export interface ThreeDriverOptions {
    /** Advance the simulation by `dt` seconds. Typically `scheduler.update`. */
    readonly update: (dt: number) => void;
    /** Draw the current state. Called once per frame after the sim step(s). */
    readonly render: () => void;
    /**
     * Fixed simulation step in seconds (e.g. 1/60). When set, the driver runs whole `update(fixedTimestep)`
     * steps to consume accumulated real time (deterministic step count). When omitted, the driver is
     * variable-step (one `update(realDelta)` per frame).
     */
    readonly fixedTimestep?: number;
    /** Max fixed steps per frame before the backlog is discarded (anti spiral-of-death). Default 8. */
    readonly maxSubSteps?: number;
    /**
     * The requestAnimationFrame to schedule on. Defaults to the global `requestAnimationFrame` when it
     * exists (browser). Pass one explicitly to drive a custom loop; leave undefined in Node and call
     * `tick(dt)` manually.
     */
    readonly requestAnimationFrame?: (cb: (timeMs: number) => void) => number;
    /** The cancelAnimationFrame paired with the rAF above. */
    readonly cancelAnimationFrame?: (id: number) => void;
}
export interface ThreeDriver {
    /** Begin the rAF loop. No-op if already running or no rAF is available (Node — use `tick`). */
    start(): void;
    /** Stop the rAF loop. */
    stop(): void;
    /** True while the rAF loop is running. */
    readonly running: boolean;
    /**
     * Advance one frame by `dt` real seconds and render. The manual entry point for Node/tests (and the
     * loop body the rAF callback calls). Honours `fixedTimestep` (accumulates) when configured. Returns
     * the number of `update` calls made this frame.
     */
    tick(dt: number): number;
}
export declare function createThreeDriver(opts: ThreeDriverOptions): ThreeDriver;
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