fix(shadows): don't apply hardware depth bias to PCSS shadows#8942
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PCSS shadows store depth in a color buffer and bias in the shader, so the hardware polygon-offset bias is a no-op for PCSS on WebGL2 but is applied inconsistently on WebGPU (the backends use different shadow depth-buffer formats), over-biasing and peter-panning valid self-shadows. Skip the hardware depth bias for PCSS of any light type (PCF still uses it), and refresh it when the shadow type changes.
Build size reportThis PR changes the size of the minified bundles.
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PCSS shadows store depth in a color buffer and apply their bias in the shader, so the hardware polygon-offset depth bias is a no-op for PCSS on WebGL2 but is applied inconsistently on WebGPU (the backends use different shadow depth-buffer formats). On WebGPU this over-biased PCSS shadows, peter-panning valid self-shadows away (e.g. a large terrain casting onto itself).
Changes:
_updateShadowBiasnow skips the hardware depth bias for PCSS shadows of any light type (in addition to the existing non-clustered omni case). The bias is still applied for hardware-compare PCF shadows.Behavior: