)

Output:
drivers/gles3/rasterizer_storage_gles3.cpp:3376 - Condition "!(p_format & VisualServer::ARRAY_FORMAT_VERTEX)" is true.

Debugger:
mesh_add_surface: Condition "!(p_format & VisualServer::ARRAY_FORMAT_VERTEX)" is true.

Steps to reproduce:

• Import TextureAtlas as mesh
• Use imported textures with Sprite node or AnimatedSprite node as AnimationFrames

Minimal reproduction project:
Launch Scene.tscn and switch between the correct AnimatedSprite_texture node (frames imported as textures) and the AnimatedSprite_atlas_mesh node to see the difference:
atlas.zip

[nesja]

I can confirm this behavior on Linux. Generated atlas has artifacts

[jesperkondrup]

We can also confirm this issue (see image).

Also it looks like the orange gizmo box around the sprite just takes the size of the original image instead of "trimming" the alpha from the image. So if you have an image with a large area of transparent pixels (Like I have in my blue circle sprite) you are probably going to end up with a very large orange box, instead of a nice small cropped gizmo box.

[vyshliy]

Same issue in 3.4.2. The selected Sprite (imported as mesh) should be inside this frame. AnimtedSprite is also broken with this sprites like in issue.

[Calinou]

This is likely not a supported use case within AtlasTexture. See godotengine/godot-proposals#1708 and godotengine/godot-proposals#3530.