Vulkan: WorldEnvironment Glow effect's size is resolution-dependent

[Calinou]

Related to #56911.

Godot version

4.0.dev (fe6c65a)
Still reproducible as of 4.0.dev (ce6de71)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 470.74)

Issue description

The glow effect's size is resolution-dependent. This means the glow effect will appear to be larger as the rendering resolution decreases.

This means the rendering will change in unintended ways depending on the user's monitor resolution. Also, if we implement dynamic resolution scaling and FSR in the future, we need to make sure every effect is as a resolution-independent as possible.

glow-resolution-dependent.mp4

Steps to reproduce

• Enable Glow in WorldEnvironment.
• Create a MeshInstance with a SphereMesh.
• Add a StandardMaterial3D on the SphereMesh, with a bright albedo and/or emission value (to make glow kick in).
• Decrease the 3D resolution scale factor at run-time using get_viewport().scale_3d -= 0.1.

Minimal reproduction project

https://github.com/Calinou/test_fxaa_supersample_master
Press the Up / Down arrow keys to adjust the 3D rendering scale. When doing so, watch the glow effect on the floor become larger as the resolution decreases.

[Calinou]

On Reddit, someone reported a similar issue on master but with the opposite happening. The glow effect became weaker at lower resolutions (possibly because bright details were too small to be represented in the mipmaps)? https://www.reddit.com/r/godot/comments/qucc6i/glow_weakening_at_lower_resolutions_my_mistake_or/

Edit: The issue reported on Reddit was likely similar to #56452, not this one.

[ghost]

I managed to ameliorate the issue a bit by sliding the glow levels around.
The results are okay if the scaling is a power of 2 (0.5, 2, ...) but kind of iffy in-between.
Also, it doesn't work that well if the user uses the outer glow levels.
Also, I used a hardcoded reference resolution of 1920x1080.

demo-.6.mp4

The depth of field effect is stable throughout the scaling range though, so maybe it is possible to reimplement the glow shader in a similar fashion.

Anyway, I pushed the changes to a branch if anybody wants to have a look.

[Calinou]

@ceLoFaN This looks pretty good, especially for depth of field – feel free to open pull requests for this 🙂

Since the changes can be reviewed independently, I would recommend opening two separate pull requests – one for glow, one for depth of field.