I wrote this shader in answer to a question long ago - how do I get a number indicating position along the length of a hair. You might say it's the W coordinate of the UVW (3D) coordinates associated with strand-based hair.

This is a hack - I took advantage of the hair node's root vs. tip color gradation. The color coming out of this node combines that gradient with a lighting equation. By dividing that by "white" hair, the lighting is canceled out and you get simply the position along the gradient.

It is illegal to use lighting nodes as "data" for math in SuperFly, so this isn't a tactic one can use with SuperFly.

However, SuperFly has many other nodes that reveal internal coordinates that FireFly never had. Perhaps there is literally a W coordinate you can get from the strand hair.

Using the "V" coordinate won't cut it - that will color each hair uniformly, not changing from root to tip. It will just change from top to bottom on the UV map.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)