/*!
 * Copyright (c) Microsoft Corporation.
 * Licensed under the MIT License.
 */
import { ShaderBase } from "./shader.js";
export declare class Downsample extends ShaderBase {
    private _texture2D;
    private _positionAttribute;
    private _viewportUniform;
    private _samplerUniform;
    left: number;
    top: number;
    width: number;
    height: number;
    focusDepth: number;
    nearFocusDepth: number;
    farFocusDepth: number;
    maxBackgroundBlur: number;
    get texture2D(): WebGLTexture;
    set texture2D(value: WebGLTexture);
    initializeContext(gl: WebGL2RenderingContext): void;
    private _initializeShader;
    apply(): void;
    updateBuffers(): void;
    updateTextures(): void;
}