perf(emat): alternate tweaks

[doodlum]

Summary by CodeRabbit

• New Features

  • Added stochastic mip selection for texture sampling in water and material rendering.

• Improvements

  • Refined parallax mapping calculations for water effects and extended materials.
  • Updated version to 1.1.1.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR introduces stochastic mip selection to shader systems by adding a screenNoise parameter to the GetMipLevel function across multiple shader files. It updates the mip level computation with noise-based stochastic adjustments, simplifies parallax numSteps clamping logic, and bumps the ExtendedMaterials version to 1-1-1.

Changes

Cohort / File(s)	Summary
Core Function Signature Update features/Extended Materials/Shaders/ExtendedMaterials/ExtendedMaterials.hlsli	Added screenNoise parameter to public GetMipLevel function; implemented stochastic mip selection using floor/frac logic and noise-based adjustment; simplified parallax numSteps clamping from stepped formula to simple clamp; removed stepSize noise perturbation.
Version Configuration features/Extended Materials/Shaders/Features/ExtendedMaterials.ini	Bumped Version field from 1-1-0 to 1-1-1.
Water Effects Parallax features/Water Effects/Shaders/WaterEffects/WaterParallax.hlsli	Added GetMipLevel overload with screenNoise parameter; integrated screenNoise generation via InterleavedGradientNoise in GetParallaxOffset; updated all three normal texture mip level calculations to pass screenNoise.
Lighting Shader Integration package/Shaders/Lighting.hlsl	Propagated screenNoise parameter to all GetMipLevel calls across EMAT, ENV/Parallax, TRUE_PBR, and terrain variation code paths; updated mip level computation for parallax coordinates.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~15 minutes

Possibly related PRs

• fix: reduce Terrain Variation mip penalty from +2 to +1 for clarity #1236: Modifies GetMipLevel in ExtendedMaterials.hlsli with direct mip computation changes that relate to this PR's signature update.
• perf(terrain variation): custom mip levels & parallax function #1246: Changes mip-selection and parallax sampling functions in ExtendedMaterials, directly complementing the stochastic approach introduced here.
• feat: terrain blending ready for release #1405: Introduces screenNoise-driven stochastic mechanisms in Lighting.hlsl, parallel to this PR's stochastic mip selection implementation.

Suggested reviewers

• alandtse
• davo0411

Poem

🐰 With noise so fine and mips so bright,
Stochastic whispers dance in light,
From terrain deep to water's glow,
Let screenNoise seeds more texture show! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The title 'perf(emat): alternate tweaks' is vague and non-descriptive, using generic terms like 'tweaks' that don't clearly convey the specific changes being made to the codebase.	Consider a more descriptive title such as 'perf(emat): add stochastic mip selection to parallax mapping' or 'perf(emat): optimize parallax mip level computation with screen-space noise' to better communicate the primary change.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
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 docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch emat-tweak

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[github-actions]

Using provided base ref: 5313fbe
Using base ref: 5313fbe
Base commit date: 2026-02-11T12:34:42Z (Wednesday, February 11, 2026 12:34 PM)
No actionable suggestions for changed features.

[github-actions]

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