import type { BufferAttribute } from 'three/webgpu';
export type FluidDiagnosticsOptions = Record<string, unknown>;
export interface FluidMetricSummary {
    mean: number;
    minimum: number;
    maximum: number;
}
export interface FluidMetrics {
    density: {
        meanRatio: number;
        rmsError: number;
        maximumRatio: number;
        maximumPositiveError: number;
    };
    neighbors: FluidMetricSummary;
    velocity: {
        maximum: number;
        mean: number;
    };
    boundaries: {
        projectedParticles: null;
        maximumPenetration: null;
        overlapPairs: number;
    };
    solver: {
        type: string;
        pressureAcceleration?: FluidMetricSummary | undefined;
        viscosityAcceleration?: FluidMetricSummary | undefined;
    };
}
export interface FluidMetricBuffer {
    value: BufferAttribute;
}
export interface FluidMetricsSource {
    particleCount: number;
    solver: string;
    particleRadius?: number | undefined;
    buffers: {
        positions: FluidMetricBuffer;
        velocities: FluidMetricBuffer;
        densities: FluidMetricBuffer;
    };
    solverBuffers?: {
        pressureAcceleration?: FluidMetricBuffer | null | undefined;
        viscosityAcceleration?: FluidMetricBuffer | null | undefined;
    } | undefined;
    ubos?: {
        restDensity?: {
            value: number;
        } | undefined;
        h?: {
            value: number;
        } | undefined;
    } | undefined;
}
export interface FluidMetricsRenderer {
    readonly backend?: unknown;
    getArrayBufferAsync(attribute: BufferAttribute): Promise<ArrayBuffer>;
}
/** Explicit, opt-in metrics state for particle-fluid simulations. */
export declare class FluidDiagnostics<TMetrics = FluidMetrics> {
    options: FluidDiagnosticsOptions;
    pending: boolean;
    lastMetrics: TMetrics | null;
    constructor(options?: FluidDiagnosticsOptions | null);
    requestReadback(): void;
    consumeRequest(): boolean;
    setLastMetrics(metrics: TMetrics): void;
}
/** Explicitly read and summarize particle-fluid GPU state. */
export declare function readFluidMetrics(renderer: FluidMetricsRenderer, fluid: FluidMetricsSource): Promise<FluidMetrics>;