rest_ratio & rest2_ratio crazy black magic

[meeotch]

So I've been trying to retrofit the old billowysmoke shader to respect the rest & rest2 fields in order to render a white, puffy cloud of expanding smoke with noise. I inserted a blend into the restpos VOP, as suggested in a couple of older threads on here, but noticed there was still some weird jumping in the texture. Then I noticed the rest_ratio and rest2_ratio detail attributes, and thought, "Oh, even better - I don't have to debug my VOPs."

Except the rest_ratio and rest2_ratio attributes don't seem to follow a simple back-and-forth interpolation between the two fields. They're never exactly 0,1 during the sim - and they don't change every frame:

1018 1	 0
1019 0.24 0.76
1040 0.04 0.96
1051 0.1556 0.8444
1056 0.5196 0.4804
1065 0.8836 0.1164
1975 0.7528 0.2472

[/CODE]

That could be roughly 25 frames peak to trough, but the values are *static* in between the given frames. Also, diving into the stock pyro shader, I don't see a simple blending between two rest positions. There are a bunch of nodes with weird types like "pyroNoiseSpace" that have no documentation.

Has something changed recently to make the rest space interpolation into a black box?