/** Deterministic pseudo-random hash for reproducible particle variation. */
export declare function hash(a: number, b: number): number;
export interface SpawnParams {
    /** Origin x — center of the burst (px). */
    ox: number;
    /** Origin y — center of the burst (px). */
    oy: number;
    /** Scale multiplier applied to speed and size. */
    sc: number;
    /** Number of particles to spawn in this burst. */
    burst: number;
    /** Central emission angle (radians). */
    baseAngle: number;
    /** Angular spread around `baseAngle` (radians). */
    spread: number;
    /** Horizontal position jitter (±half, px). */
    jx: number;
    /** Vertical position jitter (±half, px). */
    jy: number;
    /** Minimum initial speed (px/s, before `sc`). */
    sMin: number;
    /** Maximum initial speed (px/s, before `sc`). */
    sMax: number;
    /** Minimum particle radius (px, before `sc`). */
    szMin: number;
    /** Maximum particle radius (px, before `sc`). */
    szMax: number;
    /** Current timestamp (seconds). */
    now: number;
    /** Ring-buffer rotation index for slot allocation. */
    baseRot: number;
    /** Total number of slots in the ring buffer. */
    slots: number;
    /**
     * Color list index written to every particle in this burst. Use a fixed value
     * (e.g. a series index) to color the whole burst uniformly, or `-1` to cycle
     * the renderer's color list per particle (the particle's loop index is stored).
     * Defaults to `-1`.
     */
    colorIndex?: number;
}
/** Write `p.burst` particles into the ring buffer starting at `p.baseRot`. Returns the next rotation index. */
export declare function spawnBurst(buf: Float64Array, p: SpawnParams): number;
export interface ShakeResult {
    x: number;
    y: number;
    active: boolean;
}
/** Compute screen-shake displacement with exponential decay envelope. */
export declare function computeShake(elapsed: number, dur: number, sc: number, sint: number): ShakeResult;
/**
 * Advance all particles by `dtSec`: apply velocity, drag, and expire particles older than `burstDur`.
 * Returns the number of particles still alive after the tick, so callers can skip per-frame
 * repaint work (bumping `packRevision`) when the field is empty.
 */
export declare function tickParticles(buf: Float64Array, slots: number, now: number, burstDur: number, drag: number, dtSec: number): number;
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