PBR skies are too bright when using Low Graphics quality

[Dan-Linden]

Test plan

1. Run the ExtraFPS viewer
2. Find Nacon's Planet Matricon in Inventory / Library / Environments / PBR / Nacon / Nacon's Unusual Skies
3. Right click "Nacon's Planet Matricon" and Apply Only To Myself
4. Open Preferences > Graphics and move the Graphics & Speed slider to Low, then Low+, then Mid
5. Verify the brightness of terrain, objects and avatars on Low looks similar to Low+ and Mid.

Environment

Environment

Second Life Release 7.1.11.12363455226 (64bit)
Release Notes

You are at 233.7, 124.1, 22.8 in Bug Island 2 located at simhost-0f3c0adbe7168dba4.agni
SLURL: http://maps.secondlife.com/secondlife/Bug%20Island%202/234/124/23
(global coordinates 260,586.0, 249,468.0, 22.8)
Second Life Server 2024-12-17.12379604629
Release Notes

CPU: AMD Ryzen 9 5980HX with Radeon Graphics (3293.73 MHz)
Memory: 15775 MB
OS Version: Microsoft Windows 11 64-bit (Build 22631.4751)
Graphics Card Vendor: ATI Technologies Inc.
Graphics Card: AMD Radeon RX 6800M

Windows Graphics Driver Version: 30.0.15020.1001
OpenGL Version: 4.6.14800 Core Profile Context 21.50.20.01 30.0.15020.1001

Window size: 1680x979
Font Size Adjustment: 96pt
UI Scaling: 1
Draw distance: 64m
Bandwidth: 3000kbit/s
LOD factor: 1.125
Render quality: 0
Texture memory: 4095MB
Disk cache: Max size 1638.4 MB (0.1% used)

J2C Decoder Version: KDU v7.10.4
Audio Driver Version: OpenAL, version 1.1 ALSOFT 1.23.1 / OpenAL Community / OpenAL Soft: OpenAL Soft
Dullahan: 1.14.0.202408091639
CEF: 118.4.1+g3dd6078+chromium-118.0.5993.54
Chromium: 118.0.5993.54
LibVLC Version: 3.0.21
Voice Server Version: Vivox 4.10.0000.32327.5fc3fe7c.5942f08

Packets Lost: 0/7,607 (0.0%)
February 05 2025 14:38:52

Description

This is related to #3503
PBR skies that rely on reflection probes look too bright when using the Low Graphics quality.

Reproduction steps

Repro:

1. Run the ExtraFPS viewer
2. Find Nacon's Planet Matricon in Inventory / Library / Environments / PBR / Nacon / Nacon's Unusual Skies
3. Right click "Nacon's Planet Matricon" and Apply Only To Myself
4. Open Preferences > Graphics
5. Move the Graphics & Speed slider to Low

Observed: The terrain and objects appear very bright or white

Expected: The Low mode should not be unusably bright when viewing newer skies that rely on reflection probes. At the least, consider adding a note to the UI that Low mode is a compatibility mode and will not look good in all circumstances.
Here is what this sky should look like:

Note: Enabling "HDR and Emissive" while in Low Graphics does not fix this brightness issue because Reflection probes are still disabled.

[kylelinden]

Need to fix, this would make a 6.6.17 users experience on forced "Low" mode in 7.x viewers much too bright.