Now there is one last thing I want to show. This distribution of the rust pattern is wrong. It is completely the same everywhere. The number of rust patches and their size should not be the same everywhere. In almost every real object, the rust starts at the edges and grows inward. The inner regions resist the rust the longest. By the time rust shows in the interior, the edges have very mature rust patches.

So to deal with this we're going to want a rust intensity map (RIM). If you're making an object with traditional UV islands in one large UV map, then you're going to need to draw your RIM by hand.

For my case, I made these props with UV mapping 0 to 1 and straight, rectangular edges. So I can use nodes to construct my RIM.

---

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)