import type { Vector3 } from '@holoscript/core';
/**
 * FluidSim.ts
 *
 * SPH fluid: particle-based fluid simulation, viscosity,
 * surface tension, boundary handling, and density queries.
 *
 * @module physics
 */
export interface FluidParticle {
    position: [number, number, number];
    velocity: Vector3;
    density: number;
    pressure: number;
    mass: number;
}
export interface FluidConfig {
    restDensity: number;
    gasConstant: number;
    viscosity: number;
    surfaceTension: number;
    gravity: Vector3;
    smoothingRadius: number;
    timeStep: number;
    boundaryMin: Vector3;
    boundaryMax: Vector3;
    boundaryDamping: number;
}
export declare class FluidSim {
    private particles;
    private config;
    /**
     * FSM-2: Spatial hash for O(N) neighbor queries.
     *
     * Cell size is set to the smoothing radius so that a radius query only
     * needs to inspect a 3×3×3 = 27-cell neighbourhood rather than all N
     * particles.  The hash is rebuilt from scratch each update() call because
     * SPH particles move every step; incremental update would require a remove
     * + re-insert per particle which has the same asymptotic cost on small grids.
     */
    private spatialHash;
    private toArr3;
    constructor(config?: Partial<FluidConfig>);
    addParticle(position: [number, number, number] | {
        x: number;
        y: number;
        z: number;
    }, velocity?: Vector3 | {
        x: number;
        y: number;
        z: number;
    }): void;
    addBlock(min: Vector3 | {
        x: number;
        y: number;
        z: number;
    }, max: Vector3 | {
        x: number;
        y: number;
        z: number;
    }, spacing: number): number;
    private poly6;
    private spikyGrad;
    private viscosityLaplacian;
    update(): void;
    private enforceBoundaries;
    getParticles(): FluidParticle[];
    getParticleCount(): number;
    getAverageDensity(): number;
    getKineticEnergy(): number;
    clear(): void;
    setConfig(config: Partial<FluidConfig>): void;
}
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