fix(skysync): remove sunlight fade and volumetric lighting overrides

[Dlizzio]

Summary by CodeRabbit

• Removed Features

  • Volumetric lighting effects and the separate sky-driven intensity adjustment have been removed.

• New Features

  • Outdoor scenes now apply conditional terrain and cloud shadow multipliers for more nuanced shadow blending.

• Other

  • No other sky behavior changes; overall lighting flow and phase/density calculations remain consistent.

[coderabbitai]

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📝 Walkthrough

Walkthrough

Removed SkySync's volumetric-lighting hook, associated thunk and global intensity factor; deleted related nested types from SkySync header. Adjusted ISVolumetricLightingGenerateCS.hlsl to conditionally apply world shadow factor to shadowContribution when TERRAIN_SHADOWS or CLOUD_SHADOWS are enabled and exterior.

Changes

Cohort / File(s)	Summary
SkySync implementation & API src/Features/SkySync.cpp, src/Features/SkySync.h	Removed runtime thunk hook and its implementation; deleted nested VolumetricLightingDescriptor and ApplyVolumetricLighting_* declarations; removed inline static float volumetricLightingIntensityFactor.
Volumetric lighting shader package/Shaders/ISVolumetricLightingGenerateCS.hlsl	Added conditional multiplication of shadowContribution by world shadow factor when TERRAIN_SHADOWS or CLOUD_SHADOWS are defined and exterior; wraps world-shadow factor application with preprocessor guards.

Sequence Diagram(s)

sequenceDiagram
    participant Shader as "ISVolumetricLightingGenerateCS"
    participant World as "Scene (Interior/Exterior)"
    participant Terrain as "TerrainShadows"
    participant Clouds as "CloudShadows"

    Note over Shader: compute base shadowContribution
    Shader->>World: check interior/exterior
    alt exterior and TERRAIN_SHADOWS
        Shader->>Terrain: GetWorldShadow(positionWS, PosAdjust[eyeIndex], eyeIndex)
        Terrain-->>Shader: terrainShadowMult
        Note right of Shader: shadowContribution *= sqrt(terrainShadowMult)
    end
    alt exterior and CLOUD_SHADOWS
        Shader->>Clouds: GetWorldShadow(positionWS, PosAdjust[eyeIndex], eyeIndex)
        Clouds-->>Shader: cloudShadowMult
        Note right of Shader: shadowContribution *= sqrt(cloudShadowMult)
    end
    Note over Shader: final vl = shadowContribution * densityContribution * phaseContribution

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix(skysync): effect mesh blackout during shadow caster transitions #1965 — touches SkySync volumetric-lighting handling and volumetricLightingIntensityFactor, overlapping removed symbols.
• fix(SkySync): fix CPU side moon luminance calcs #1348 — modifies ShadowFader::SetLighting, related to volumetric-lighting intensity propagation changes.
• fix(terrain shadows): fix brightened lods #1547 — shader change that multiplies volumetric shadowContribution by world shadow sampling, closely related to the shader edits.

Suggested reviewers

• doodlum

Poem

🐰 I hopped through lines at dawn's first gleam,
Untied a hook, let old factors dream,
Clouds and terrain now lend their shade,
I twitch my whiskers — quieter glade,
A tiny patch, a softer beam.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and clearly describes the main changes: removal of sunlight fade and volumetric lighting overrides from the sky-sync implementation, which matches the core modifications across SkySync.cpp, SkySync.h, and the shader file.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[github-actions]

No actionable suggestions for changed features.

[github-actions]

✅ A pre-release build is available for this PR:
Download

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@package/Shaders/ISVolumetricLightingGenerateCS.hlsl`:
- Around line 122-124: The cloud shadow multiplier is being square-rooted here,
which reduces occlusion strength; remove the sqrt and multiply
shadowContribution directly by CloudShadows::GetCloudShadowMult(positionWS.xyz +
PosAdjust[eyeIndex], LinearSampler) when !SharedData::InInterior so volumetric
shafts use the same linear [0,1] attenuation as other shadow sampling code.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: fa637fb6-1419-4967-818c-33c9fbeaafc0

📥 Commits

Reviewing files that changed from the base of the PR and between 82be5fb and 9ba2327.

📒 Files selected for processing (1)

• package/Shaders/ISVolumetricLightingGenerateCS.hlsl

[coderabbitai]

♻️ Duplicate comments (1)

package/Shaders/ISVolumetricLightingGenerateCS.hlsl (1)

123-124: ⚠️ Potential issue | 🟠 Major

Remove the extra sqrt from cloud shadow attenuation.

Line 124 diverges from the shared shadow path in package/Shaders/Common/ShadowSampling.hlsli, which multiplies by CloudShadows::GetCloudShadowMult(...) directly. Keeping the square root here makes volumetric shafts stay brighter than the rest of the scene under the same cloud cover.

Suggested fix

#		if defined(CLOUD_SHADOWS)
-		shadowContribution *= sqrt(CloudShadows::GetCloudShadowMult(worldPos, LinearSampler));
+		shadowContribution *= CloudShadows::GetCloudShadowMult(worldPos, LinearSampler);
#		endif

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@package/Shaders/ISVolumetricLightingGenerateCS.hlsl` around lines 123 - 124,
The volumetric lighting path applies a sqrt to cloud shadow attenuation causing
inconsistent brightness; remove the square-root so shadowContribution is
multiplied directly by CloudShadows::GetCloudShadowMult(worldPos, LinearSampler)
when CLOUD_SHADOWS is defined (i.e., update the code around the
shadowContribution *= sqrt(...) line to match the Common/ShadowSampling.hlsli
behavior and use shadowContribution *= CloudShadows::GetCloudShadowMult(...)).

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Duplicate comments:
In `@package/Shaders/ISVolumetricLightingGenerateCS.hlsl`:
- Around line 123-124: The volumetric lighting path applies a sqrt to cloud
shadow attenuation causing inconsistent brightness; remove the square-root so
shadowContribution is multiplied directly by
CloudShadows::GetCloudShadowMult(worldPos, LinearSampler) when CLOUD_SHADOWS is
defined (i.e., update the code around the shadowContribution *= sqrt(...) line
to match the Common/ShadowSampling.hlsli behavior and use shadowContribution *=
CloudShadows::GetCloudShadowMult(...)).

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 48f7fa69-7402-40b8-8c72-b05a053ff0d1

📥 Commits

Reviewing files that changed from the base of the PR and between 9ba2327 and f30d338.

📒 Files selected for processing (1)

• package/Shaders/ISVolumetricLightingGenerateCS.hlsl

[doodlum]

shouldnt it use getworldshadow

[Dlizzio]

shouldnt it use getworldshadow

VL needs sqrt as you requested

[doodlum]

shouldnt it use getworldshadow

VL needs sqrt as you requested

sqrt on getworldshadow result. thats fine