hi,
you mean light transmission!?
so call the complete node for example "light transmission node"
viewtopic.php?f=5&t=48999
here the node as "diagramm".(i build a light transmission controller with a bw bitmap. with gamma up and down you can than say more and harder transmitting light with a special light color (extra color controller) or softer and not so much light transmitting. that mean you can control the light power from transmitting light, the color of the transmitting light and the transmitting effect in percent for the "opacity" from the light transmission subnode. only the "opacity effect" is meaned. i call it transmission efficiency. the subnode is de facto the bw bitmap himself and your own free hand gamma correction/interpretation. LOL
snip lwguru