/** How long the cross-fade takes, in milliseconds. */
export declare const LIGHT_FADE_MS = 300;
/** Where the fade is: `mix` is 0 for the true light and 1 for `lit`. */
export interface LightFade {
    mix: number;
    target: number;
    from: number;
    started: number;
    /** Whether the last step left it still moving, so another draw is wanted. */
    fading: boolean;
}
export declare const newLightFade: (lit?: boolean) => LightFade;
/**
 * Step the fade to `now`. `lit` is where it is going. A change of `lit` starts a fade from where the mix is now (a fade turned round half way goes back from there); with `reduced` it jumps. Returns the same object, updated.
 *
 * @param fade - The fade to step.
 * @param lit - Whether the light is `lit` now.
 * @param now - The clock, in milliseconds.
 * @param reduced - Whether the reader asked for less motion.
 * @returns The fade: `mix` for this frame and `fading` true while another frame is wanted.
 */
export declare function stepLightFade(fade: LightFade, lit: boolean, now: number, reduced: boolean): LightFade;