WGSL shaders support PCF shadows

[mvaligursky]

• improved support for texture types during WGSL processing (depth textures mostly)
• converted shadow related GLSL -> WGSL and got it to work

[Copilot]

Pull Request Overview

This PR introduces WGSL support for PCF shadows while also converting several GLSL shadow functions and associated declarations to WGSL syntax. Key changes include updating shadow sampling implementations (PCF1, PCF3, and PCF5), converting light function code to WGSL using pointer parameters where needed, and updating shader processor regex and uniform declarations for WGSL.

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/scene/shader-lib/chunks/lit/frag/lighting/shadowPCF5.js	Minor cleanup in JS shadow function (removal of extraneous empty line).
src/scene/shader-lib/chunks-wgsl/lit/frag/pass-shadow/litShadowMain.js	New WGSL entry point for shadow rendering with updated depth handling.
src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/lightFunctionShadow.js	Converted shadow-sample functions from GLSL to WGSL with pointer usage for light direction update.
src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/lightDeclaration.js	Updated uniform declarations to WGSL (arrays and texture/sampler types).
src/platform/graphics/webgpu/webgpu-shader-processor-wgsl.js	Revised regex and texture type handling to support new WGSL syntax.
Others	Similar WGSL conversion updates for PCF3, PCF1, cascaded shadows, and clustered light shadow functions.

Comments suppressed due to low confidence (4)

src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/lightFunctionShadow.js:12

• [nitpick] Consider adding an inline comment or documentation to clarify the intent and semantics of passing 'lightDir' as a pointer for modification, to ensure consistent comprehension among future maintainers.

fn getShadowSampleCoord{i}(shadowTransform: mat4x4f, shadowParams: vec4f, worldPosition: vec3f, lightPos: vec3f, lightDir: ptr<function, vec3f>, lightDirNorm: vec3f, normal: vec3f) -> vec3f {

src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/lightDeclaration.js:65

• [nitpick] Confirm that all consuming code correctly handles the array access syntax for 'light{i}_shadowMatrixPalette', as the WGSL array type differs from the previous GLSL-style declaration.

uniform light{i}_shadowMatrixPalette: array<mat4x4f, 4>;

src/platform/graphics/webgpu/webgpu-shader-processor-wgsl.js:200

• Verify that this new regex adequately captures all intended texture declarations—in particular, types with more complex or multiple template parameters—to avoid potential mismatches during shader processing.

const TEXTURE_REGEX = /^\s*var\s+(\w+)\s*:\s*(texture_\w+)(?:<(\w+)>)?;\s*$/;

src/scene/shader-lib/chunks-wgsl/lit/frag/clusteredLight.js:306

• Ensure that switching to the 'uniform.shadowAtlasParams' access for shadow texture parameters is compatible with all shader modules that rely on these values.

let shadowTextureResolution: f32 = uniform.shadowAtlasParams.x;