@dink: you are the "alpha blending emulation" magician!
... a little O.T. : I remember my "SEGA Saturn" days (about 21-22 years ago), the hardware management of translucencies (alpha blending effects) was very limited... IIRC the Saturn can only manage the alpha channel between the layers... in few words, all sprites/polygons are generated in the same layer, so they can be translucent with other layers (e.g. with the background layer/s), but they can't be translucent among them (in a 3D object this is a big limitation)...