[obiot]

Summary

On the Canvas renderer, "Light2d normal-map lighting requires a GPU backend…" fired as soon as any Light2d existed (since 20.3.0). That was a false alarm for most games.

A light only reaches a sprite with a normal map: WebGL and WebGPU switch to the lit pipeline only when there are active lights and the sprite being drawn has a normalMap. A sprite without one is drawn unlit on every renderer. So a lit game without normal maps loses nothing on Canvas, yet it was warned.

The fix

• The base setLightUniforms (which only Canvas uses) now just counts the lights it's given, as activeLightCount, like the GPU renderers do.
• CanvasRenderer.drawImage warns once when it draws a sprite with a normal map while lights are active.
• The message is unchanged.

Also: setLightUniforms' doc comment had been orphaned, sitting above setFog's doc since setFog was inserted. It's back on its method, and updated (it still said "WebGPU once it lands").

Testing

• Unit tests (tests/lights.spec.js), which replace the old pair that pinned the false alarm:
  • lights alone stay quiet;
  • a normal-mapped sprite under lights warns exactly once;
  • a normal-mapped sprite with no light stays quiet;
  • lights are counted from an array or any iterable.
• Whole-frame tests: a lit world without normal maps stays quiet, with a check that the sprite was really drawn; a normal-mapped sprite under a Light2d warns.
• Mutation testing: 6 deliberately broken versions were caught. A seventh survived because the Set.size shortcut it removed was redundant, so the shortcut was dropped.
• In the browser on Canvas: the Isometric Dungeon and Lights examples (no normal maps) are now quiet; Normal Map and Sprite Illuminator still warn once.
• Full suite and lint: the full suite passes, apart from one real-time timer test that flaked under load; it passes 3 out of 3 on its own and is unrelated. pnpm lint passes.

🤖 Generated with Claude Code

https://claude.ai/code/session_01SeWCkETjW35ZbXDRswV1hx

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has insufficient remaining quota.