import ModelViewerElementBase from '../model-viewer-base.js';
import { Constructor } from '../utilities.js';
export declare const BASE_OPACITY = 0.5;
export declare const $currentEnvironmentMap: unique symbol;
export declare const $currentBackground: unique symbol;
export declare const $updateEnvironment: unique symbol;
export declare interface EnvironmentInterface {
    environmentImage: string | null;
    skyboxImage: string | null;
    shadowIntensity: number;
    shadowSoftness: number;
    exposure: number;
    hasBakedShadow(): boolean;
}
export declare const EnvironmentMixin: <T extends Constructor<ModelViewerElementBase, object>>(ModelViewerElement: T) => {
    new (...args: any[]): EnvironmentInterface;
    prototype: EnvironmentInterface;
} & object & T;