/**
 * Calculate foot of perpendicular from point to line
 *
 * @param p1 - Line start point {x: number, y: number}
 * @param p2 - Line end point coordinates
 * @param p0 - Target point coordinates
 *
 * @returns Foot coordinates on the line
 *
 * @example
 * ```typescript
 * // Vertical line example
 * const foot = calcPerpendicularIntersection(
 *   {x:0,y:10}, {x:20,y:10}, {x:5,y:15}
 * ); // {x:5, y:10}
 * ```
 *
 * @remarks
 * - Input points must define a valid line
 * - Works for infinite lines (not limited to segments)
 */
export declare const calcPerpendicularIntersection: (p1: Coord, p2: Coord, p0: Coord) => Coord;