build(hlsl): address warnings

[alandtse]

Summary by CodeRabbit

• Bug Fixes

  • Improved PQ color encoding and HDR tone-mapping stability to prevent visual artifacts in edge cases.

• Improvements

  • Enhanced texture sampling quality in lighting and specular calculations through better gradient-based filtering.
  • Optimized shader calculations for improved performance and numerical stability.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR modifies eight shader files to improve numerical safety and parameter propagation. Changes include adding clamping and absolute-value operations before exponentiation, propagating UV derivatives through the lighting pipeline, replacing division with bit-shift operations, and initializing a shader output struct.

Changes

Cohort / File(s)	Summary
Exponentiation Safety package/Shaders/Common/Color.hlsli, package/Shaders/ISHDR.hlsl	Added clamping and absolute-value operations before pow() calls to prevent negative-value exponentiation: pow(max(0.0, color), M1) and pow(abs(A), 1.0/3.0) patterns replace direct pow() calls.
UV Derivative Propagation package/Shaders/Common/LightingEval.hlsli, package/Shaders/Lighting.hlsl	Extended lighting functions to accept and propagate UV derivatives (uv_ddx, uv_ddy): EvaluateLighting and VanillaSpecular signatures updated to pass derivatives through the lighting pipeline using gradient-based texture sampling.
Arithmetic Operation Changes package/Shaders/Common/VR.hlsli, package/Shaders/Menu/BackgroundBlurHorizontal.hlsl, package/Shaders/Menu/BackgroundBlurVertical.hlsl	Replaced integer division with bitwise right-shift for half-value computation: samples / 2 → samples >> 1 and frameDim.x / 2 → (uint)frameDim.x >> 1.
Initialization package/Shaders/Water.hlsl	Changed shader output struct declaration from uninitialized to explicitly zeroed: VS_OUTPUT vsout = (VS_OUTPUT)0;.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• chore: improve contrast function #1470: Modifies HDR contrast remapping in ISHDR.hlsl with pow-based computations.
• feat: improved hdr post processing #1445: Modifies ISHDR.hlsl tonemapping with exponentiation and clamped bases.
• build: fix warnings #1505: Modifies exponentiation and contrast handling in ISHDR.hlsl with pow-base changes.

Suggested reviewers

• doodlum
• jiayev

Poem

🐰 With pow and clamps, we find the way,
Safe from negatives that led astray!
Derivatives flow through the lighting's dance,
Right-shifts replace division's stance—
Shaders bloom with proper care! ✨

🚥 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 accurately reflects the main objective of the PR, which is to address shader compilation warnings across multiple HLSL files by adding input clamping and modifying arithmetic operations.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

No actionable suggestions for changed features.

[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/ISHDR.hlsl`:
- Around line 177-179: The contrast normalization divides by avgValue.x which
can be zero; update the computation of contrastedColorModified (and its use when
blending into contrastedColor) to guard avgValue.x with a small positive epsilon
or conditional fallback so you never divide by zero — e.g., compute a safeAvg =
max(avgValue.x, epsilon) and use safeAvg in the pow(abs(tintedColor) / safeAvg,
Cinematic.z) * safeAvg * sign(tintedColor) expression, and ensure the
lerp/saturate blend still behaves correctly when avgValue.x was originally zero.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 8aa84570-11d5-4213-8b6e-11468c65ef1d

📥 Commits

Reviewing files that changed from the base of the PR and between 8a67f36 and 2d22a94.

📒 Files selected for processing (8)

• package/Shaders/Common/Color.hlsli
• package/Shaders/Common/LightingEval.hlsli
• package/Shaders/Common/VR.hlsli
• package/Shaders/ISHDR.hlsl
• package/Shaders/Lighting.hlsl
• package/Shaders/Menu/BackgroundBlurHorizontal.hlsl
• package/Shaders/Menu/BackgroundBlurVertical.hlsl
• package/Shaders/Water.hlsl

[github-actions]

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