fix: fix effect blending

[doodlum]

Summary by CodeRabbit

• New Features
  • Improved deferred rendering for multi-blend materials/decals, enabling an additional output channel to enhance visual fidelity in complex surfaces.
• Bug Fixes
  • Resolved a rendering issue that could occur in non–multi-blend configurations by preventing unintended writes to an unavailable output, reducing potential artifacts and stability problems.

[coderabbitai]

Walkthrough

The shader PS_OUTPUT struct in package/Shaders/Effect.hlsl was modified to conditionally include an Albedo render target in deferred mode when MULTBLEND or MULTBLEND_DECAL are defined. Corresponding write logic was removed from non-MULTBLEND paths to avoid referencing an undeclared field.

Changes

Cohort / File(s)	Summary
Deferred G-Buffer outputs package/Shaders/Effect.hlsl	Added conditional member float4 Albedo : SV_Target3; within #ifdef DEFERRED when MULTBLEND or MULTBLEND_DECAL are defined. Removed Albedo writes from non-MULTBLEND code path in PS main to match conditional declaration.

Sequence Diagram(s)

sequenceDiagram
    participant Engine
    participant Compiler as HLSL Compiler
    participant PS as Pixel Shader (PS_OUTPUT)

    Engine->>Compiler: Compile Effect.hlsl with defines
    alt DEFERRED && (MULTBLEND || MULTBLEND_DECAL)
        note over PS: PS_OUTPUT includes Albedo (SV_Target3)
        Engine->>PS: Execute fragment
        rect rgba(200,230,255,0.3)
        PS->>Engine: Outputs NormalGlossiness, Albedo, Specular, ...
        end
    else
        note over PS: PS_OUTPUT excludes Albedo
        Engine->>PS: Execute fragment
        rect rgba(255,230,200,0.3)
        PS->>Engine: Outputs NormalGlossiness, Specular, ... (no Albedo)
        end
    end

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• alandtse

Poem

A whisk of light on render night,
I blend my hues with gentle might—
When flags are set, Albedo gleams,
Else, I hop past deferred streams.
Carrots compiled, targets aligned,
A shader bunny, color-defined. 🥕✨

Pre-merge checks and finishing touches

✅ 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: fix effect blending" correctly indicates the intent to repair blending-related shader behavior and matches the changes that add a conditional Albedo SV_Target3 and prevent writing it when not declared; therefore it is directly related to the changeset. The phrasing is redundant ("fix: fix") and not as specific as it could be about the DEFERRED/MULTBLEND context, but it still conveys the primary purpose. Overall the title is acceptable for reviewers scanning history.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch burley-fix-2

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[github-actions]

Using provided base ref: 3f462fa
Using base ref: 3f462fa
Base commit date: 2025-09-18T00:36:38+01:00 (Thursday, September 18, 2025 12:36 AM)
No actionable suggestions for changed features.

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

package/Shaders/Effect.hlsl (1)

858-863: Confirm intent: MULTBLEND path mirrors Diffuse into Specular/Reflectance/Masks.

If downstream only needs Albedo for effect blending, consider keeping Specular/Reflectance/Masks neutral (zeros) to reduce bandwidth and avoid contaminating G‑buffer channels. If mirroring is required, a short comment here would prevent future regressions.

📜 Review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3f462fa and b767f8f.

📒 Files selected for processing (1)

• package/Shaders/Effect.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/Effect.hlsl

🧠 Learnings (1)

📓 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.

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

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (3)

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

🔇 Additional comments (1)

package/Shaders/Effect.hlsl (1)

430-432: Verify RTV slot 3 is bound for MULTBLEND permutations

Automated sweep failed (ripgrep: "unrecognized file type: hlsl"); cannot confirm bindings. Confirm that when MULTBLEND or MULTBLEND_DECAL + DEFERRED are compiled the render pass binds an RTV at SV_Target3 and that Albedo's color space (linear vs sRGB) matches the compositor.

File: package/Shaders/Effect.hlsl lines 430-432

Run these locally to verify:

# 1) find Albedo declarations using SV_Target3
rg -nP -C2 --glob '**/*.hlsl' '\bAlbedo\s*:\s*SV_Target3\b' || true

# 2) locate engine code that binds multiple RTVs (inspect results for >=4 RTVs)
rg -nP -C3 --glob '**/*.{cpp,c,h}' '(OMSetRenderTargets\(|OMSetRenderTargetsAndUnorderedAccessViews\(|SetRenderTargets\(|CreateRenderTargetView\(|BindRenderTargets)' || true

# 3) search for engine-side Albedo attachment names or color-space hints
rg -nP -C2 --glob '**/*.{cpp,hlsl,h}' '\bAlbedo\b.*(RTV|RenderTarget|Attachment|SV_Target3|sRGB|SRGB|gamma|linear)' || true

[github-actions]

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