Shadow fix: real example validation

Six upstream examples passed. Zero changed pixels and zero browser or GPU errors.

Upstream 1c4264a639, Edge WebGPU, 960 × 600. Each version ran 24 warm-up frames and 120 measured frames with matching random seeds and animation time. Scenes, materials, lights and assets are the original upstream examples.

Both versions were already free of pipeline churn in these examples. These results check compatibility; the mixed-material reproduction demonstrates the fix. Screenshot FPS displays use controlled time and are not performance benchmarks.

Tested fix: aa621821a4 (four added lines). The 14 fixture comparisons per backend are pixel-identical and verify explicit pass IDs, runtime side changes, precompilation and disposal. WebGPU fixture results · WebGL2 fixture results · Test source.

The four-line lookup-table revision was also checked with WebGL2 forced: all six examples render without errors. Five comparisons are exact; the standard shadow-map example varied by one color value in three pixels. A repeated capture of the unchanged patched build also varied by one pixel. WebGL2 report · Repeat controls.

Inspect the WebGL2 color difference · magnified pixels and repeat controls

Full WebGPU measurement report · Example validation source. These are saved captures of the tested stock and patched builds.