<!-- SOLUV · part 38 -->


		this.x = Math.round( this.x );
		this.y = Math.round( this.y );
		this.z = Math.round( this.z );

		return this;

	}

	/**
	 * The components of this vector are rounded towards zero (up if negative,
	 * down if positive) to an integer value.
	 *
	 * @return {Vector3} A reference to this vector.
	 */
	roundToZero() {

		this.x = Math.trunc( this.x );
		this.y = Math.trunc( this.y );
		this.z = Math.trunc( this.z );

		return this;

	}

	/**
	 * Inverts this vector - i.e. sets x = -x, y = -y and z = -z.
	 *
	 * @return {Vector3} A reference to this vector.
	 */
	negate() {

		this.x = - this.x;
		this.y = - this.y;
		this.z = - this.z;

		return this;

	}

	/**
	 * Calculates the dot product of the given vector with this instance.
	 *
	 * @param {Vector3} v - The vector to compute the dot product with.
	 * @return {number} The result of the dot product.
	 */
	dot( v ) {

		return this.x * v.x + this.y * v.y + this.z * v.z;

	}

	/**
	 * Computes the square of the Euclidean length (straight-line length) from
	 * (0, 0, 0) to (x, y, z). If you are comparing the lengths of vectors, you should
	 * compare the length squared instead as it is slightly more efficient to calculate.
	 *
	 * @return {number} The square length of this vector.
	 */
	lengthSq() {

		return this.x * this.x + this.y * this.y + this.z * this.z;

	}

	/**
	 * Computes the  Euclidean length (straight-line length) from (0, 0, 0) to (x, y, z).
	 *
	 * @return {number} The length of this vector.
	 */
	length() {

		return Math.sqrt( this.x * this.x + this.y * this.y + this.z * this.z );

	}

	/**
	 * Computes the Manhattan length of this vector.
	 *
	 * @return {number} The length of this vector.
	 */
	manhattanLength() {

		return Math.abs( this.x ) + Math.abs( this.y ) + Math.abs( this.z );

	}

	/**
	 * Converts this vector to a unit vector - that is, sets it equal to a vector
	 * with the same direction as this one, but with a vector length of `1`.
	 *
	 * @return {Vector3} A reference to this vector.
	 */
	normalize() {

		return this.divideScalar( this.length() || 1 );

	}

	/**
	 * Sets this vector to a vector with the same direction as this one, but
	 * with the specified length.
	 *
	 * @param {number} length - The new length of this vector.
	 * @return {Vector3} A reference to this vector.
	 */
	setLength( length ) {

		return this.normalize().multiplyScalar( length );

	}

	/**
	 * Linearly interpolates between the given vector and this instance, where
	 * alpha is the percent distance along the line - alpha = 0 will be this
	 * vector, and alpha = 1 will be the given one.
	 *
	 * @param {Vector3} v - The vector to interpolate towards.
	 * @param {number} alpha - The interpolation factor, typically in the closed interval `[0, 1]`.
	 * @return {Vector3} A reference to this vector.
	 */
	lerp( v, alpha ) {

		this.x += ( v.x - this.x ) * alpha;
		this.y += ( v.y - this.y ) * alpha;
		this.z += ( v.z - this.z ) * alpha;

		return this;

	}

	/**
	 * Linearly interpolates between the given vectors, where alpha is the percent
	 * distance along the line - alpha = 0 will be first vector, and alpha = 1 will
	 * be the second one. The result is stored in this instance.
	 *
	 * @param {Vector3} v1 - The first vector.
	 * @param {Vector3} v2 - The second vector.
	 * @param {number} alpha - The interpolation factor, typically in the closed interval `[0, 1]`.
	 * @return {Vector3} 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;
		this.z = v1.z + ( v2.z - v1.z ) * alpha;

		return this;

	}

	/**
	 * Calculates the cross product of the given vector with this instance.
	 *
	 * @param {Vector3} v - The vector to compute the cross product with.
	 * @return {Vector3} The result of the cross product.
	 */
	cross( v ) {

		return this.crossVectors( this, v );

	}

	/**
	 * Calculates the cross product of the given vectors and stores the result
	 * in this instance.
	 *
	 * @param {Vector3} a - The first vector.
	 * @param {Vector3} b - The second vector.
	 * @return {Vector3} A reference to this vector.
	 */
	crossVectors( a, b ) {

		const ax = a.x, ay = a.y, az = a.z;
		const bx = b.x, by = b.y, bz = b.z;

		this.x = ay * bz - az * by;
		this.y = az * bx - ax * bz;
		this.z = ax * by - ay * bx;

		return this;

	}

	/**
	 * Projects this vector onto the given one.
	 *
	 * @param {Vector3} v - The vector to project to.
	 * @return {Vector3} A reference to this vector.
	 */
	projectOnVector( v ) {

		const denominator = v.lengthSq();

		if ( denominator === 0 ) return this.set( 0, 0, 0 );

		const scalar = v.dot( this ) / denominator;

		return this.copy( v ).multiplyScalar( scalar );

	}

	/**
	 * Projects this vector onto a plane by subtracting this
	 * vector projected onto the plane's normal from this vector.
	 *
	 * @param {Vector3} planeNormal - The plane normal.
	 * @return {Vector3} A reference to this vector.