/// <reference types="@webgpu/types" />
import { HasReactive } from "@reactively/decorate";
import { Cache, ComposableShader, ValueOrFn, Vec2 } from "thimbleberry";
import { HistogramModule } from "../binop/HistogramModule.js";
import { ComponentName, LoadComponent } from "../util/GenerateLoadTexel.js";
export interface HistogramTextureParams {
    device: GPUDevice;
    /**
     * Source data to be reduced.
     *
     * A function returning the source buffer will be executed lazily,
     * and reexecuted if the function's `@reactively` source values change.
     */
    source: ValueOrFn<GPUTexture>;
    /** {@inheritDoc HistogramTexture#blockSize} */
    blockSize?: Vec2;
    /** {@inheritDoc HistogramTexture#bufferBlockLength} */
    bufferBlockLength?: number;
    /** {@inheritDoc HistogramTexture#forceWorkgroupSize} */
    forceWorkgroupSize?: Vec2;
    /** {@inheritDoc HistogramTexture#histogramOps} */
    histogramOps: HistogramModule;
    /** {@inheritDoc HistogramTexture#minMaxBuffer} */
    minMaxBuffer?: GPUBuffer;
    /** {@inheritDoc HistogramTexture#bucketSums} */
    bucketSums?: boolean;
    /** {@inheritDoc HistogramTexture#range} */
    range?: Vec2;
    /** {@inheritDoc HistogramTexture#sourceComponent} */
    sourceComponent?: ComponentName | LoadComponent;
    /** cache for GPUComputePipeline */
    pipelineCache?: <T extends object>() => Cache<T>;
    /** {@inheritDoc HistogramTexture#label} */
    label?: string;
}
/**
 * Calculate a histogram from a source texture.
 *
 * Internally, a cascade of shaders is run: the first shader calculates a separate
 * histogram for each part of the screen, and then a series of reduction shaders
 * combine the partial histograms.
 *
 * The number of buckets in the histogram is configurable.
 *
 * The range of values to spread across the buckets is also configurable.
 * The range may be specified by the cpu, or dynamically provided
 * some other shader writing to a two element GPUBuffer.
 *
 * Optionally, the sum for each bucket can also collected in parallel with the
 * frequency counts in the histogram. The sums are reported in a separate buffer.
 */
export declare class HistogramTexture extends HasReactive implements ComposableShader {
    source: GPUTexture;
    /** length of block to read per thread when reading from the source texture */
    blockSize: Vec2;
    /** number of histograms to read per thread when reducing from buffer to buffer */
    bufferBlockLength: number | undefined;
    /** wgsl macros for histogram reduction and histogram size.
     * Typically call `histogramModule()`
     */
    histogramOps: HistogramModule;
    /** select or synthesize a component from the source texture
     * @defaultValue "r"
     */
    sourceComponent: ComponentName | LoadComponent;
    /** range of histogram values (or provide minMaxBuffer)
     * @defaultValue [0, 255]
     */
    range?: Vec2;
    /** buffer containing min and max values for the histogram range (or use range) */
    minMaxBuffer?: GPUBuffer;
    /** Override to set compute workgroup size e.g. for testing.
      @defaultValue maxComputeInvocationsPerWorkgroup of the `GPUDevice` (256)
      */
    forceWorkgroupSize: Vec2 | undefined;
    /** optinally calculate sums for each bucket in addition to counts
     * @defaultValue false
     */
    bucketSums: boolean;
    /** Debug label attached to gpu objects for error reporting */
    label?: string;
    device: GPUDevice;
    private usageContext;
    private pipelineCache?;
    constructor(params: HistogramTextureParams);
    commands(commandEncoder: GPUCommandEncoder): void;
    destroy(): void;
    /** Execute the histogram immediately and copy the results back to the CPU.
     * (results are copied from the {@link HistogramTexture.result} GPUBuffer)
     *
     * To use HistogramTexture in concert with external shaders,
     * instead use {@link HistogramTexture.commands} or `ShaderGroup`.
     *
     * @returns a single histogram in an array
     */
    histogram(): Promise<number[]>;
    /** accumulated histogram (frequency counts) */
    get result(): GPUBuffer;
    /** accumulated bucket counts, only valid if `bucketSums` is true */
    get sumsResult(): GPUBuffer;
    /** create a range buffer if necessary */
    private get rangeBuffer();
    /** create a buffer to hold the range values */
    private get createdRangeBuffer();
    /** all shaders needed to reduce the texture to a single reduced value */
    private get shaders();
    /** shader to reduce the texture to a buffer */
    private get textureToHistograms();
    /** created only if necessary, a shader to reduce the histograms buffer to a single element */
    private get reduceBucketCounts();
    /** created only if necessary, a shader to reduce the histograms buffer to a single element */
    private get reduceSumCounts();
    private get reduceBufferNeeded();
}