public Vector4f add(Vector4f vec) {
        if (null == vec) {
            logger.warning("Provided vector is null, null returned.");
            return null;
        }
        return new Vector4f(x + vec.x, y + vec.y, z + vec.z, w + vec.w);
    }
<code>add</code> adds a provided vector to this vector creating a
resultant vector which is returned. If the provided vector is null, null
is returned.

@param vec
           the vector to add to this.
@return the resultant vector.
jme3-core/src/main/java/com/jme3/math/Vector4f.java