import type { TSLMat3Node, TSLUniformNode } from '../../types/tsl.cjs';
import type { MPMMaterialModel, MPMMaterialParticleContext, MPMMaterialStressContext, MPMMaterialUpdateContext, MPMParticleFieldMap } from './MPMFluidModel.cjs';
/** Parameters for the Coulomb-capped granular material. */
export interface MPMGranularModelOptions {
    /** Tait pressure stiffness. */
    stiffness?: number | undefined;
    /** Target particle density. */
    restDensity?: number | undefined;
    /** Coulomb friction coefficient. */
    friction?: number | undefined;
    /** Viscosity below the Coulomb yield cap. */
    flowViscosity?: number | undefined;
    /** Fraction of symmetric APIC shear removed after each transfer. */
    shearDamping?: number | undefined;
}
/** Mutable TSL uniforms owned by {@link MPMGranularModel}. */
export interface MPMGranularUniforms {
    /** Pressure stiffness uniform. */
    stiffness: TSLUniformNode<'float', number>;
    /** Rest-density uniform. */
    restDensity: TSLUniformNode<'float', number>;
    /** Coulomb friction uniform. */
    friction: TSLUniformNode<'float', number>;
    /** Pre-yield viscosity uniform. */
    flowViscosity: TSLUniformNode<'float', number>;
    /** Symmetric APIC damping uniform. */
    shearDamping: TSLUniformNode<'float', number>;
}
/**
 * Drucker-Prager-lite granular material with no extra particle fields.
 * Pressure supplies the Coulomb yield cap; RPIC damping removes residual shear
 * while retaining the antisymmetric APIC spin used by render pose passes.
 */
export declare class MPMGranularModel implements MPMMaterialModel<MPMGranularUniforms> {
    name: 'granular';
    particleFields: MPMParticleFieldMap;
    uniforms: MPMGranularUniforms;
    /** Create a granular material with mutable pressure, friction, and damping controls. */
    constructor({ stiffness, restDensity, friction, flowViscosity, shearDamping, }?: MPMGranularModelOptions);
    initParticle({ particle }: MPMMaterialParticleContext): void;
    stress({ C, density }: MPMMaterialStressContext): TSLMat3Node;
    updateDeformation({ particle, C }: MPMMaterialUpdateContext): void;
}