/**
 * Class representing a 2D vector or point.
 * Implements a fluent, mutating API to reduce object allocations.
 */
export default class Vector2 {
    private _x;
    private _y;
    /** Optional callback fired when x or y is modified. */
    onChange?: () => void;
    /** X coordinate. */
    get x(): number;
    set x(val: number);
    /** Y coordinate. */
    get y(): number;
    set y(val: number);
    /**
     * initialises a new instance of Vector2.
     * @param x Initial x coordinate.
     * @param y Initial y coordinate.
     */
    constructor(x?: number, y?: number);
    /**
     * Sets the components of this vector.
     * @param x New x coordinate.
     * @param y New y coordinate.
     * @returns This vector for chaining.
     */
    set(x: number, y: number): this;
    /**
     * Copies the components of another vector into this one.
     * @param other The vector to copy from.
     * @returns This vector for chaining.
     */
    copy(other: Vector2): this;
    /**
     * Calculates the Euclidean distance between two vectors.
     * @param v1 First vector.
     * @param v2 Second vector.
     * @returns The distance between v1 and v2.
     */
    static distance(v1: Vector2, v2: Vector2): number;
    /**
     * Calculates the dot product of two vectors.
     * @param v1 First vector.
     * @param v2 Second vector.
     * @returns The dot product of v1 and v2.
     */
    static dot(v1: Vector2, v2: Vector2): number;
    /**
     * The length (magnitude) of the vector.
     */
    get magnitude(): number;
    /**
     * A new normalized (unit length) version of this vector.
     * Does not mutate the original vector.
     */
    get normalized(): Vector2;
    /**
     * Normalizes this vector in place.
     * @returns This vector for chaining.
     */
    normalize(): this;
    /**
     * Adds another vector to this one (mutates).
     * @param other The vector to add.
     * @returns This vector for chaining.
     */
    add(other: Vector2): this;
    /**
     * Subtracts another vector from this one (mutates).
     * @param other The vector to subtract.
     * @returns This vector for chaining.
     */
    subtract(other: Vector2): this;
    /**
     * Multiplies this vector by a scalar (mutates).
     * @param scalar The value to multiply by.
     * @returns This vector for chaining.
     */
    multiply(scalar: number): this;
    /**
     * Creates a new vector with the same x and y values as this one.
     * @returns A new Vector2 instance.
     */
    clone(): Vector2;
}