feat(ISL): added light size control

[sicsix]

• Adds new setting to control the size of an ISL light source
• Can be set in .esp plugin files using reused FOV parameter or through Light Placer JSON
• Light Placer PR adding support is Add support for light size for Inverse Square Lighting powerof3/LightPlacer#20

Summary by CodeRabbit

• New Features

  • Added a new "Size" parameter for inverse square lights, allowing users to adjust light falloff based on field of view.
  • Updated the light editor UI with new sliders for "Size" and "Cutoff" for inverse square lights.

• Improvements

  • Enhanced attenuation and radius calculations to incorporate the new "Size" parameter, resulting in more accurate and customizable lighting effects.
  • Improved handling and assignment of light properties such as fade and radius for better consistency.

• Bug Fixes

  • Addressed synchronization issues in light data assignment for both inverse square and standard lights.

[coderabbitai]

Walkthrough

This change introduces and propagates a new "size" parameter for lights, derived from the field of view (FOV), into both C++ and shader code. It updates attenuation and radius calculations, modifies struct layouts to include the size field, and adjusts the light editor UI to support editing this new parameter for inverse square lights.

Changes

Cohort / File(s)	Change Summary
Shader Attenuation Update features/Inverse Square Lighting/Shaders/InverseSquareLighting/InverseSquareLighting.hlsli	Modified attenuation calculation in GetAttenuation to include light size squared, altering the attenuation falloff behavior based on the new size parameter.
Shader Light Struct Layout features/Light Limit Fix/Shaders/LightLimitFix/Common.hlsli	Reordered and added float members (fade, invRadius, fadeZone, size) after color and radius; moved invRadius and fadeZone from end; added two uint paddings (pad0, pad1) at the end of the Light struct.
Core Attenuation & Radius Logic src/Features/InverseSquareLighting.cpp, src/Features/InverseSquareLighting.h	Incorporated the size parameter throughout the inverse square lighting calculations, updated function signatures, and ensured size is stored and propagated in runtime data and processing functions.
Runtime Light Data Struct src/Features/InverseSquareLighting/Common.h	Changed radius from a vector to a float, added pad1C and size float members to RuntimeLightDataExt struct.
Light Editor UI/Logic src/Features/InverseSquareLighting/LightEditor.cpp	Updated UI and logic to support editing the new size parameter for inverse square lights, adjusted radius assignment, and improved cutoff override handling.
Light Limit Fix Shader & Struct src/Features/LightLimitFix.cpp, src/Features/LightLimitFix.h	Added fade assignment in the light setup logic; updated LightData struct to add fade, invRadius, fadeZone, and size fields, with padding at the end.
Configuration Update features/Inverse Square Lighting/Shaders/Features/InverseSquareLighting.ini	Updated version number from 1-0-0 to 1-1-0.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant LightEditor
    participant RuntimeLightData
    participant Shader

    User->>LightEditor: Adjusts light FOV/size in UI
    LightEditor->>RuntimeLightData: Updates size and radius fields
    RuntimeLightData->>Shader: Passes size and radius to shader
    Shader->>Shader: Calculates attenuation using size in denominator

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~18 minutes

Possibly related PRs

• fix(ISL): stealth light level calculations #1254: Related to inverse square lighting changes; this PR modifies attenuation calculation by incorporating light size, while fix(ISL): stealth light level calculations #1254 adds a luminance override thunk for inverse square lights.

Suggested reviewers

• alandtse

Poem

A rabbit hopped with coding delight,
As lights grew smarter, shining bright.
With size and fade, the beams now play,
Attenuation falls the modern way.
From code to shader, changes flow—
Illuminating scenes with a radiant glow!
🐇💡✨

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📥 Commits

Reviewing files that changed from the base of the PR and between 3a8ef8c and 2b8cb60.

📒 Files selected for processing (1)

• package/Shaders/Common/PBR.hlsli (1 hunks)

🧰 Additional context used

🧠 Learnings (1)

📓 Common learnings

Learnt from: alandtse
PR: doodlum/skyrim-community-shaders#0
File: :0-0
Timestamp: 2025-06-24T07:17:36.604Z
Learning: When reviewing PRs, always clarify the scope if there are multiple related features or dependencies. WeatherPicker was a separate PR that was already merged, while this PR focuses specifically on WetnessEffects climate preset system enhancements.

Learnt from: alandtse
PR: doodlum/skyrim-community-shaders#577
File: features/Wetness Effects/Shaders/WetnessEffects/WetnessEffects.hlsli:57-61
Timestamp: 2025-06-17T05:40:22.785Z
Learning: Default parameter values are supported in the HLSL compiler used by the skyrim-community-shaders project, contrary to standard HLSL (FXC/DXC) limitations.

Learnt from: alandtse
PR: doodlum/skyrim-community-shaders#577
File: src/Features/WetnessEffects.h:36-36
Timestamp: 2025-06-08T11:25:14.536Z
Learning: In the skyrim-community-shaders project, boolean flags in C++ structs that interface with HLSL shaders use `uint` type instead of `bool` for compatibility reasons. This ensures consistent 4-byte size, proper 16-byte alignment in constant buffers, and cross-platform compatibility when passing data between C++ and HLSL shaders.

Learnt from: davo0411
PR: doodlum/skyrim-community-shaders#1070
File: src/State.cpp:79-83
Timestamp: 2025-05-30T11:44:15.542Z
Learning: In the Skyrim Community Shaders project, the `smoothDrawCalls` array in the `State` class is declared as type `double` in `src/State.h`, which is the correct floating-point type for performing exponential moving average smoothing calculations.

🔇 Additional comments (1)

package/Shaders/Common/PBR.hlsli (1)

150-150: Mathematical correctness fix for power function.

The addition of abs() ensures the base of the power function is non-negative, preventing undefined behavior when NdotV + ao becomes negative. This is mathematically necessary since pow(x, y) with negative x and non-integer y is undefined in real numbers. The exponent exp2(-16.0 * roughness - 1.0) is typically non-integer, making this protection essential for stable shader execution.

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[github-actions]

Using provided base ref: 58ab563
Using base ref: 58ab563
Base commit date: 2025-07-30T20:11:53-07:00 (Wednesday, July 30, 2025 08:11 PM)
No actionable suggestions for changed features.

[github-actions]

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