build(hlsl): fix warnings

[alandtse]

Summary by CodeRabbit

• Bug Fixes
  • Improved stability of color and lighting calculations by ensuring negative values are handled safely in various shaders.
  • Fixed initialization of local variables in multiple shaders to prevent undefined behavior.
  • Corrected vector operations and type consistency in water and lighting shaders.
  • Enhanced reliability of terrain, hair, and skylighting computations with clearer and safer mathematical operations.

[coderabbitai]

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Walkthrough

This change set applies explicit absolute value operations to inputs of power functions across multiple HLSL shader files. It ensures that negative values are converted to non-negative before exponentiation, addressing potential issues with invalid or undefined results. Additionally, several shader variables are now explicitly zero-initialized, and a minor vector calculation bug is fixed.

Changes

Cohort / File(s)	Change Summary
Terrain Height Weight Abs Handling features/Extended Materials/Shaders/ExtendedMaterials/ExtendedMaterials.hlsli	Applies abs() to terrain height weights before exponentiation in ProcessTerrainHeightWeights, ensuring non-negative bases for the power function.
Hair Shading Abs Handling features/Hair Specular/Shaders/Hair/Hair.hlsli, package/Shaders/Common/PBR.hlsli	Applies abs() before exponentiation in hair shading calculations, affecting the computation of scatterFresnel2 and hair transmission terms.
IBL and Color Channel Extraction features/IBL/Shaders/IBL/DiffuseIBLCS.hlsl	Explicitly extracts .xyz (RGB) from sampled float4 color, ensuring only RGB channels are used in spherical harmonics coefficient accumulation.
Cluster Building Abs Handling features/Light Limit Fix/Shaders/LightLimitFix/ClusterBuildingCS.hlsl	Applies abs() to the light range ratio before exponentiation in cluster near/far calculations.
Cluster Culling Loop Variable Rename features/Light Limit Fix/Shaders/LightLimitFix/ClusterCullingCS.hlsl	Renames a loop variable from i to j in the copy loop for visible light indices; logic remains unchanged.
Skylighting Probe Validity Refactor features/Skylighting/Shaders/Skylighting/UpdateProbesCS.hlsl	Refactors probe validity check with intermediate variables and explicit type casts for clarity and correctness.
Terrain Shadow Height Initialization features/Terrain Shadows/Shaders/TerrainShadows/ShadowUpdate.cs.hlsl	Changes pastHeights initialization to explicit zero, ensuring defined value before conditional assignment.
Color Space Conversion Abs Handling package/Shaders/Common/Color.hlsli, package/Shaders/Common/DisplayMapping.hlsli, package/Shaders/Common/FrameBuffer.hlsli	Applies abs() to color values before exponentiation in gamma/linear conversions and PQ mapping, ensuring non-negative power function inputs.
Shader Output Zero Initialization package/Shaders/DistantTree.hlsl, package/Shaders/Effect.hlsl, package/Shaders/RunGrass.hlsl	Initializes shader output structs to zero at declaration using casts, ensuring all fields are set to zero initially.
Water Shader Initialization and Vector Fix package/Shaders/Water.hlsl	Changes initialization of float variables to 0.0, and corrects a vector subtraction bug in the pixel shader main function.

Sequence Diagram(s)

sequenceDiagram
    participant ShaderFunction
    participant InputValue
    participant AbsFunction
    participant PowFunction
    participant Output

    ShaderFunction->>InputValue: Receives input (may be negative)
    ShaderFunction->>AbsFunction: Applies abs(input)
    AbsFunction->>PowFunction: Passes non-negative value
    PowFunction->>Output: Raises to power and returns result

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• perf(Terrain Variation): feature rework, miplevel & sample optimisation #1224: Refactors and modifies ProcessTerrainHeightWeights in the same file and namespace, directly related to the terrain height weight handling in this PR.
• refactor(hair): enhance hair specular visual, change default hair settings and feature info #1203: Applies abs() before exponentiation in hair shading code, similar to the pattern used in this PR but for different shader modules.

Poem

A whisker twitch, a shader fix,
Abs before pow—no negative tricks!
Colors and heights, all safe and bright,
Zeroed-out structs, outputs just right.
With every hop, the code grows clear,
This bunny reviews with a gleeful cheer! 🐇✨

Note

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Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between d14a976 and c5b568e.

📒 Files selected for processing (1)

• features/Skylighting/Shaders/Skylighting/UpdateProbesCS.hlsl (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• features/Skylighting/Shaders/Skylighting/UpdateProbesCS.hlsl

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[Copilot]

Pull Request Overview

This PR fixes various HLSL compiler warnings by addressing initialization issues and negative base value warnings in power functions across multiple shader files.

• Proper initialization of output structures and variables to prevent uninitialized variable warnings
• Wrapping power function bases with abs() to avoid warnings about negative values raised to fractional powers
• Fixing syntax errors in function calls and variable declarations

Reviewed Changes

Copilot reviewed 15 out of 17 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
package/Shaders/Water.hlsl	Standardizes float initialization format and fixes function call syntax
package/Shaders/RunGrass.hlsl	Initializes PS_OUTPUT structure to zero
package/Shaders/Effect.hlsl	Initializes PS_OUTPUT structure to zero
package/Shaders/DistantTree.hlsl	Initializes VS_OUTPUT structure to zero
package/Shaders/Common/PBR.hlsli	Wraps BaseColor with abs() in pow() calls
package/Shaders/Common/FrameBuffer.hlsli	Wraps linearColor with abs() in pow() call
package/Shaders/Common/DisplayMapping.hlsli	Wraps pow() function bases with abs()
package/Shaders/Common/Color.hlsli	Wraps color values with abs() in pow() calls
features/Terrain Shadows/Shaders/TerrainShadows/ShadowUpdate.cs.hlsl	Initializes float2 variable to zero
features/Skylighting/Shaders/Skylighting/UpdateProbesCS.hlsl	Fixes type conversion issues with signed/unsigned comparisons
features/Light Limit Fix/Shaders/LightLimitFix/ClusterCullingCS.hlsl	Renames loop variable to avoid conflicts
features/Light Limit Fix/Shaders/LightLimitFix/ClusterBuildingCS.hlsl	Wraps division result with abs() in pow() calls
features/IBL/Shaders/IBL/DiffuseIBLCS.hlsl	Adds explicit .xyz swizzle to texture sample
features/Hair Specular/Shaders/Hair/Hair.hlsli	Wraps subtraction result with abs() in pow() call
features/Extended Materials/Shaders/ExtendedMaterials/ExtendedMaterials.hlsli	Wraps weights with abs() in pow() call

[github-actions]

Using provided base ref: 24f8d4f
Using base ref: 24f8d4f
Base commit date: 2025-08-04T21:50:56-07:00 (Monday, August 04, 2025 09:50 PM)
No actionable suggestions for changed features.

[github-actions]

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