import { JSONMeta } from "../core/Object3D.js";
import { SphericalHarmonics3 } from "../math/SphericalHarmonics3.js";
import { Light, LightJSON } from "./Light.js";

export interface LightProbeJSON extends LightJSON {
    sh: number[];
}

/**
 * Light probes are an alternative way of adding light to a 3D scene. Unlike
 * classical light sources (e.g. directional, point or spot lights), light
 * probes do not emit light. Instead they store information about light
 * passing through 3D space. During rendering, the light that hits a 3D
 * object is approximated by using the data from the light probe.
 *
 * Light probes are usually created from (radiance) environment maps. The
 * class {@link LightProbeGenerator} can be used to create light probes from
 * cube textures or render targets. However, light estimation data could also
 * be provided in other forms e.g. by WebXR. This enables the rendering of
 * augmented reality content that reacts to real world lighting.
 *
 * The current probe implementation in three.js supports so-called diffuse
 * light probes. This type of light probe is functionally equivalent to an
 * irradiance environment map.
 */
export class LightProbe extends Light {
    /**
     * Constructs a new light probe.
     *
     * @param {SphericalHarmonics3} sh - The spherical harmonics which represents encoded lighting information.
     * @param {number} [intensity=1] - The light's strength/intensity.
     */
    constructor(sh?: SphericalHarmonics3, intensity?: number);
    /**
     * This flag can be used for type testing.
     *
     * @default true
     */
    readonly isLightProbe: boolean;
    /**
     * A light probe uses spherical harmonics to encode lighting information.
     */
    sh: SphericalHarmonics3;
    copy(source: LightProbe): this;
    toJSON(meta?: JSONMeta): LightProbeJSON;
}