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;

	}
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.