WinterClaw,

Reading over the thread again, I realized that I may have inadvertantly implied a contradiction to what you said. I meant no disrespect. I was responding to Mark's tentative conclusion that what he asked for was not easy.

I think you mean that getting the streaks to follow a specific curved path is not easy, and that is absolutely true. But Mark didn't ask for that.

In the use case involving this particular hair, the bottom layers are not strictly vertical or horizontal, and procedurally streaking them is a fail.

However, many hairs have two different materials for outer and inner layers, and streaking the outer layers where all the strips are straight is perfectly dealt with here.

Failing that, a trivial mask could be made that removes procedural streaks from the areas where they would contradict what the texture map has in it. Or with some more work, multiple sets of procedural streaks can be combined with masks, so that different angles can be combined into the single UV space. Even diagonal streaks are possible by using U+V and U-V as the driving coordinates. Certain curves that have simple mathematical descriptions are also possible fairly easily. For example, any elliptical path is mathematically straightforward and using matmatic would make the job pretty easy.

A general arbitrary curve would be very tricky, though. Bezier curves or cubic splines are a possibility.

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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)