This is a VERY SPECIAL GDL trick.
It is also very simple. So simple that if you are a GDL expert, you will laugh in amazement, but if you are a GDL newbie, you will permanently have a puzzled expression on your face.
So watch out.
This trick is also a trick made special for the book, so even though I am a really helpful guy on Archicad TALK, I don't want to give this one away. So I want you to feel obliged to buy my book if you read further. Of course, in buying the book, you are doing yourself a favor, so please feel free to read on so that you, too, can feel the relief from the guilt of stealing my intellectual property by buying the book, if guilt relief is your thing.
It is true that the GDL parameters can't be reduced enough to work in the neon light trick. If you already have the book, you'll see the script tweak on page 141.
Here's the trick, to reduce the output intensity, for you only if you buy the rest of the book:
General Light>3D Script
now reads:
light g/100*d, g/100*e, g/100*f, !!RGB
change to:
light g/1000*d, g/1000*e, g/1000*f, !!RGB
Please also note that this wll permit low emission light settings to emit colored light and not only white as the situation is now.
Dwight Atkinson