AutoExposure flickering wildly when framebuffer allocation = 2D

[slavfox]

Godot version: 81292665d5dcc991d3c9341245b269193329ee22 (latest master as of this issue), but occurs since at least 3.1

OS/device including version: Antergos, kernel 5.0.4-arch1-1-ARCH NVIDIA GeForce GTX 1080 Ti, proprietary drivers, version 418.56

Issue description: AutoExposure causes screen to flicker like it has a personal vendetta against people with epilepsy when there is a sprite with a normalmap on-screen and the framebuffer allocation is set to 2D. Possibly related to #16224?

Steps to reproduce:

• Set Project Settings -> Rendering -> Quality -> Intended Usage -> Framebuffer Allocation to 2D
• Create a Sprite with a normal map texture in a 2D scene
• Add a WorldEnvironment node with Background Mode = Canvas and Auto Exposure enabled

Minimal reproduction project: bugrepro.tar.gz

[slavfox]

Workaround is to set framebuffer allocation to 3D.

[KoBeWi]

Still valid in 3.2.4 beta3 No flicker in ef2d1f6, but no background either 🤔

[h0lley]

I was about to submit an issue which is very likely to be the same as this one already reported here, but then luckily searched one more time. In my case, I identified that it occurs in combination with the gui/theme/custom_font project setting.

Auto exposure in 2D breaks in combination with gui/theme/custom_font

Godot version:

3.3.rc8.official

OS/device including version:

Ubuntu (Kubuntu 20.04), Nvidia GPU (nothing else tested)

Issue description:

The game flickers with default settings for auto exposure in 2D. It should no flicker with these settings.

Steps to reproduce: Please download the minimal reproduction project.

1. Open in Godot, run via F5 and confirm the flickering.
2. Checkout environment.tres and confirm that the auto exposure settings are fine / shouldn't cause this kind of flickering.

The issue is peculiar to me as I'd never have imagined for the gui/theme/custom_font project setting to affect auto exposure post-processing, but here's what I learned as I tried to reduce the reproduction project as much as possible:

• Project settings: Framebuffer allocation needs to be 2D
• Project settings: A custom default font needs to be specified
• A Label node needs to be used (doesn't matter if text is empty or not)
• A TextureRect node needs to be used (texture must be set, but in the case of ImageTexture, it doesn't matter if image remains null or not)
• There needs to be a scene change via get_tree.change_scene() between the scene that has the Label in it and the one that has the TextureRect in it. At least for the flickering variant of this issue to occur. You can put the Label and the TextureRect on the same scene as well - then you don't get flickering - but unexpected behavior in relation to auto exposure still. I doubt the use of Label and TextureRect specifically is a prerequisite for the issue to occur though.

Minimal reproduction project:

2d_auto_exposure_bug.zip

[h0lley]

as a follow up on this, the strange reproduction requirements I listed in my earlier comment are not directly connected to this issue, but rather, the flickering can apparently be caused by memory allocation in general.

in my current (non-minimal) project, the flickering does not occur - however, when I change a load into a preload in one specific file, which of course should have no bearing on world environment effects whatsoever, then it flickers.

issue last confirmed in 3.5.beta1.