Thanks for the pics.

Here's a (final) attempt based on them. I think given my limited theoretical knowledge about shaders, this is pretty much as good as it gets, unless I stumble across the perfect solution by accident. Lol.

I think to get an absolute exact "translation" of your non-GC shader, you need bagginsbill to "disect" it mathematically and reconstruct it again.

There are just too many variable that influence each other.