A shading method and computer graphics system are provided in which a path of light is reflected at a given object from a virtual light source. Firstly, a usage of a first input first output buffer in an electronic device is detected. The second Raman medium receives the intermediate signal beam, a second pump beam, and a second reference beam to responsively generate an output signal beam comprising a Raman sideband of the second Raman medium. A first electrode of the system is immersed in the plating solution while the second electrode is in contact with another than the first surface of the substrate.