Vulkan: Volumetric fog without visible FogVolume nodes does not make the editor redraw until it has fully converged

[golddotasksquestions]

Godot version

4.0 Alpha11

System information

Win Nvidea 765M

Issue description

I have also seen this in previous 4.0 versions, but I can't really reproduce reliably:

volumetric_fog_apha11_01.mp4

Steps to reproduce

1. Enable VolumetricFog in the WorldEnvironment
2. Enable Camera Preview
3. Click on nodes in the Scene Panel

Minimal reproduction project

volumetric_fog_cam_preview_bug.zip

[Calinou]

Related to #54892. This needs to be fixed in the same way, by forcing redrawing for a certain amount of frames whenever a volumetric fog parameter is changed or when a viewport is resized. The number of frames that need to be redrawn depends on the temporal reprojection amount chosen. With the default temporal reprojection amount of 0.9, you can reasonably assume that fog will be mostly fully converged after 44 frames drawn (0.9 multiplied by 0.9 44 times <= 0.01).

Alternatively, temporal reprojection could be always disabled in the editor, but this will worsen volumetric fog quality in the editor.

This is effectively the opposite issue as #54893, but it happens only when you have no visible FogVolume nodes in the scene.

[golddotasksquestions]

@Calinou I suppose #62796 is then related to #54892 as well?

[Calinou]

@Calinou I suppose #62796 is then related to #54892 as well?

Yes, #62796 is due to the same cause as this issue, so I'll close it as a duplicate.

You can work this around by enabling Update Continuously in the editor settings, but this will increase CPU/GPU usage. If you enable Show Update Spinner, you can toggle this by clicking the spinner.

[golddotasksquestions]

@Calinou I suppose #62798 probably has the same cause then and can be closed as duplicate as well?

[Calinou]

@Calinou I suppose #62798 then is probably has the same cause as well and can be closed as duplicate?

Indeed, these are all caused by the fog not updating when it should.

[Mantle-Core]

Related to #54892. This needs to be fixed in the same way, by forcing redrawing for a certain amount of frames whenever a volumetric fog parameter is changed or when a viewport is resized. The number of frames that need to be redrawn depends on the temporal reprojection amount chosen. With the default temporal reprojection amount of 0.9, you can reasonably assume that fog will be mostly fully converged after 44 frames drawn (0.9 multiplied by 0.9 44 times <= 0.01).

Alternatively, temporal reprojection could be always disabled in the editor, but this will worsen volumetric fog quality in the editor.

This is effectively the opposite issue as #54893, but it happens only when you have no visible FogVolume nodes in the scene.

@Calinou I took a shot at this issue. Would this be the expected output? At the moment this fix is for viewport resize.

Volume.Fog.mp4

[Calinou]

@Mantle-Core Looks good, but make sure the editor isn't redrawing constantly for no reason after fog is updated. Enable Show Update Spinner in the Editor Settings and look at the top-right corner of the editor. The spinner should stop spinning when fog has fully converged.

To avoid flashes when resizing the viewport, a different solution is needed: #63739
Both can be implemented independently of each other.

[Mantle-Core]

The spinner stops after fully converging. I implemented it to force a redraw for N frames based on the Temporal Reprojection Amount. Afterwards, it stops redrawing.