I haven't found any documentation and not much help with the smoke_mask and fire_mask. I did see that they might be broken in some versions of 12.5? But I'm finding that the smoke_mask is mostly white and fire_mask doesn't show much even though I have areas of very hot/bright fire.
I do have the smoke density cranked up so I get very dense smoke but I have also modified the shader to take the density and multiply it by the inverse ramp of heat so that it doesn't cover the fire.
But I'm finding that the more I multiply down the density in these areas which reveals more fire in the beauty pass, the smoke_mask get's whiter instead of blacker.
Anyone know how this vex code works that controls the smoke_mask? Or maybe I'm just missing some settings on the image plane of the mantra node?