/**
 * Generic sag/catenary curve → point string, ready to loft into a tube. Genre-agnostic — power lines,
 * suspension-bridge cables, ziplines, ropes, hanging chains, festoon lights all hang the same way.
 * `sagCurve` is a cheap quadratic-Bézier droop; `catenaryCurve` is the true cosh hyperbolic cable.
 *
 * @capability catenary sagging cable curve between two anchors
 */
export type { Vec3 } from "./geometry.js";
import type { Vec3 } from "./geometry.js";
/**
 * Quadratic-Bézier sag between two anchors: the control point is pulled straight down so the mid-span
 * lowest point droops by exactly `sag` meters below the chord. Cheap and stable; the go-to for cables
 * where exact catenary physics don't matter. Returns `segments + 1` points.
 */
export declare function sagCurve(a: Vec3, b: Vec3, sag: number, segments: number): Vec3[];
/**
 * True hyperbolic catenary between two anchors — the shape a uniform cable actually takes under
 * gravity. `slack` is the extra length beyond the straight-line distance, as a fraction (0.1 = 10%
 * longer than taut); larger slack droops deeper. Falls back to {@link sagCurve} for a near-taut cable.
 * Returns `segments + 1` points. Anchors may differ in height; the curve interpolates the chord.
 */
export declare function catenaryCurve(a: Vec3, b: Vec3, slack: number, segments: number): Vec3[];