fix(linear lighting): Fix PBR specular with DALC

[Dlizzio]

Made sure DALC feeding into reflections goes through the same "dimming filter" that other parts of the lighting system use.

Summary by CodeRabbit

• Bug Fixes
  • Improved ambient luminance handling across deferred rendering and dynamic cubemap paths, yielding more consistent and accurate directional ambient/specular lighting in scenes.

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[coderabbitai]

📝 Walkthrough

Walkthrough

A minor shader change: the directional ambient input is now wrapped with Color::Ambient before converting to luminance in two shader files, altering the intermediate luminance used in specular/lighting calculations.

Changes

Cohort / File(s)	Summary
Directional Ambient Luminance Computation package/Shaders/DeferredCompositeCS.hlsl, features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli	Replaced RGBToLuminance(max(0, mul(SharedData::DirectionalAmbient, float4(R, 1.0)))) with RGBToLuminance(Color::Ambient(max(0, mul(SharedData::DirectionalAmbient, float4(R, 1.0))))) in directional ambient/specular luminance calculations (two locations total).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• chore: gamma space normalisation #1535: Modifies directional ambient/specular luminance handling in the same shader code paths.
• perf(ssgi): optimize  #1499: Alters directional ambient/luminance handling in DeferredCompositeCS.hlsl.
• chore: "fix(pbr): metal low-light rendering fixed, improved cubemaps" #1410: Changes specular/ambient computation logic touching DeferredCompositeCS.hlsl.

Suggested reviewers

• jiayev
• doodlum
• alandtse

Poem

🐰 I nibbled code in morning light,
Wrapped ambient snug and made it right,
A tiny hop, a subtle tune,
Luminance gleams beneath the moon 🥕

🚥 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 'fix(linear lighting): Fix PBR specular with DALC' clearly identifies the main change: a fix to PBR specular lighting in relation to DALC (detail ambient lighting contribution), which aligns with the actual code changes that wrap directional ambient calculations with an Ambient() call.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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📜 Recent review details

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Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between adeac45 and 45cec43.

📒 Files selected for processing (1)

• features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli

🧰 Additional context used

📓 Path-based instructions (3)

**/*.{cpp,cxx,cc,c,h,hpp,hxx,hlsl,hlsli,fx,fxh,py}

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Files:

• features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli

features/*/Shaders/**/*.{hlsl,hlsli,fx,fxh}

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Files:

• features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli

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Files:

• features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli

🧠 Learnings (3)

📓 Common learnings

Learnt from: jiayev
Repo: doodlum/skyrim-community-shaders PR: 0
File: :0-0
Timestamp: 2025-08-03T18:37:19.690Z
Learning: ISReflectionsRayTracing.hlsl and ISWorldMap.hlsl in the skyrim-community-shaders repository are image-space post-processing shaders that perform color sampling and blending operations that need proper linear color space handling for the linear lighting system. ISReflectionsRayTracing handles screen-space reflections and should use conditional Color::IrradianceToLinear/Gamma conversions similar to ISCompositeLensFlareVolumetricLighting.hlsl. ISWorldMap performs 7x7 color accumulation that should be done in linear space similar to the pattern used in ISSAOComposite.hlsl.

Learnt from: alandtse
Repo: doodlum/skyrim-community-shaders PR: 0
File: :0-0
Timestamp: 2025-07-05T05:20:45.823Z
Learning: In the skyrim-community-shaders repository, file deletion error handling improvements that replace existence checks and try-catch blocks with std::filesystem::remove error-code-based approaches are considered bug fixes rather than refactoring, as they address inadequate error handling and misleading log messages.

Learnt from: ThePagi
Repo: doodlum/skyrim-community-shaders PR: 1369
File: src/Features/SnowCover.cpp:515-515
Timestamp: 2025-10-02T14:20:33.454Z
Learning: In the Community Shaders codebase (skyrim-community-shaders repository), hardcoded shader resource slot numbers are used directly in code rather than being defined as named constants. This is the established convention and should not be flagged as an issue.

Learnt from: alandtse
Repo: doodlum/skyrim-community-shaders PR: 577
File: features/Wetness Effects/Shaders/WetnessEffects/WetnessEffects.hlsli:57-61
Timestamp: 2025-06-17T05:40:22.785Z
Learning: Default parameter values are supported in the HLSL compiler used by the skyrim-community-shaders project, contrary to standard HLSL (FXC/DXC) limitations.

📚 Learning: 2025-08-03T18:37:19.690Z

Learnt from: jiayev
Repo: doodlum/skyrim-community-shaders PR: 0
File: :0-0
Timestamp: 2025-08-03T18:37:19.690Z
Learning: ISReflectionsRayTracing.hlsl and ISWorldMap.hlsl in the skyrim-community-shaders repository are image-space post-processing shaders that perform color sampling and blending operations that need proper linear color space handling for the linear lighting system. ISReflectionsRayTracing handles screen-space reflections and should use conditional Color::IrradianceToLinear/Gamma conversions similar to ISCompositeLensFlareVolumetricLighting.hlsl. ISWorldMap performs 7x7 color accumulation that should be done in linear space similar to the pattern used in ISSAOComposite.hlsl.

Applied to files:

• features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli

📚 Learning: 2025-07-18T15:21:03.641Z

Learnt from: jiayev
Repo: doodlum/skyrim-community-shaders PR: 0
File: :0-0
Timestamp: 2025-07-18T15:21:03.641Z
Learning: In the skyrim-community-shaders rendering pipeline, materials with alpha < 1 or alpha blending enabled are rendered in non-deferred mode rather than deferred mode. This means issues with dynamic cubemaps on transparent materials are actually non-deferred rendering issues.

Applied to files:

• features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli

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• GitHub Check: Run Shader Unit Tests
• GitHub Check: Validate shader compilation (VR, .github/configs/shader-validation-vr.yaml)
• GitHub Check: Validate shader compilation (Flatrim, .github/configs/shader-validation.yaml)

🔇 Additional comments (1)

features/Dynamic Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli (1)

167-167: LGTM! Consistent DALC handling for reflections.

This change correctly aligns the GetDynamicCubemap function's DALC processing with the pattern already used in GetDynamicCubemapSpecularIrradiance (lines 41-43). Both functions now apply Color::Ambient() to the directional ambient before converting to luminance, ensuring consistent behavior through the lighting pipeline.

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[github-actions]

Using provided base ref: 467ca14
Using base ref: 467ca14
Base commit date: 2026-01-12T21:51:00+09:00 (Monday, January 12, 2026 09:51 PM)
No actionable suggestions for changed features.

[github-actions]

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

[doodlum]

also missing from https://github.com/doodlum/skyrim-community-shaders/blob/467ca14d82f48741350f14d482948ef30a6706ac/features/Dynamic%20Cubemaps/Shaders/DynamicCubemaps/DynamicCubemaps.hlsli#L167