/**
 * WeatherBlackboard — Singleton shared state for @weather hub trait.
 *
 * The @weather trait owns this blackboard and writes to it each frame.
 * Consumer traits (@volumetric_clouds, @cloth, @fluid, @physics, @erosion,
 * @god_rays, @particle_system) read from it. This creates environmental
 * coherence without trait-to-trait coupling.
 *
 * Pattern: P.GAPS.10 (Hub Trait Architecture)
 *
 * @module environment
 */
export type PrecipitationType = 'none' | 'rain' | 'snow' | 'hail';
export interface WeatherBlackboardState {
    /** Wind direction and magnitude as a 3D vector */
    wind_vector: [number, number, number];
    /** Precipitation intensity 0-1 */
    precipitation: number;
    /** Type of precipitation */
    precipitation_type: PrecipitationType;
    /** Ambient temperature in Celsius */
    temperature: number;
    /** Relative humidity 0-1 */
    humidity: number;
    /** Normalized sun direction vector (from surface toward sun) */
    sun_position: [number, number, number];
    /** Sun light intensity 0-1 (0 at night) */
    sun_intensity: number;
    /** Cloud coverage density 0-1 */
    cloud_density: number;
    /** Cloud layer altitude in meters */
    cloud_altitude: number;
    /** Fog density 0-1 */
    fog_density: number;
    /** Time of day in hours 0-24 (fractional) */
    time_of_day: number;
    /** True when sun_intensity < 0.1 */
    is_night: boolean;
    /** Accumulated surface moisture from rain 0-1 (decays when not raining) */
    surface_wetness: number;
    /** Wind speed (magnitude of wind_vector) */
    wind_speed: number;
    /** Visibility range in meters (affected by fog + precipitation) */
    visibility_range: number;
    /** Frame counter — incremented each @weather update */
    frame: number;
}
/**
 * Global weather blackboard.
 *
 * WRITE: Only the @weather hub trait should write to this.
 * READ: Any consumer trait can read from this each frame.
 *
 * The blackboard is a plain object — reads are zero-cost.
 * The @weather trait must run FIRST in the trait update loop
 * so consumers see the latest state.
 */
export declare const weatherBlackboard: WeatherBlackboardState;
/**
 * Update the blackboard with new values. Recomputes derived fields.
 * Called by WeatherHubTrait.onUpdate() each frame.
 */
export declare function updateWeatherBlackboard(partial: Partial<Omit<WeatherBlackboardState, 'is_night' | 'surface_wetness' | 'wind_speed' | 'visibility_range' | 'frame'>>): void;
/**
 * Reset blackboard to default state. Used in testing.
 */
export declare function resetWeatherBlackboard(): void;
/**
 * Compute sun position from time of day and latitude.
 *
 * Returns normalized direction vector pointing from surface toward sun.
 * At midnight (0/24), sun is directly below horizon.
 * At noon (12), sun is at maximum elevation.
 *
 * @param timeOfDay - Hours 0-24
 * @param latitude - Degrees, default 45 (mid-latitude)
 * @returns [x, y, z] normalized sun direction
 */
export declare function computeSunPosition(timeOfDay: number, latitude?: number): [number, number, number];
/**
 * Compute sun intensity from elevation angle.
 * Smooth ramp: 0 at horizon, 1 at max elevation, with atmospheric scattering falloff.
 */
export declare function computeSunIntensity(sunY: number): number;
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