import { VecN } from '@holotope/core';
import { type SimplexConstitutiveEvaluationN } from './simplex-constitutive.js';
import { type SimplexConstitutiveHessianVectorEvaluationN } from './simplex-constitutive-curvature.js';
/** Compactly supported lower-measure barrier in intrinsic simplex coordinates. */
export interface SimplexMeasureBarrierMaterialN {
    /** Hard lower chart boundary `m`; evaluation requires `J > m`. */
    readonly minimumMeasureRatio: number;
    /** Barrier activation ratio `a`, with `m < a <= 1`. */
    readonly activationMeasureRatio: number;
    /** Positive energy-density scale `kappa`. */
    readonly stiffness: number;
}
export interface SimplexMeasureBarrierEvaluationN extends SimplexConstitutiveEvaluationN<SimplexMeasureBarrierMaterialN> {
    /** Whether `minimumMeasureRatio < J < activationMeasureRatio`. */
    readonly active: boolean;
    /** Positive intrinsic or orientation-preserving signed current/rest ratio. */
    readonly measureRatio: number;
    /** `(J - minimum) / (activation - minimum)`; may exceed one when inactive. */
    readonly normalizedGap: number;
    /** `d energyDensity / dJ`. */
    readonly energyDerivativeByMeasureRatio: number;
    /** `d^2 energyDensity / dJ^2`. */
    readonly energySecondDerivativeByMeasureRatio: number;
}
export declare const SIMPLEX_MEASURE_BARRIER_LAW_ID = "simplex-measure-barrier";
/**
 * Evaluates a C2-clamped logarithmic lower-measure barrier on a k-simplex.
 *
 * The energy is a proactive force, not an inversion guarantee. Pair it with
 * accepted-state and continuous-chord guards when the lower boundary is a
 * simulation invariant.
 */
export declare function evaluateSimplexMeasureBarrierN(restPositions: readonly VecN[], currentPositions: readonly VecN[], material: SimplexMeasureBarrierMaterialN): SimplexMeasureBarrierEvaluationN;
/**
 * Evaluates the exact matrix-free lower-measure-barrier Hessian direction.
 *
 * Outside the compact activation interval the potential, gradient, and
 * curvature products are all exactly zero.
 *
 * The compact support carries into the curvature for the same reason it
 * holds for the energy: an element comfortably above the activation ratio is
 * not merely cheap to evaluate, it contributes nothing at all, so an
 * inactive element cannot bias a direction it should have no opinion about.
 *
 * @example
 * Flattening a unit tetrahedron towards its base drives the measure ratio
 * `J` down. Above the activation ratio the barrier is silent in energy and
 * in curvature alike; below it, both rise steeply towards the hard chart
 * boundary at `minimumMeasureRatio`:
 * ```ts
 * const rest = [
 *   new VecN([0, 0, 0]), new VecN([1, 0, 0]),
 *   new VecN([0, 1, 0]), new VecN([0, 0, 1])
 * ];
 * const material = {
 *   minimumMeasureRatio: 0.1, activationMeasureRatio: 0.6, stiffness: 1
 * };
 * const directions = [
 *   new VecN([0, 0, 0]), new VecN([0, 0, 0]),
 *   new VecN([0, 0, 0]), new VecN([0, 0, -1])
 * ];
 * const flattenedTo = [0.8, 0.3].map((height) => [
 *   new VecN([0, 0, 0]), new VecN([1, 0, 0]),
 *   new VecN([0, 1, 0]), new VecN([0, 0, height])
 * ]);
 *
 * const curvatures = flattenedTo.map((current) =>
 *   evaluateSimplexMeasureBarrierHessianVectorN(rest, current, directions, material)
 * );
 *
 * // J = 0.8, above activation: exactly zero, not merely small.
 * // J = 0.3, inside the support: the element resists being flattened.
 * curvatures.map((c) => c.products.every((p) => p.lengthSq() === 0)); // [true, false]
 * curvatures.map((c) => c.netProductResidual); // [0, 0] — translation invariant either way
 * ```
 */
export declare function evaluateSimplexMeasureBarrierHessianVectorN(restPositions: readonly VecN[], currentPositions: readonly VecN[], directions: readonly VecN[], material: SimplexMeasureBarrierMaterialN): SimplexConstitutiveHessianVectorEvaluationN<SimplexMeasureBarrierEvaluationN>;
//# sourceMappingURL=simplex-measure-barrier-material.d.ts.map