Tweak default SDFGI settings for better quality

[Calinou]

• Enable Read Sky Light to get proper outdoors lighting out of the box.
• Set bounce feedback to 0.5 by default to get a better quality result.
  • Higher values may cause infinite feedback with bright surfaces.
• Increase the number of frames to converge to improve quality at the cost of latency. Most scenes are fairly static after all.
• Use 75% Y scale by default as most scenes are not highly vertical.
• Reorder the Y scale enum to go from the lowest Y scale to the highest. Also rename the "Disabled" setting to "100%" for clarity.

Edit: This PR was amended in May 2021 to not tweak any performance-related settings. Therefore, performance should be roughly identical to what it was before. Performance tweaks were moved to #39965.

[akien-mga]

Needs rebase after #40016.

[clayjohn]

This will still need reduz' final approval, but it looks fine.

[ghost]

i don't think this commit will help at all, there's an issue with the algorithm itself at it's core

[Calinou]

@RaTcHeT302 The new settings definitely help in non-pathological situations. It's just that you apparently ran into a bug with SDFGI.

[aaronfranke]

@Calinou What's the status of this? It seems that this is desired, but this needs a rebase before it can be reviewed and merged.

[Calinou]

@aaronfranke reduz wasn't convinced by all of these default setting changes. I need to discuss this with him again first.

[reduz]

SDFGI needs further work on these areas, will work on it after Alpha

[Calinou]

SDFGI needs further work on these areas, will work on it after Alpha

Shouldn't we enable Read Sky Light by default at least in the meantime? Right now, the SDFGI appearance on outdoor scenes isn't very appealing until you enable that property.

[FilipLundby]

Shouldn't we enable Read Sky Light by default at least in the meantime? Right now, the SDFGI appearance on outdoor scenes isn't very appealing until you enable that property.

It would be nice if it was possible to control the shadow color. When Read sky light is turned on shadows contains a lot of blue (see image 1). Turning Read sky light off makes shadows go black (see image 2).

I am aiming for a more neutral look, like image 3. I would expect the shadow color of the DirectionalLight to be the shadow color, but it doesn't seem to do anything.

The argument might be that the blueish color is more realistic and this might be true, but as a game developer I'm not always going for realism. For winter scene this would be perfect, but for warm summer day it feels out of place.

Just my two cents, other then that, it looks amazing! :)

1. Blue sky and Read sky light on

2. Read sky light off

3. Gray sky and Read sky light on

What the scene and sky looks like

[Calinou]

It would be nice if it was possible to control the shadow color. When Read sky light is turned on shadows contains a lot of blue (see image 1). Turning Read sky light off makes shadows go black (see image 2).

In physically-based rendering, you don't adjust the shadow color. Instead, you adjust the ambient light color. To do this, reduce Sky Contribution in the Environment settings (and optionally set a plain color instead of sourcing the sky for ambient light). When doing this, Read Sky Light should be left enabled.

If the shadow appears colored, it's because the shaded area is only lit by the environment lighting (here, the sky).

I would expect the shadow color of the DirectionalLight to be the shadow color, but it doesn't seem to do anything.

Setting the shadow color is no longer supported for performance reasons. See #49447.

It would be possible to reimplement per-light shadow colors using specialization constants as was done for PCSS-like shadows, but this isn't planned for 4.0. (Specialization constants make it possible to pay the performance cost only if you use the feature in question.)

[FilipLundby]

In physically-based rendering, you don't adjust the shadow color. Instead, you adjust the ambient light color. To do this, reduce Sky Contribution in the Environment settings (and optionally set a plain color instead of sourcing the sky for ambient light). When doing this, Read Sky Light should be left enabled.

Thank you for the feedback @Calinou. I am probably missing something, because your description sounds exactly as how I set up the environment. Ambient color is set to neutral gray and ambient sky contribution is set to 0.

[Calinou]

Thank you for the feedback @Calinou. I am probably missing something, because your description sounds exactly as how I set up the environment. Ambient color is set to neutral gray and ambient sky contribution is set to 0.

After checking locally, this turns out to be a (likely) bug: #55104

[akien-mga]

Approved in PR review meeting.

[akien-mga]

Thanks!