<!-- NEW2 — TEST 2 · THE DISTRICT OF 800 · part 28 -->
or2} v2 - The second vector.
	 * @param {number} alpha - The interpolation factor, typically in the closed interval `[0, 1]`.
	 * @return {Vector2} A reference to this vector.
	 */
	lerpVectors( v1, v2, alpha ) {

		this.x = v1.x + ( v2.x - v1.x ) * alpha;
		this.y = v1.y + ( v2.y - v1.y ) * alpha;

		return this;

	}

	/**
	 * Returns `true` if this vector is equal with the given one.
	 *
	 * @param {Vector2} v - The vector to test for equality.
	 * @return {boolean} Whether this vector is equal with the given one.
	 */
	equals( v ) {

		return ( ( v.x === this.x ) && ( v.y === this.y ) );

	}

	/**
	 * Sets this vector's x value to be `array[ offset ]` and y
	 * value to be `array[ offset + 1 ]`.
	 *
	 * @param {Array<number>} array - An array holding the vector component values.
	 * @param {number} [offset=0] - The offset into the array.
	 * @return {Vector2} A reference to this vector.
	 */
	fromArray( array, offset = 0 ) {

		this.x = array[ offset ];
		this.y = array[ offset + 1 ];

		return this;

	}

	/**
	 * Writes the components of this vector to the given array. If no array is provided,
	 * the method returns a new instance.
	 *
	 * @param {Array<number>} [array=[]] - The target array holding the vector components.
	 * @param {number} [offset=0] - Index of the first element in the array.
	 * @return {Array<number>} The vector components.
	 */
	toArray( array = [], offset = 0 ) {

		array[ offset ] = this.x;
		array[ offset + 1 ] = this.y;

		return array;

	}

	/**
	 * Sets the components of this vector from the given buffer attribute.
	 *
	 * @param {BufferAttribute} attribute - The buffer attribute holding vector data.
	 * @param {number} index - The index into the attribute.
	 * @return {Vector2} A reference to this vector.
	 */
	fromBufferAttribute( attribute, index ) {

		this.x = attribute.getX( index );
		this.y = attribute.getY( index );

		return this;

	}

	/**
	 * Rotates this vector around the given center by the given angle.
	 *
	 * @param {Vector2} center - The point around which to rotate.
	 * @param {number} angle - The angle to rotate, in radians.
	 * @return {Vector2} A reference to this vector.
	 */
	rotateAround( center, angle ) {

		const c = Math.cos( angle ), s = Math.sin( angle );

		const x = this.x - center.x;
		const y = this.y - center.y;

		this.x = x * c - y * s + center.x;
		this.y = x * s + y * c + center.y;

		return this;

	}

	/**
	 * Sets each component of this vector to a pseudo-random value between `0` and
	 * `1`, excluding `1`.
	 *
	 * @return {Vector2} A reference to this vector.
	 */
	random() {

		this.x = Math.random();
		this.y = Math.random();

		return this;

	}

	*[ Symbol.iterator ]() {

		yield this.x;
		yield this.y;

	}

}

/**
 * Class for representing a Quaternion. Quaternions are used in three.js to represent rotations.
 *
 * Iterating through a vector instance will yield its components `(x, y, z, w)` in
 * the corresponding order.
 *
 * Note that three.js expects Quaternions to be normalized.
 * ```js
 * const quaternion = new THREE.Quaternion();
 * quaternion.setFromAxisAngle( new THREE.Vector3( 0, 1, 0 ), Math.PI / 2 );
 *
 * const vector = new THREE.Vector3( 1, 0, 0 );
 * vector.applyQuaternion( quaternion );
 * ```
 */
class Quaternion {

	/**
	 * Constructs a new quaternion.
	 *
	 * @param {number} [x=0] - The x value of this quaternion.
	 * @param {number} [y=0] - The y value of this quaternion.
	 * @param {number} [z=0] - The z value of this quaternion.
	 * @param {number} [w=1] - The w value of this quaternion.
	 */
	constructor( x = 0, y = 0, z = 0, w = 1 ) {

		/**
		 * This flag can be used for type testing.
		 *
		 * @type {boolean}
		 * @readonly
		 * @default true
		 */
		this.isQuaternion = true;

		this._x = x;
		this._y = y;
		this._z = z;
		this._w = w;

	}

	/**
	 * Interpolates between two quaternions via SLERP. This implementation assumes the
	 * quaternion data are managed in flat arrays.
	 *
	 * @param {Array<number>} dst - The destination array.
	 * @param {number} dstOffset - An offset into the destination array.
	 * @param {Array<number>} src0 - The source array of the first quaternion.
	 * @param {number} srcOffset0 - An offset into the first source array.
	 * @param {Array<number>} src1 -  The source array of the second quaternion.
	 * @param {number} srcOffset1 - An offset into the second source array.
	 * @param {number} t - The interpolation factor. A value in the range `[0,1]` will interpolate. A value outside the range `[0,1]` will extrapolate.
	 * @see {@link Quaternion#slerp}
	 */
	static slerpFlat( dst, dstOffset, src0, srcOffset0, src1, srcOffset1, t ) {

		let x0 = src0[ srcOffset0 + 0 ],
			y0 = src0[ srcOffset0 + 1 ],
			z0 = src0[ srcOffset0 + 2 ],
			w0 = src0[ srcOffset0 + 3 ];

		let x1 = src1[ srcOffset1 + 0 ],
			y1 = src1[ srcOffset1 + 1 ],
			z1 = src1[ srcOffset1 + 2 ],
			w1 = src1[ srcOffset1 + 3 ];

		if ( w0 !== w1 || x0 !== x1 || y