fix: fix bright character lighting

[doodlum]

Summary by CodeRabbit

• New Features
  • Character lighting now uses subtle noise-based modulation, adding per-pixel variation to shading.
  • Improves visual depth and realism on characters, reducing flat, uniform lighting and banding artifacts.
  • Enhances consistency of lighting across different viewing conditions without changing gameplay.

[coderabbitai]

Walkthrough

Introduces per-pixel modulation of character light intensity by multiplying CharacterLightParams.z with a sampled noise texture value using baseShadowUV in package/Shaders/Lighting.hlsl. The clamped range using CharacterLightParams.w and zero remains unchanged.

Changes

Cohort / File(s)	Summary of changes
Lighting shader noise modulation package/Shaders/Lighting.hlsl	Modified charLightColor to multiply CharacterLightParams.z by TexCharacterLightProjNoiseSampler.Sample(..., baseShadowUV).x, adding per-pixel noise-based modulation; clamping logic preserved.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• alandtse

Poem

I nibble at photons, hop through the night,
Sprinkling soft noise on the character light.
A dapple, a shimmer, a speckled delight—
Per-pixel confetti in shadered sight.
Boop! goes the bunny, rendering just right. 🐇✨

✨ Finishing Touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch character-lighting-fix

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[github-actions]

Using provided base ref: 3bed38c
Using base ref: 3bed38c
Base commit date: 2025-09-08T17:00:21+01:00 (Monday, September 08, 2025 05:00 PM)
No actionable suggestions for changed features.

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

package/Shaders/Lighting.hlsl (1)

2709-2713: Use dynamic-res-adjusted UV for noise; avoid screen-space mismatch and VR drift

Sampling the noise with baseShadowUV ignores VPOSOffset and dynamic-resolution adjustments applied to shadowUV. In VR or when dynamic resolution changes, this can cause pattern drift/flicker. Sample the noise with the same adjusted UV path for consistency. Also clamp the sampled value to [0,1] to be safe.

@@
   if (Permutation::PixelShaderDescriptor & Permutation::LightingFlags::CharacterLight) {
     float charLightMul = saturate(dot(viewDirection, worldNormal.xyz)) * CharacterLightParams.x + CharacterLightParams.y * saturate(dot(float2(0.164398998, -0.986393988), worldNormal.yz));
-    float charLightColor = min(CharacterLightParams.w, max(0, CharacterLightParams.z * TexCharacterLightProjNoiseSampler.Sample(SampCharacterLightProjNoiseSampler, baseShadowUV).x));
+    // Use the same dynamic-res + VPOS adjusted path as shadow sampling to keep the pattern stable.
+    float2 charNoiseUV = FrameBuffer::GetDynamicResolutionAdjustedScreenPosition(baseShadowUV * VPOSOffset.xy + VPOSOffset.zw);
+    float charNoise = saturate(TexCharacterLightProjNoiseSampler.Sample(SampCharacterLightProjNoiseSampler, charNoiseUV).x);
+    float charLightColor = min(CharacterLightParams.w, max(0, CharacterLightParams.z * charNoise));
     diffuseColor += (charLightMul * charLightColor).xxx;
   }

Verification:

• Test with dynamic resolution on/off and in VR; look for stability of the character-light pattern during camera pans.
• Optional: if you want a crisper dither, consider SampleLevel(..., 0) for charNoise to avoid mip smoothing.

📜 Review details

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Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3bed38c and 30ba056.

📒 Files selected for processing (1)

• package/Shaders/Lighting.hlsl (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

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

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

Do not include TODO/FIXME placeholders; provide complete, working solutions

Files:

• package/Shaders/Lighting.hlsl

🧠 Learnings (2)

📓 Common learnings

Learnt from: alandtse
PR: doodlum/skyrim-community-shaders#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.

📚 Learning: 2025-08-03T18:37:19.690Z

Learnt from: jiayev
PR: doodlum/skyrim-community-shaders#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:

• package/Shaders/Lighting.hlsl

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• GitHub Check: Validate shader compilation (Flatrim, .github/configs/shader-validation.yaml)
• GitHub Check: Validate shader compilation (VR, .github/configs/shader-validation-vr.yaml)
• GitHub Check: Build plugin and addons

[github-actions]

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