import type { Vec2 } from "./geometry.js";
/** A polyline prepared for repeated distance/fraction sampling, with cumulative arc-length precomputed. */
export interface Polyline {
    readonly points: readonly Vec2[];
    readonly cumulative: readonly number[];
    readonly length: number;
}
/** The closest point on a polyline to a query point, with where it lands along the line. */
export interface PolylineHit {
    readonly point: Vec2;
    readonly distanceAlong: number;
    readonly segment: number;
    readonly lateral: number;
}
/** Prepare a polyline from ordered points, computing cumulative arc-length once for O(log n) sampling.
 * @internal
 */
export declare function polyline(points: readonly Vec2[]): Polyline;
/** Point at an absolute arc-length distance along the line, clamped to the endpoints.
 * @internal
 */
export declare function pointAtDistance(line: Polyline, dist: number): Vec2;
/** Point at a `[0, 1]` fraction of the line's total length.
 * @internal
 */
export declare function pointAtFraction(line: Polyline, fraction: number): Vec2;
/** Unit tangent (direction of travel) at an absolute distance along the line.
 * @internal
 */
export declare function tangentAtDistance(line: Polyline, dist: number): Vec2;
/** Closest point on the line to `query`, reporting arc-length position, segment index, and signed lateral offset.
 * @internal
 */
export declare function closestPoint(line: Polyline, query: Vec2): PolylineHit;