//#region src/lights/categoryHash.d.ts
/**
 * Map a user-facing category string to a 2-bit bucket index (0..3)
 * used by `ForwardPlusLighting` to quota-separate fill lights.
 *
 * Design:
 *
 * - **Zero-cost per-frame**: hashed once at `Light2D.category` set-
 *   time, cached on the instance. The per-frame tile-assignment loop
 *   only reads the cached integer.
 * - **Cross-light cache**: identical category strings share a single
 *   hash computation globally. Relying on V8's native string hashing
 *   for the `Map` lookup, we skip djb2 entirely on repeat strings —
 *   a 1000-slime scene computes djb2 once for `"slime"`, 999 map hits
 *   after.
 * - **djb2** chosen for simplicity and stability. ~20ns per 5-char
 *   string on modern engines; well below any measurable budget.
 * - **2-bit output**: we have 4 meta channels per tile (`.x/.y/.z/.w`),
 *   so at most 4 categories can have independent compensation. 5th+
 *   category strings collide into earlier buckets — semantically
 *   "those two categories share a quota", which degrades gracefully
 *   (no crash, just lower separation fidelity).
 * - **Default bucket 0**: lights with no category (the common case)
 *   all share bucket 0. Matches the pre-category single-bucket
 *   behavior exactly.
 */
/**
 * Compute the bucket index (0..3) for a given category string. Returns
 * `0` for `undefined`, `null`, or empty strings — matches the "no
 * category set" default.
 */
declare function categoryToBucket(s: string | undefined | null): number;
/** @internal — test-only helper to reset the cache between test runs. */
declare function _resetCategoryBucketCache(): void;
//#endregion
export { _resetCategoryBucketCache, categoryToBucket };
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