fix(emat): fix complex mat detection

[jiayev]

Summary by CodeRabbit

• Bug Fixes
  • Enhanced material detection precision in complex lighting and environment-mapping scenarios through improved sampling accuracy and detail refinement.
  • Tightened parallax effect selection criteria to prevent unintended fallback behavior and ensure more predictable visual results across diverse material configurations.

[coderabbitai]

📝 Walkthrough

Walkthrough

The shader's EMAT complex-material env-map path refines two related checks: complexMaterial detection now samples at higher mip-level 15 directly, and the complexMaterialParallax condition is tightened to require the mask value within a bounded range rather than only above a lower threshold.

Changes

EMAT Complex-Material Path

Layer / File(s)	Summary
Complex-material masking and parallax conditions package/Shaders/Lighting.hlsl	complexMaterial detection switched to sample at mip-level 15 directly against (1.0 - kMaskEpsilon), and complexMaterialParallax condition now requires envMaskSample.w in the open interval (kMaskEpsilon, 1.0 - kMaskEpsilon) rather than only above the lower bound.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• community-shaders/skyrim-community-shaders#2032: Both PRs modify Lighting.hlsl's EMAT env-map complex-material and parallax gating by changing epsilon threshold interpretation and sample-level usage.
• community-shaders/skyrim-community-shaders#1327: Both touch the complex-material EMAT path; this PR refines how complex-material masking is derived, while #1327 fixes downstream complex-specular computations using those values.

Suggested reviewers

• doodlum

Poem

A shader tweak, precise and small,
Mip-level whispers through the hall,
Epsilon bounds now left and right,
Parallax gleams with clarity bright,
Hop hop 🐰✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 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.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly describes the fix being applied - it addresses complex material detection (abbreviation: 'cm') in the EMAT environment map path by using a higher-detail mip-level sample and tightening the parallax branch conditions.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch cpm-fix-26526

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[github-actions]

No actionable suggestions for changed features.

[coderabbitai]

🧹 Nitpick comments (1)

package/Shaders/Lighting.hlsl (1)

1113-1123: Improve PR metadata clarity and run shader validation before merge.

Suggested title: fix(emat): refine complex-material mask checks

If this maps to a tracked bug, add Fixes #<id> (or Closes #<id>) in the PR description, and run the repository’s hlslkit validation/compilation step for this shader path before merging.

As per coding guidelines, "**/*.hlsl: Use hlslkit for shader validation and compilation during targeted development testing and before deploymentand**/*`: provide suggestions for Conventional Commit Titles and Issue References."

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@package/Shaders/Lighting.hlsl` around lines 1113 - 1123, Rename the PR to a
clear conventional-commit style title like "fix(emat): refine complex-material
mask checks", add "Fixes #<id>" or "Closes #<id>" in the PR description if this
change resolves a tracked bug, and run the repository's hlslkit
validation/compilation step against package/Shaders/Lighting.hlsl (the code
around complexMaterial, envMaskSample, TexEnvMaskSampler.SampleLevel and
kMaskEpsilon) to ensure the shader compiles cleanly before merging; if
validation reports issues, fix the shader errors reported by hlslkit and re-run
until successful.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@package/Shaders/Lighting.hlsl`:
- Around line 1113-1123: Rename the PR to a clear conventional-commit style
title like "fix(emat): refine complex-material mask checks", add "Fixes #<id>"
or "Closes #<id>" in the PR description if this change resolves a tracked bug,
and run the repository's hlslkit validation/compilation step against
package/Shaders/Lighting.hlsl (the code around complexMaterial, envMaskSample,
TexEnvMaskSampler.SampleLevel and kMaskEpsilon) to ensure the shader compiles
cleanly before merging; if validation reports issues, fix the shader errors
reported by hlslkit and re-run until successful.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 7b7d5b87-bf09-4115-b7cf-bed798f3ff26

📥 Commits

Reviewing files that changed from the base of the PR and between d7e2fa4 and 4ed7a87.

📒 Files selected for processing (1)

• package/Shaders/Lighting.hlsl