Cascaded shadow map cleanup and fixes - #749
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…bugs The vendored three.js CSM addon carried a full shader-injection path (setupMaterial / CSMShader / global ShaderChunk patching) that was never activated: no material ever called setupMaterial, so every material compiled the non-CSM fallback branch. What actually renders is N overlapping shadow-casting directional lights at intensity/N. This commit makes that design explicit and deletes the dead half: - Delete CSMShader.js and the ShaderChunk save/restore bookkeeping. The injected chunk was a stale r174-era fork of lights_fragment_begin; the fallback branch every material used is identical to stock three r183, so removal also silently restores current-three behavior for iridescence and point-light shadow guards. - Delete CSMShadowNode.js (WebGPU-only, unreachable in a WebGL app). - Strip setupMaterial, uniform plumbing, fade, and the shaders map from CSM.js; document the layered-lights design at the top of the file. Bug fixes along the way: - Call updateFrustums() when the camera projection matrix changes. Cascade splits and shadow bounds were previously computed once at construction, so window resizes and fov/near/far updates desynced the shadow cameras from the view frustum. - Use ?? instead of || for numeric CSM defaults: a shadow-casting light with intensity=0 was previously kicked back up to the default intensity of 3. - Guard the degenerate zero light direction when a directional light sits exactly at the world origin (the add_light_directional position default); fall back to pointing straight down. - Apply light color reliably on mount: the old color effect ran before the CSM instance existed and its deps never re-fired, so a non-default initial color was silently dropped. - Simplify the wrapper: construct CSM directly in an effect (the CSMProxy indirection existed for the ShaderChunk bookkeeping), reuse CSMHelper.dispose() for debug-helper teardown, and drop the updateMaterialsInScene traversals (three re-selects shader programs itself when the light set changes; the manual needsUpdate sweep was only needed when ShaderChunk globals were being swapped).
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What viser renders is not cascaded shadow mapping in the standard sense: there is no per-fragment cascade selection. Each cascade is an ordinary shadow-casting directional light whose shadow camera is fitted to a view frustum slice, and cascades composite by summing lights, which leaves distant shadows lighter than true CSM would. Rename the code so it stops claiming otherwise: - CsmDirectionalLight -> CascadedDirectionalLight - csm/CSM.js (class CSM) -> shadows/ShadowCascades.js (ShadowCascades) - csm/CSMFrustum.js -> shadows/CascadeFrustum.js - csm/CSMHelper.js -> shadows/CascadeHelper.js The ShadowCascades header documents the approximation and its tradeoff explicitly. The files are also removed from the eslint/prettier ignore lists: those exemptions existed to keep the vendored copy diffable against upstream three.js, which no longer applies now that the code has permanently diverged. No behavior change; the built client renders pixel-identical.
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Remove the unused CSM shader injection machinery, fix cascade desync on window resize plus a few lifecycle footguns, and rename the CSM classes to reflect what is actually implemented (per-cascade shadow cameras composited as overlapping directional lights, not true cascaded shadow mapping).
This PR should have no visual impact.