feat(grass lighting): add wrapped lighting toggle

[BigBullmoose]

Adds the option to enable a wrapped lighting model on grass, a function taken from a CS v1.3. Prevents certain grass mods from looking too dark when sunlight is directly overhead.

Summary by CodeRabbit

• New Features

  • Added an "Enable Wrapped Lighting" toggle for grass lighting; renderer now supports both wrapped and standard diffuse lighting modes and the setting is persisted.

• UI

  • Lighting settings include a new checkbox with a hover tooltip explaining wrapped lighting, plus adjusted spacing for clarity.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a toggleable EnableWrappedLighting flag in shader shared data, engine settings/serialization, and UI, and conditions the grass shader to choose between wrapped-lighting math and the original diffuse lighting path.

Changes

Cohort / File(s)	Summary
Shader Shared Data package/Shaders/Common/SharedData.hlsli	Replaced float3 pad0 with bool EnableWrappedLighting and float2 pad0 in GrassLightingSettings, changing struct layout.
Grass Shader Logic package/Shaders/RunGrass.hlsl	Added conditional branch using SharedData::grassLightingSettings.EnableWrappedLighting to select wrapped-lighting math (compute wrapAmount → wrappedDirLight) or the original saturate(dirLightAngle) diffuse accumulation; minor preprocessor formatting changes.
Settings Struct src/Features/GrassLighting.h	Replaced pad[3] with EnableWrappedLighting and pad[2] in GrassLighting::Settings (default false), changing public struct layout and padding.
UI & Serialization src/Features/GrassLighting.cpp	Added EnableWrappedLighting to settings serialization and a checkbox "Enable Wrapped Lighting" in the Grass Lighting UI with tooltip and spacing adjustments.

Sequence Diagram(s)

sequenceDiagram
  participant User
  participant UI
  participant EngineSettings
  participant Shader
  participant GPU

  User->>UI: Toggle "Enable Wrapped Lighting"
  UI->>EngineSettings: Update EnableWrappedLighting
  EngineSettings->>Shader: Supply SharedData (EnableWrappedLighting)
  Shader->>GPU: Execute grass shader per-pixel
  alt EnableWrappedLighting == true
    Shader->>GPU: compute wrapAmount\ncompute wrappedDirLight\naccumulate wrapped diffuse
  else
    Shader->>GPU: compute saturate(dirLightAngle)\naccumulate standard diffuse
  end
  GPU-->>Shader: lighting result
  Shader-->>EngineSettings: render output

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• chore(grass lighting): complex grass improvements #1456 — Modifies wrapped-directional/per-light wrapped lighting math in package/Shaders/RunGrass.hlsl, touching the same shader region.
• perf(ssgi): optimize  #1499 — Also updates lighting paths in package/Shaders/RunGrass.hlsl, related to the conditional lighting changes here.

Suggested reviewers

• jiayev
• doodlum

Poem

🐰
I flipped a switch and watched the blades align,
Wrapped glow or straight — each blade can shine,
A hop, a nibble, a shader's tiny grin,
Green fields shimmer as the day begins. 🌿

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat(grass lighting): add wrapped lighting toggle' directly and clearly summarizes the main change: adding a wrapped lighting toggle feature for grass lighting.

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[github-actions]

Using provided base ref: 7ee4c02
Using base ref: 7ee4c02
Base commit date: 2026-01-15T15:11:03Z (Thursday, January 15, 2026 03:11 PM)
No actionable suggestions for changed features.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@package/Shaders/RunGrass.hlsl`:
- Around line 632-643: The wrapped lighting branch in RunGrass.hlsl (guarded by
SharedData::grassLightingSettings.EnableWrappedLighting) double-applies
dirDetailShadow and omits the grass diffuse multiplier: adjust the
lightsDiffuseColor assignment so it does not multiply by dirDetailShadow again
if dirLightColor already includes it, and add Color::GrassDiffuseMult() just
like the standard branch; specifically, replace the current lightsDiffuseColor
+= dirLightColor * saturate(wrappedDirLight) * dirDetailShadow; with a single
multiplication that uses dirLightColor (no extra dirDetailShadow) times
saturate(wrappedDirLight) times Color::GrassDiffuseMult() to match the standard
model.

[github-actions]

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

[doodlum]

"Old wrapped lighting model from CS 1.3" is not an explanation of what the toggle actually does.

[doodlum]

Point lights do not get the new model

[doodlum]

wrapAmount is duplicated