WebGPURenderer: Optimize VSM shadow code #32209
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Port optimizations from PR #32181 to the WebGPU renderer: - Extract mean variable for clarity - Add early return optimization for fully lit pixels - Improve variable naming (d, p_max) - Correct variance epsilon from 0 to 0.0000001 - Pre-compute constant (0.65 instead of 0.95 - 0.3) - Remove redundant outer clamp - Add clarifying comments These changes improve performance by reducing operations per pixel while maintaining identical visual output.
📦 Bundle sizeFull ESM build, minified and gzipped.
🌳 Bundle size after tree-shakingMinimal build including a renderer, camera, empty scene, and dependencies.
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Mugen87
reviewed
Nov 7, 2025
| let softnessProbability = variance.div( variance.add( distance.mul( distance ) ) ); // Chebeyshevs inequality | ||
| softnessProbability = clamp( sub( softnessProbability, 0.3 ).div( 0.95 - 0.3 ) ); | ||
| occlusion.assign( clamp( max( hardShadow, softnessProbability ) ) ); | ||
| return float( 1.0 ); |
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This line triggers a new warning in the VSM demo webgpu_shadowmap_vsm:
THREE.TSL: Return statement used in an inline 'Fn()'. Define a layout struct to allow return values.
/cc @sunag
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Related issue: #32181
Description
This PR applies the same optimizations made to the WebGL VSM shadow code to the WebGPU renderer's
VSMShadowFilter:meanvariable to avoid repeateddistribution.xreferenceshardShadow == 1.0(fully lit pixels), skipping unnecessary VSM calculationsdistance→dandsoftnessProbability→p_maxfor consistency0to0.0000001to prevent division by zero.div(0.95 - 0.3)to.div(0.65)clamp()call as values are already in valid rangeBenefits
Visual output remains identical.